Open thread – a little late because of the holiday. But everyone can get back to work now!
Reader Interactions
591 Responses to "Unforced variations: Sep 2012"
dbostromsays
Effects of “adaptation” are strange and unpredictable. Maple syrup harvests in NE U.S. collapse, rising value of syrup leads to a vast theft of strategic reserves of maple syrup held by friendly neighbors to the north:
“The [Federation of Quebec Maple Syrup Producers] is currently evaluating the scope of the situation. The empty barrels found on site suggest that their contents had been emptied into other containers in view of illegal distribution. In total, the burglarized warehouse held over 10 million pounds of maple syrup amounting to over 30 million dollars in value.
The marketing of the stolen maple syrup will affect the entire maple industry. It is crucial to identify those responsible for this crime.
In addition, several American states saw a very low, indeed catastrophic, harvest during the 2012 season. The Quebec harvest, however, remained normal. The Federation`s maple syrup inventories supply markets during periods of weaker harvests and can, therefore, be considered a global strategic reserve.”
Begin hording; I’m going to do a John Denver and install a storage tank in my yard.
Is there a futures market for this stuff?
JCHsays
Gavin – I do not know that you reduced any confusion among lay people like me. Trenberth said the additional heat being found in the oceans could come back to haunt us. I do not understand what you’ve said, but my hunch is you’re saying as long as the current energy imbalance exists, the system is gaining energy as time goes by. I assume you mean its moving around within the system does not count as a reappearance. If the energy imbalance were to go the other way, then I assume you mean the heat would reappear in terms of its imminent exit to space. If not that, I don’t have a clue what you mean.
[Response: I don’t know what Trenberth is referring to specifically i.e. whether he is speaking metaphorically or literally. But the Ocean Heat content increase is effectively irreversible. The heat being sequestered in the deep ocean is not coming back anytime in the next thousand years or so. – gavin]
dbostromsays
How about the difficulty of heat getting -into- the ocean? How long before our charge card is impolitely declined when we present the tab for our ongoing drunken spree?
Bad metaphor actually; I suppose it’ll be more a matter of raised eyebrows and increasingly watered-down drinks, leading to a shocking hangover.
J Bowerssays
@50 Hank. It was my error. Got my Wa’s mixed up being a Brit and all.
Karsten V. Johansensays
Some days ago a leading newspaper in my country, “Aftenposten” (“The Evening Post”) presented the postulates in this article:
in a very positive tone (but the journalist hadn’t understood any of the arguments in the article, it appeared. At least he wasn’t capable of presenting them to the public without wreaking heavoc to most of elementary atmosphere physics etc.)
I then read this article and understood a whole lot more, but still I must admit, that I’m not very convinced by the theory of mr. Seager.
Firstly I can’t understand what happens to the waves in the jet stream and to the polar front’s movements – they seem to disappear completely?
Secondly, he doesn’t offer any explanation for the causes of the younger dryas cooling, the sudden coolings during the Weichsel ice age etc. etc.
Thirdly he does’t seem to reflect on *what causes the cool airmasses arriving at the north american east coast to warm up again when crossing the Atlantic from southwest towards northeast, if not overwhelmingly the warm surface waters of the Gulf Stream and the north Atlantic Stream*?
Therefore Seager does not understand why the west coasts of Portugal, France, Ireland, Scotland and Norway are clearly warmer than the west coast parts of the north american continent at the same latitudes (f.ex. the alaskan west coast is considerably colder than the norwegian west coast as far as I know). In fact he does not mention or discuss these facts at all.
Some of his (?) figures seems somewhat enigmatic to me. Especially fig.s 5 and 6.
“Geomagnetic oscillations compared to the CET (Central England Temperature) spectrum, which is far more robust and I suggest correct
GMF 85yr, 50yr, 35yr
CET 90yr, 55yr, 35yr”
I’m afraid that such statements do _not_ give me the impression that you agree with radiative forcing of anthropogenic CO2, or in fact any significant human influence on temperature changes.
Patrick 027says
Re Chris Korda @ 32 – in search of a distinction (this doesn’t address the whole of the two issues, one of which is mostly OT I believe and so I won’t add any more than what I previously said, which is…)
Re Hank Roberts @ 14 – I’ve now read the whole thing (sans many comments). Wow! (Part of that reaction due to my having had some similar thoughts** ((where is gar…) capitalism itself should have some *tendency* to put the ‘best/brightest’ in charge; aren’t labor unions a part of free enterprise? (natural law…) Humans are natural – ergo regulated and quasi-free markets are natural (as is love, as is war, …), etc.; (~CEOs/where is gar…) no matter how unregulated a market it, at some point sombody is allocating something; big business becomming sort of government…; etc.) But did I miss something – for whom was his blunt answer (or does it matter)?
**-planted in my mind when I read “Earth” when I was ~12/13-ish? Actually, “Complexity” probably had something to do with it, too… etc.
(One section reminded me of Fareed Zakaria’s “The Future of Freedom”)
Not sure if this is appropriate or not, but since it’s ‘Unforced Variations’…
I’ve just written a draft of a paper that will form a chapter of my economics PhD. It’s an economics of climate change paper and I’ll get plenty of comments from economists in the department. I’d be very interested in also getting comments from climate scientists though, especially on my accuracy in describing the position of climate scientists and the climate science ‘community’.
Re 52 JCH – my impression – though I may not have read enough of the original source – was that if temperature was not rising as rapidly because the ocean was heating up faster than expected for the time being, eventually this could stop and the temperature would rise faster (?) or maybe it was a reference to heat capacity in general (that there is ‘warming in the pipeline’).
Re 40 Andrew W – The water cycle is an important part (the larger part) of convective heat flux from the surface to the atmosphere, although net radiation is generally significant. I’m not sure if it makes sense to isolate one part like that, though. (from memory:) I think tropopause-level forcing for CO2 is greater than surface forcing; thus the atmosphere to some extent would tend to warm first and then a resulting reduction in (the vertical heat flux of) convection would lead to surface warming. However, the water vapor feedback is, I think, supposed to be stronger at the surface than at the tropopause, which would tend to lead to surface warming first, then an increase in convection… The ocean would generally be cooled by rain (which tends to be cooler than the air (unless the cloud touches the surface, there would tend to be some evaporative cooling of the rain; anyway it’s falling from higher-up and temperature tends to decrease with height (with the exception of fronts and the like (gust fronts), nocturnal inversions, etc.)). But except for snowfall, there is no latent heat uptake when the rain hits the surface, whereas there is evaporative cooling when the water goes back up, much larger than the sensible heat associated with a few K difference in temperature.
There is an upper mixed layer of the ocean which comes to equilibrium with climate forcing *relatively* fast due to *limited* heat capacity. Using τ = C/(B-F) = C*ECS , using ECS = 0.75 K*m^2/W and C ~= 200 MJ/(K*m^2), τ ~= 150 Ms ~= 5 years (That’s the e-folding time; you have to multiply it by some factor to get closer to equilibrium). That C is approximately what you’d get from a global 50 m deep layer of water (which would be a bit deeper when compressed into oceanic areas (I’ve seen different numbers given for the depth of the mixed layer – of course it varies regionally and seasonally). You only get roughly 10 MJ/(K*m^2) for sensible heat of the atmosphere; I think (from memory) the latent heat of additional water vapor is of a similar order of magnitude to that. Etc.) Exchange with the deeper ocean limits the rate of additional oceanic heating.
Patrick 027says
Re my last comment:
You only get roughly 10 MJ/(K*m^2)
Since the troposphere and stratosphere are going in opposite directions, you’d want to use tropospheric C (after stratospheric adjustment (to instantaneous forcing – there is some stratospheric response to surface+tropospheric warming too but I think it’s supposed to be small)), which I remember being something like 85 % of the atmosphere (by mass and thus by C).
“It’s not like the Greenland ice sheet is now set to fall completely apart within a decade after one time with nearly all the surface near or above freezing, but it’s going to keep shrinking.” [new paragraph] “At least not for a very long time.” … that last part should have been in () and placed right after ‘within a decade’.
“
Andrew Wsays
I ask because I’ve recently once again come across the claim that CO2 can’t warm the oceans because the downward IR won’t penetrate the ocean mm thick skin layer. Those waving this claim imply that there’s no other mechanism to warm the oceans.
[Response: Nonsense. And easily demonstrated nonsense at that – how do these people explain the increase in ocean heat content? Or even the everyday heat exchange that is ongoing all the time? Evidently there must be mechanisms that transfer heat between the atmosphere and ocean. You can see them in the wake of a hurricane – where wind stirring transfers warm water to depth, and then atmospheric fluxes restore the surface heat content. Those fluxes include solar radiation, latent and sensible heat as well as long wave radiation combined with mechanical stirring from winds and waves. – gavin]
Patrick 027says
Re 55 Karsten V. Johansen – I’m not sure specifically about the size of the role of the Gulf Stream in heating Europe vs Kuroshio heating the Pacific Northwest, but the explanation of atmospheric waves made sense to me.
Specifically, the momentum equations for a fluid on a rotating planet can be analyzed and it can be shown that, absent viscous or diabatic processes (radiant or sensible or latent, or frictional (or for that matter, chemical, electical, or nuclear) net heating or cooling, or mixing, as opposed to adiabatic temperatue changes), and with some simplifying approximations (ignore the small ‘curvature terms’), using potential temperature as a vertical coordinate, there is a quantity called potential vorticity (PV) which is conserved following fluid motion. This is the measure of angular momentum mentioned in the “American Scientist” article – with a clarification – the article seems to be describing a barotropic version, which applies to an unstratified fluid layer.
PV is proportional to absolute vorticity divided by fluid layer thickness (since mass is conserved, the fluid layer thickness is in terms of mass per unit area. If the situation allows an approximation of incompressibility, then volume per unit area (or just depth) can be used instead). Sticking with the vertical component of vorticity, absolute vorticity is equal to planetary vorticity (the vorticity of the rotation of the solid Earth about the local vertical, which is proportional to the sine of the latitude and happens to be equal to the coriolis parameter f (for just horizontal components, coriolis acceleration = f*(cross product of velocity and a unit vector pointing up), and the relative vorticity, which is the vorticity of the wind (or currents) – this actually has two parts: a curvature/orbital vorticity (requires a curvature of streamlines) and shear vorticity (the change in speed across streamlines). In a stratified fluid, the rate of change of pressure relative to potential density (or potential temperature in the atmosphere) can play the role of fluid layer thickness in the proportionality with PV – which may then be called ‘IPV’ or ‘isentropic potential vorticity’.
(PS potential temperature is the temperature that a substance will have if brought adiabatically to a reference pressure. The potential density is the density it would then have. In the above, potential density must be used in the ocean because changes in salinity can affect it independently of potential temperature. Variations in water vapor and liquid water content in clouds can do this in the atmosphere but they tend to have small effects on density for familiar conditions and can for some purposes be ignored.)
PV and IPV are very powerful concepts – it is possible, with boundary conditions and an assumed relationship (like geostrophy or gradient wind balance) to reconstruct a flow pattern from an IPV distribution, and with the assumption that IPV is conserved, the flow pattern determines how IPV is redistributed.
…
David B. Bensonsays
dcomerf @60 — Your paper seems largely sensible to this amateur. However, it is quite clear that a rapid warming of even just 2 degrees Celcius (2 K) will place great stresses on the living environment, so great (I think) as to constitute a catastrophe. One should think in terms of geologic time; from Present (1950 CE) until that 2 K of warming is but an instant of geologic time and in that sense is already a forseeable catastrophic tipping point.
Indeed I think we are more than half way (measured from Present) to a mere 1 K warming and Terra has already experienced economically quite damaging events in various regions; at a 1 K warming it will be rather terrible. So I opine that a 2 K goal is far, far too large to be bourne.
The problem is not that there is heat in the ocean, but rather that there ISN’T heat in the ocean (yet).
(Using the common informal meaning of “heat” as energy or temperature, not the formal thermodynamic definition as energy flow from temperature difference!)
The ocean is accumulating energy at present, and the rate at which energy is being accumulated through heating of the ocean is effectively equal to the difference between what energy Earth absorbs from the Sun, and what energy it emits back to space. The energy imbalance at the Top Of Atmosphere, in other words.
There are two major significant drivers of the energy imbalance at present times. One is the increasing atmospheric greenhouse effect, which means that less energy gets out to space for a given surface temperature. The other is the increasing surface temperature, which increases the energy out into space. These will, eventually, come into approximate balance. Right now, they are not.
It’s technically incorrect to say that there’s some kind of energy in the ocean now which is going to be a problem later. What there is in the ocean is an energy flux (or energy per unit time) that is now going into heating of the ocean. There’s an energy flux down into the ocean which eventually, as the Earth gets back into approximate equilibrium sometime in the future, will be an energy flux back out into space, driven by a higher surface temperature and a warmer ocean.
This is also called “warming in the pipeline”.
Thermodynamic terminology is a pain. (And I’ve done the usual thing here with technical misuse of the term “heat”.) I can see how someone might speak of ocean heat coming back to haunt us. There is a flow of energy into the ocean which is going to result in temperature changes in the future; and we can’t avoid that. It’s already implicit in the CURRENT atmospheric greenhouse. Stopping atmospheric changes right now would still mean that flow of heat into the ocean is going to bring about increasing temperatures in the future.
But it’s really easy to get mixed up in terminology.
(PS it is possible for an adiabatic process to include latent heating/cooling. Due to the kinetics of phase changes (nucleation, diffusion of matter and energy down gradients), etc (activation energy where chemical reactions are involved), some entropy will be produced, but if the approach to thermodynamic equilibrium is sufficiently fast relative to pressure changes, the process can be approximated as isentropic (reversable, and adiabatic). However, in the atmosphere, it is potential temperature defined by dry (no condensation/evaporation etc.) adiabatic processes that tends to either increase with height or stay constant in mixed layers, and the seperation of condensed water from the air in which it condensed generally leads to irreversability (gain in entropy, non-adiabatic), so it is convenient to distinguish between dry adiabatic and moist adiabatic processes), and it is easier to describe IPV using potential temperature defined by dry adiabatic processes as a vertical coordinate.)
…
Anyway, the flow (wind/current velocity field) and (I)PV can be described as sums of components, such as anomalies plus some background/basic/reference state. Within each group (velocity and PV seperately), they add linearly to the total, but (I think**) the relationship between a PV anomaly and the velocity field associated with it can depend on the rest of the components, although linear superposition can be a good approximation for weak anomalies.
The velocity field around a (anti)cyclonic PV anomaly will itself be (anti)cyclonic; if the PV anomaly is of limited extent, the velocity anomaly can extend beyond the PV anomaly. A relatively horizontally large PV anomaly with sharp edges can have a calm central area with a jet-like flow around its boundary. Jets in general are associated with sharper PV gradients.
Because of the distribution of planetary vorticity (which is to a very very good approximation, constant), (I)PV generally tends to become more cyclonic towards the poles. With this gradient direction, if (I)PV contours are brought closer together, eastward (westerly) flows occur; if farther apart, flow may be in the opposite direction (or if relatively farther apart, flow may be westerly but weaker).
With such a north-south PV gradient, North-south displacments of fluid produce PV anomalies, which induce relative vorticity anomalies and associated flow patterns. A wavy displacment field causes a flow field that acts to produce a wavy displacment field that is shifted from the original; the overall effect is that (I)PV anomalies propagate in the presence of a background (I)PV gradient, giving rise to ‘vorticity waves’.
Setting aside the flow pattern, regions of thinner fluid layers tend to have larger (I)PV; this can be from underlying topography, or variations in the top of the fluid layer. In a stratified fluid, one can think of many layers that each thin-out approaching an underlying or overlying boundary – thus, gradients in potential density at a boundary are like IPV gradients and in fact, using the same relationship (geostrophy or gradient-wind balance), surface potential they induce flow patterns like IPV anomalies do (consider the flow pattern associated with the IPV anomaly across the other side of the boundary that would be necessary to induce the potential density anomaly itself).
Any such PV (or surface potential density) gradient can support vorticity waves. Phase propagation is always directed with increasing cyclonic PV to the right (at some angle), but a region of wave activity propagates with group velocity, which depends on the orientation of the waves and the wavelength – in a stratified fluid it can have vertical as well as horizontal components.
Waves can produce velocity fields that extend into regions of opposing (I)PV gradients, where there can be counter-propagating waves. These waves can interact – for a range of wavelengths and other conditions, they will act to maintain a phase relationship that leads to mutual amplification. With surface potential temperature tending to increase equatorward and cyclonic IPV in the atmosphere tending to increase poleward, such counterpropagating waves can occur and grow (via baroclinic instability).
The waves discussed in the article are of the ‘quasi-stationary’ sort. The wavelengths are too long to maintain a phase relationship required for baroclinic instability. A freely propagating quasi-stationary wave has sufficient wavelength to be able to propagate (refering to phase propagation) through the air with a speed similar to the speed the air is moving (and in the opposite direction). If air is flowing over topography, a voricity wave can be forced (it will tilt back into the flow with height so that the group velocity is away from the source (although this tilt may be small within a given vertical extent, such as in the troposphere, I think**); this transports a momentum flux upward, so that the tendency for topography to impeed flow can bypass intermediate layers and act to slow down flow at some higher level where the wave amplitude leads to nonlinear wave breaking (see ‘sudden stratospheric warming’). I think (from memory**) the wave response to flow over topography is supposed to be largest near wavelengths which would freely propagate in the opposite direction at the same speed (resonance). While phase propagation is limited in direction, a global wave pattern can form as wave activity spreads out with group velocities of a spectrum of forced waves; this behavior can also result from wave forcing by diabatic anomalies, such as atmospheric heating over a warm SST anomaly (see also ‘ENSO’).
Baroclinic waves aren’t eliminated from this picture; they occur on top of it (although I think they interact with it too. Extratropical storm track activity produces momentum fluxes as well as heat fluxes, which reshape the PV distribution, etc.)
Oceanic gyres can also be described in terms of PV. I think they might be described as standing vorticity waves.
Of course diabatic and viscous processes occur, but these don’t generally mask such behavior, they just modify it (or in some cases, force it).
Chris Ho-Stuartsays
Hank asks in #67:
>> is now
> since when?
It’s tough to know who you are asking; but since I used the phrase “is now” in the prior comment #66, I’ll take a stab:
I said:
> What there is in the ocean is an energy flux (or energy per unit time) that is now going into heating of the ocean.
The present imbalance and consequent flow of heat into the ocean has most likely been since the mid twentieth century, I think. Sorry if I picked the wrong “is now”.
JCHsays
Chris Ho-Stuart, what you are saying makes no sense to me. If the system is in equilibrium, would not OHC remain roughly the same? What I have been imaging is equilibrium means the heat going into the oceans would equal the heat leaving the oceans.
The way I understand it, that would be the point where the pipeline runs dry. The warming would be over with. The enhanced greenhouse effect would have finished its job of bringing the earth’s system into balance.
When Trenberth made his comment I figured he meant natural variation, in the form of El Nino, would lead to 1998-style boosts in the GMT. My assumption has been that during a El Nino heat leaves the ocean and warms the SAT. I’m starting to doubt this now.
In 1998, if not from the oceans, from where did the additional warmth come?
[Response: There are obviously anomalous fluxes to and from the ocean due to ENSO – though the numbers are small in the aggregate. But ENSO is mainly an upper ocean phenomenon and does not show up much (if at all) in even the 0-700m ocean heat content record (unlike volcanoes, whose effects are clear). – gavin]
owl905says
Paul @28 –
“US commitment would have been a reduction, by 2012, to 93% of 1990 levels.” Extended by Rio to 2017-2020. They’ll probably make it.
“2010 US emissions were 112% or 114% of 1990 levels”
Baseline of early 90s was 1992. The decline for 2010-2012 is pronounced.
“Obviously the proof will be in 2012 annual emissions figures ”
The proof of the ‘make by accident’ will be in 2017. The benny would be making it by 2015, and taking a miraculous leadership revival role.
The criticism of 1st-quarter is unwarranted, since it’s a quarter-over-quarter comparison. However, the trend and flow shows the same thing in the Economist article:
Candide @30. “if the reduction in CO2 emissions isn’t being offset entirely by increased methane emission ”
Methane is the combustion input, not the pollution by-product.
“It is very clear that combustion of natural gas in power plants produces substantially less — about half — the carbon dioxide (CO2) that is produced by a coal fired power plant for the same amount of electricity produced.”
The EPA has already enacted legislation that is aimed at carcinogen agents, but has a ripple effect of reducing methane escape.
It isn’t perfect, but it’s world-wide headlines, and it’s one of the biggest pushback against rising GHG emissions to date.
Apologies to both posters for the delayed response.
J Bowerssays
As wind affects Earth’s rotation thus the length of a day, and storms are expected to strengthen the warmer it gets, wouldn’t this be evidence that climate change really will mess up your days? Okay, by fractions of a millisecond, but…
Ray Ladburysays
Andrew W., Is it your correspondent’s contention that the skin layer is a static boundary layer? Has [edit] he ever been to the ocean? Does he not realize that there are these things called “waves” and “wind” that are continually breaking up the surface layer?
KR (It would be nice to know to whom one is addressing, feels a bit odd communicating to a couple of letters)
You say: I’m afraid that such statements …….
KR, there is noting to be afraid of
My website contains more than 300 graphs (not all listed) of various ‘correlations’ some true some coincidental. Some data show long term temperature changes natural or forced and some none, here are two examples from the longest and the most scrutinized temperature records: http://www.vukcevic.talktalk.net/CET-Jun.htm http://www.vukcevic.talktalk.net/CET-NAP.htm
Now compare two sections from the second graph http://www.vukcevic.talktalk.net/CET1690-1960.htm
coincidence? Maybe, or maybe not.
The graph you quote http://www.vukcevic.talktalk.net/GSC1.htm
It shows de-trended values not anomalies, either data is wrong (from giss, noa, sidc and ethz all world reputable institutions), my email is on the graph so if you request more details, I shall be happy to provide it, for any of the above.
As far as raditive forcing of GHG is concerned multitude of expert opinions is available, my interest is natural i.e.unfoced variations as the thread suggests.
Dr. Schmidt and I went to the same university (albeit different degrees, mine is only an MSc in applied engineering) but that is not reason that we should agree. We look at the same data from different stand point of view and get to different conclusions.
KR, as I said , there is noting to be afraid of about that.
wilisays
Apologies if this has already been posted.
asl.umbc.edu/pub/yurganov/methane/YurganovCCL.pdf
Takeaway line (for me, at least):
“The main conclusion of this paper is a qualitative detection of high and over the years increasing methane mixing ratios in areas coinciding with predicted locations of methane hydrates.”
Sounds like pretty good evidence that methane hydrate release has begun and is accelerating. The main question now is what is the rate of accelerate, and will that rate be further increased by a newly ice-free (or nearly so) Arctic Ocean.
Patrick 027says
Re 63,68 Andrew W –
You’ll find people who don’t get how the climate system’s energy fluxes work in equilibrium, so they will have trouble imagining how disequilibrium works too. Some will say that the 2nd law of thermodynamics forbids heat to flow from cold to hot and thus backradiation can’t exist (untrue in two ways*1*), or that the greenhouse effect amounts to a perpetual motion machine and suggests that you could put something in a microwave and have it heat itself up with no added energy, etc. Perhaps some of the confusion is based on mixing up climatic equilibrium with thermodynamic equilibrium.
In thermodynamic equilibrium, all processes are occuring in a balanced way. Energy and matter are shifting back and forth via molecular collisions, photons, diffusion, etc, in a balanced way so that there is no net macroscopic change. It is not a complete absence of microscopic activity. Matter and energy spontaneously tend to diffuse from whereever they are, change form from whatever form they have, as allowed by a lack of kinetic barriers. In thermodynamic disequilibrium, their distributions are not equilibrium distributions, so there is more diffusing from one place or changing from one form than is diffusing or changing in the opposite direction – this drives the distributions toward thermodynamic equilbrium (which is not necessarily a homogeneous distribution because … gravity, etc.). The kinetic barriers or holes in those barriers work both ways and thus can’t spontaneously allow thermodynamic disequilibrium to increase in isolation. Of course, the approach to equillibrium of one system may drive some disequilibrium in another if they are coupled in a sufficient way. (PS macroscopic disequilibrium can be significant even if disequilbrium of small volumes is small – such that any small volume might be approximated as being at LTE and isothermal, etc.)
In climatic equilibrium (by metaphor, and literally as applied to hydrology) water flows into the top of a bucket at the same rate that it drains from the bottom of the bucket into another lower bucket, etc. Entropy is created in various places but doesn’t build up because the outflow is greater than inflow by that amount. In thermodynamic equilibrium, each bucket is floating within the next bucket, so the number of water molecules leaving each bucket hole is the same as that entering the same hole; there is no source of additional water and the outermost bucket has no hole.
Energy is flowing into the climate system as solar radiation (and geothermal and tidal energy, and of course meteors, other solar energy, other geologic energy, other stars, etc…, but those are generally so small for the Earth they can generally be ignored except very locally for some geothermal activity). From where it is absorbed it will build up until the concentration allows it to flow out at the same rate it enters. It will generally go through multiple steps before it leaves the system entirely (Setting aside conversion to mechanical energy and back, more such steps would tend to increase the temperature of the warmest parts, so that there are sufficient temperature differences to drive a sufficient net flux at each step). The greenhouse effect slows the outflow (by increasing the number of steps (decreasing the photon mean travel distance from emission to absorption) and/or by decreasing the window with a smaller number of steps (widenning the bands that block the warmest parts from emitting directly to space, etc.) without directly affecting the inflow (solar heating), so that concentration increases until sufficient to drive enough outflow to restore balance. A greenhouse effect can occur in solids such as on Triton (see S2E1 of “How the Universe Works”). If the Earth’s mantle were made transparent, the core-mantle boundary would cool dramatically. A winter coat slows the release of heat (radiative, sensible, and latent) from a person’s body. Etc.
In the global average, the surface of the Earth absorbs solar radiation and emits LW (longwave, a.k.a. terrestrial) radiation as well as sensible and latent heat (because pure radiative equilibrium would make the lower atmosphere unstable to convection, convection happens, so that the surface experiences net radiant heating and the troposphere experiences net radiant cooling. Greenhouse agents allow the troposphere to experience ongoing cooling, but without them all heat escaping the climate system would come directly from the surface – the surface would cool, and resulting changes in convection would cool part of the atmosphere (although parts of the atmosphere heated directly from the sun would tend to warm up). When a troposphere exists, convection tends to maintain an equilibrium lapse rate (generally), so the whole troposphere+surface shift in temperature in response to changes in net radiant outflow/inflow at the tropopause. The tropopause itself may shift in the process; if there is no troposphere then one could say the tropopause rests on the surface).
Solar heating of the ocean penetrates farther down than net LW cooling, and of course, evaporative cooling occurs at the surface – and that also increases density by increasing salinity; all of these processes would combine to drive convection in the uppermost ocean even without wind-driven mixing (although salinity can’t always be increased at the surface -there’s rain, etc.).
Anyway, the greenhouse effect most directly heats the ocean by decreasing net LW cooling at the surface; this would slow any upward heat transport to the surface (thermally-driven convection or forced convection by winds and their effects) from where solar heating occurs. Heat builds up until balance is restored (and mechanically-forced motions can push some heat downward).
Indirectly, changes in convection could also act to warm the ocean (reducing evaporative and/or sensible net cooling) – or they could cool the ocean – it depends – whatever happens the surface will tend to warm due to positive radiative forcing at the tropopause (see above).
*1*
– heat can spontaneously flow up a temperature gradient if it the enthalpy of some substance which is diffusing down a concentration gradient. For example, cold water may be farther cooled evaporatively by a warm air mass if the air is sufficiently dry. Ice was once made this way in ancient Persia.
– backradiation is allowed only in so much as radiation is allowed in the other direction at the same part of the spectrum; that amount will be a greater flux because of the temperature difference between surface and atmosphere. Even if surface emmissivity were low, the reduction in emission would be partly compensated by the reflection of backradiation, so the net flux will be from hot to cold. So long as emission and absorption occur at LTE and setting aside various oddball conditions (such as a rapid change in temperature relative to photon travel time), the net flux at any given frequency and polarization and direction (per unit solid angle) (emission into and absorption from), and thus in total (all frequencies, polarizations, and over a whole sphere of solid angle), from place (volume small enough to be isothermal) of emission to place of absorption, is always from hotter to colder, but it is generally the difference between two fluxes in opposite directions. Even more generally, one can assign a brightness temperature to any given population of photons sufficiently defined to be isothermal, and consider the net fluxes between photons and other matter, etc.
Patrick 027says
Re my 69, 64 re 55 Karsten V. Johansen –
CORRECTION: (I)PV is proportional to the absolute voriticity DIVIDED BY layer thickness (as mass per unit area; in a continuously stratified fluid, use mass per unit area per unit vertical change in potential density (or potential temperature)). (A thinner layer has ‘greater potential’ to have an increase in absolute vorticity by horizontal convergence, which requires layer thickenning.)
CLARIFICATION: When an (I)PV anomaly is produced by advection (transport) or some other process, an adjustment process tends to occur to restore or maintain a balance relationship between the flow and the layer thickness (via the thickness’s effect on pressure gradients) – this is the relationship that would be used to derive a velocity field from an (I)PV distribution. The adjustment process occurs because an imbalance leads to some (additional) acceleration; inertia-gravity waves are emitted in the process (the most familiar example of a gravity wave is probably water waves one would see in the ocean – those are surface waves; there are also internal waves occuring at sharp density changes within a fluid or occuring in continuously stratified fluids; the ‘inertia-‘ part comes from the coriolis effect, which is significant for low-frequency waves). The adjustment process involves horizontal convergence or divergence – taking into account planetary vorticity and conservation of angular momentum, convergence tends to make the flow’s relative vorticity more cyclonic.
Examples: – with no initial flow:
southward or northward displacements produce cyclonic or anticyclonic PV anomalies. Absolute vorticity would be conserved without some adjustment, so relative vorticity increases as planetary vorticity decreases with equatorward displacement. But this is not balanced without pressure variations. Divergence occurs to thin-out fluid layers, producing a low pressure center or line about which the flow is cyclonic; the flow is reduced in the process. (If in a continuously stratified fluid, the lowering pressure will produce (adiabatically) a cold region at lower levels; thus this is a cold-core low which must increase in strength away from the surface (or a warm-core high which does the same).)
over topography, downslope or upslope displamements produce cyclonic or anticyclonic (I)PV anomalies by producing regions with a thinner or thicker fluid layer. No velocity field is produced directly without adjustment. Convergence into a thinner region (with lower pressure) increases the pressure and thickness while increasing cyclonic relative vorticity. If occuring in a continuously stratified fluid, the effective IPV anomaly is really a potential density anomaly at the surface, and the anomaly’s flow pattern decreases in strength away from the surface (it would be a warm-core low or cold-core high).
“I ask because I’ve recently once again come across the claim that CO2 can’t warm the oceans because the downward IR won’t penetrate the ocean mm thick skin layer. Those waving this claim imply that there’s no other mechanism to warm the oceans.”
I came across something like this a few years back–basically, the author re-imagined “absorption/emission=reflection.”
Cuckoo.
Nick Gottssays
Can anyone point me to work on how long raised CO2 levels and ice-free conditions would last if we succeed in melting the polar ice-caps? I think I’ve seen something indicating this would be on the order of hundreds of thousands or millions of years, through increased weathering, as the orbital and inclination changes thought to be responsible for recent ice ages would be insufficient. Is this correct?
Thanks in advance.
Phil Scaddensays
Andrew W, Science of Doom goes into the detail of longwave heating the ocean here. HTH.
Patricksays
I would like to know if a small reduction of relevant observed rates of change (OHC or other) in the last decade is partially attributable to global (economic) recession. Is this a possibility, in principle?
[Response: No. The timescales for the carbon cycle and ocean thermal inertia are too long for any recent blips in emissions to have an effect. – gavin]
numerobissays
I’m seeing the bizarre claim that melting the ice cap will cool the Earth, bringing about an ice age. The “logic” is that with the ice cap melted, the Arctic ocean can let more heat escape which normally would be trapped under the ice. Obviously hogwash.
I do wonder: is there a sea temperature at the pole such that the ocean loses more heat in winter than it gains in summer?
David B. Bensonsays
Nick Gotts @80 — Next glacial is postponed for about 100,000 years. Arctic sea ice will return before then.
Susan Andersonsays
Thanks for the Jeremy Jackson reference, and to Russell for some alleviating and aggravating humor – bodacious Boadicea! http://vvattsupwiththat.blogspot.com/
patrick thanks also for your continuing efforts …
Susan Andersonsays
That is, Patrick027, didn’t want you to think I wasn’t still faintly pursuing knowledge.
Patrick 027says
Re 81 Phil Scadden (re Andrew W) – great link;
I just love this line in the comments responding to “tallbloke’:
“I don’t think you understand the scientific method because once you have done lots of experiments you can apply those results to new problems. That is what I have done here.”
PS I see Bryan is illustrating the case of one who doesn’t understand the 2nd Law fully, and especially in the case of radiation, or how the energy fluxes work; and he mentions’s ‘Gords solar heater’ – Gord has attained infamy, apparently. Without backradiation, an object isolated from the heat capacity of the rest of the surface material and amb-ient air, and kept out of the sun (or moonlight, etc.) will more quickly cool toward absolute zero (at lower temperatures, a small amount of radiant intensity can make a big difference in equilibrium temperature, though I’m not quantitatively familiar with moonlight in that context (well, same solid angle in sky, assuming Lambertian reflection, divide solar flux per unit area by (1 AU/solar radius)^2 and then account for albedo…). What a parabolic (or any approximating shape) can do is focus the darkness of the backradiation near zenith on an object (you don’t need precision optics in this case – unless you’re aiming at a small hole in the clouds (or between trees or skyscrapers) – because at least in clear sky conditions, the brightness temperature varies relatively gradually over angle). Absent an inversion of sufficient opacity, backradiation brightness and thus brightness temperature will decrease away from the horizon (you are looking through less air looking straight up, and the closer warmer layers block less of the greater darkness of the upper cooler layers – towards the atmospheric window, absent clouds, the whole atmosphere blocks less of the darkness of space.
PS I choose to stick with the greenhouse analogy. Energy out is of a different form than energy in, thus the fluxes can be regulated seperately in principle (setting aside the dual role of clouds, etc.); if you partially shut the outlet, energy builds up until it can force it’s way through fast enough to restore (a new) equilibrium.
Patrick 027says
Re Andrew W – there is of course the partially seperate matter of heating the deep ocean. Given sufficient time, absent any deep ocean mixing/convection, the temperature would tend towards nearly isothermal, with enough of a temperature gradient to support a geothermal heat flux from the seafloor. The deep ocean is kept cooler than that because deep water is generally formed in relatively cold conditions at the surface. If deep water forms under warmed conditions than an increase in temperature will eventually fill the ocean depths that way (and eventually affect the temperature of cold upwelling water). If deep water formation is simply shut off, than we’d have a somewhat (not sure just how much) more rapid warming toward an equilibrium climate. Wind-driven upwelling would still pull water up, where it would warm and eventually join the mixed layer, so warming could still happen that way. I’m not sure where the state of the science is on this, but I think there’s an idea that in the geologic past (Cretacious, I think), deep water formed from warm salty water masses at lower latitudes (today there is a contribution from Mediterranean water sinking into the Atlantic, though not all the way to the bottom).
Patrick 027says
Re Susan Anderson – thanks.
(re Russel – “Boudicca” :) – is the reference because of the spirals (Celtic art?) or is the name a common reference in the UK to any such sculpture? – just curious.)
Patrick 027says
Re my 86 “toward absolute zero” – make that something like 3 K (?) or whatever space is radiatively.
Earlier, Tyrrell et al 2007 examined this, concluding that we have already skipped the next glacial epoch. Furthermore, Tyrrell concludes that if we continue our present fossil fuel consumption, we will skip the next 5 glacial epochs. So no glacial epochs the next million years… http://plankt.oxfordjournals.org/content/30/2/141.full.pdf+html
There, the reader can see what else is being written, and follow up citing papers to see what else is being written.
Sites like Milloy’s offering a few selected copies of papers wrap them in PR spin that misleads the naive reader, rather than pointing to more resources.
MSsays
Nick Gotts @80
David Archers The Long Thaw is a very good read on the topic.
Susan Andersonsays
OT for Patrick027 and anyone interested:
Boudicca = Boadicea = warrior queen: “Boudica, also known as Boadicea and known in Welsh as Buddug was queen of the British Iceni tribe who led an uprising against the occupying forces of the Roman Empire.” Wikipedia, died AD 61, Britannia http://www.warlordgames.com/1250/queen-boadicea-rolls-up-and-more/
This is lots of fun but I mustn’t encourage anyone to join me in this timewasting activity: the images on my search are a real study
The idea of calling a repurposing of a slag heap an environmental mitigation is both humorous and appalling and I thought Russell nailed it.
Karsten V. Johansensays
RE 64, 69 and 78 Patrick 027:
Thank you for your efforts! – I’ll take some time to try to understand as much as I can.
My view is from the side of glaciation history etc. (Dansgaard-Oeschger
events, Younger Dryas etc.): what happens, when the North Atlantic Drift/
the thermohaline circulation (or at least parts of it)is “turned off” f.ex.
by a big input of (fresh) meltwater to the North Atlantic (or to the polar
basin)? Is it really possible to explain the huge temperature shifts
then suddenly arising with the theory of Seager? I mean, he has to take away (in his models) the Rockies to get cooling. But they were there almost unchanged during all the enourmous climate shifts during the quaternary. How will he then explain what happened, if his hypothesis about Western Europe’s climate is correct?
In O’Hare et al., “Weather, Climate and Climate Change” (Essex 2005), p. 70
they have a fig. 3.8 displaying the enormous temperature anomalies relative to latitude around the globe. There you can see, f.ex. that Norway (where I live), northern Scotland, eastern Iceland and the sea in between has a mean temperature anomaly for january relative to latitude of no less than plus 20 degrees C. This in contrast to the much smaller differences recognized by Seager in his modelling. At the same latitudes, western Canada/Alaska has an anomaly of just plus 12 degrees C (and covering a much smaller area). It seems that the fig. mentioned is almost the same at this
David Benson@84 and particularly Daniel Bailey@91 – thanks very much. The immediate trigger for the question was someone claiming that the next ice age would arrive on schedule despite AGW; but I’m also developing a scenario for a novel set partly some tens of thousands of years in the future, with melted ice-caps.
#87–“Backradiation” is a fascinating thing, to me at least, and observations can be made with no great level of technical sophistication. In fact, they were, and quite rigorously too, in the case of this classic of early climate science:
numerobis #83: I’m seeing the bizarre claim that melting the ice cap will cool the earth, bringing about an ice age
At first, yes, I think there will be some short-term cooling from the melting. It’s basic thermodynamics, in this case sort of an evaporative swamp cooler effect. Don’t know how much cooling though. However when the ice is gone then I’d expect temps to rise. My guess on the second part of your question about heat storage at the poles, I tend to think most of it is stored outside the poles in the lower latitudes. Others can correct me.
I wonder though how much extra warming there is each year after (and because of) the arctic ice disappearing.
I think you need a citation to explain “swamp cooling” whatever that might mean. Melting the ice caps isn’t going to cool the planet; it rearranges things somewhat.
The “ice age” notion is an exaggeration of the issues about changes in ocean circulation.
Effects of “adaptation” are strange and unpredictable. Maple syrup harvests in NE U.S. collapse, rising value of syrup leads to a vast theft of strategic reserves of maple syrup held by friendly neighbors to the north:
“The [Federation of Quebec Maple Syrup Producers] is currently evaluating the scope of the situation. The empty barrels found on site suggest that their contents had been emptied into other containers in view of illegal distribution. In total, the burglarized warehouse held over 10 million pounds of maple syrup amounting to over 30 million dollars in value.
The marketing of the stolen maple syrup will affect the entire maple industry. It is crucial to identify those responsible for this crime.
In addition, several American states saw a very low, indeed catastrophic, harvest during the 2012 season. The Quebec harvest, however, remained normal. The Federation`s maple syrup inventories supply markets during periods of weaker harvests and can, therefore, be considered a global strategic reserve.”
Quebec Maple Syrup Producers Robbed, $30 Million Worth Of Maple Syrup Stolen From Company Warehouse
Begin hording; I’m going to do a John Denver and install a storage tank in my yard.
Is there a futures market for this stuff?
Gavin – I do not know that you reduced any confusion among lay people like me. Trenberth said the additional heat being found in the oceans could come back to haunt us. I do not understand what you’ve said, but my hunch is you’re saying as long as the current energy imbalance exists, the system is gaining energy as time goes by. I assume you mean its moving around within the system does not count as a reappearance. If the energy imbalance were to go the other way, then I assume you mean the heat would reappear in terms of its imminent exit to space. If not that, I don’t have a clue what you mean.
[Response: I don’t know what Trenberth is referring to specifically i.e. whether he is speaking metaphorically or literally. But the Ocean Heat content increase is effectively irreversible. The heat being sequestered in the deep ocean is not coming back anytime in the next thousand years or so. – gavin]
How about the difficulty of heat getting -into- the ocean? How long before our charge card is impolitely declined when we present the tab for our ongoing drunken spree?
Bad metaphor actually; I suppose it’ll be more a matter of raised eyebrows and increasingly watered-down drinks, leading to a shocking hangover.
@50 Hank. It was my error. Got my Wa’s mixed up being a Brit and all.
Some days ago a leading newspaper in my country, “Aftenposten” (“The Evening Post”) presented the postulates in this article:
http://www.americanscientist.org/issues/id.999,y.2006,no.4,content.true,page.1,css.print/issue.aspx
in a very positive tone (but the journalist hadn’t understood any of the arguments in the article, it appeared. At least he wasn’t capable of presenting them to the public without wreaking heavoc to most of elementary atmosphere physics etc.)
I then read this article and understood a whole lot more, but still I must admit, that I’m not very convinced by the theory of mr. Seager.
Firstly I can’t understand what happens to the waves in the jet stream and to the polar front’s movements – they seem to disappear completely?
Secondly, he doesn’t offer any explanation for the causes of the younger dryas cooling, the sudden coolings during the Weichsel ice age etc. etc.
Thirdly he does’t seem to reflect on *what causes the cool airmasses arriving at the north american east coast to warm up again when crossing the Atlantic from southwest towards northeast, if not overwhelmingly the warm surface waters of the Gulf Stream and the north Atlantic Stream*?
Therefore Seager does not understand why the west coasts of Portugal, France, Ireland, Scotland and Norway are clearly warmer than the west coast parts of the north american continent at the same latitudes (f.ex. the alaskan west coast is considerably colder than the norwegian west coast as far as I know). In fact he does not mention or discuss these facts at all.
Some of his (?) figures seems somewhat enigmatic to me. Especially fig.s 5 and 6.
Could anyone of the experts here enlighten me/us a little about the subject and tell me where I (and/or f. ex. Wally Broecker here:
http://faculty.washington.edu/wcalvin/teaching/Broecker99.html ) may be mistaken?
Andrew W @40 — The heat transfer is rather insignificant.
Re: vukcevic @ 6 Sep 2012 5:06 PM
My beliefs in this regard are supported by your statements such as:
or this one:
I’m afraid that such statements do _not_ give me the impression that you agree with radiative forcing of anthropogenic CO2, or in fact any significant human influence on temperature changes.
Re Chris Korda @ 32 – in search of a distinction (this doesn’t address the whole of the two issues, one of which is mostly OT I believe and so I won’t add any more than what I previously said, which is…)
see this, which was a clarification/add on to what I meant by this (3rd paragraph), and this (2nd part) .
Re Hank Roberts @ 14 – I’ve now read the whole thing (sans many comments). Wow! (Part of that reaction due to my having had some similar thoughts** ((where is gar…) capitalism itself should have some *tendency* to put the ‘best/brightest’ in charge; aren’t labor unions a part of free enterprise? (natural law…) Humans are natural – ergo regulated and quasi-free markets are natural (as is love, as is war, …), etc.; (~CEOs/where is gar…) no matter how unregulated a market it, at some point sombody is allocating something; big business becomming sort of government…; etc.) But did I miss something – for whom was his blunt answer (or does it matter)?
**-planted in my mind when I read “Earth” when I was ~12/13-ish? Actually, “Complexity” probably had something to do with it, too… etc.
(One section reminded me of Fareed Zakaria’s “The Future of Freedom”)
Not sure if this is appropriate or not, but since it’s ‘Unforced Variations’…
I’ve just written a draft of a paper that will form a chapter of my economics PhD. It’s an economics of climate change paper and I’ll get plenty of comments from economists in the department. I’d be very interested in also getting comments from climate scientists though, especially on my accuracy in describing the position of climate scientists and the climate science ‘community’.
The paper can be viewed at https://docs.google.com/file/d/0BzDVHHWhre6mOU5JN3ctbkFYUGs/edit and I can be contacted at dcomerf_at_gmail.com
Re 52 JCH – my impression – though I may not have read enough of the original source – was that if temperature was not rising as rapidly because the ocean was heating up faster than expected for the time being, eventually this could stop and the temperature would rise faster (?) or maybe it was a reference to heat capacity in general (that there is ‘warming in the pipeline’).
Re 40 Andrew W – The water cycle is an important part (the larger part) of convective heat flux from the surface to the atmosphere, although net radiation is generally significant. I’m not sure if it makes sense to isolate one part like that, though. (from memory:) I think tropopause-level forcing for CO2 is greater than surface forcing; thus the atmosphere to some extent would tend to warm first and then a resulting reduction in (the vertical heat flux of) convection would lead to surface warming. However, the water vapor feedback is, I think, supposed to be stronger at the surface than at the tropopause, which would tend to lead to surface warming first, then an increase in convection… The ocean would generally be cooled by rain (which tends to be cooler than the air (unless the cloud touches the surface, there would tend to be some evaporative cooling of the rain; anyway it’s falling from higher-up and temperature tends to decrease with height (with the exception of fronts and the like (gust fronts), nocturnal inversions, etc.)). But except for snowfall, there is no latent heat uptake when the rain hits the surface, whereas there is evaporative cooling when the water goes back up, much larger than the sensible heat associated with a few K difference in temperature.
There is an upper mixed layer of the ocean which comes to equilibrium with climate forcing *relatively* fast due to *limited* heat capacity. Using τ = C/(B-F) = C*ECS , using ECS = 0.75 K*m^2/W and C ~= 200 MJ/(K*m^2), τ ~= 150 Ms ~= 5 years (That’s the e-folding time; you have to multiply it by some factor to get closer to equilibrium). That C is approximately what you’d get from a global 50 m deep layer of water (which would be a bit deeper when compressed into oceanic areas (I’ve seen different numbers given for the depth of the mixed layer – of course it varies regionally and seasonally). You only get roughly 10 MJ/(K*m^2) for sensible heat of the atmosphere; I think (from memory) the latent heat of additional water vapor is of a similar order of magnitude to that. Etc.) Exchange with the deeper ocean limits the rate of additional oceanic heating.
Re my last comment:
You only get roughly 10 MJ/(K*m^2)
Since the troposphere and stratosphere are going in opposite directions, you’d want to use tropospheric C (after stratospheric adjustment (to instantaneous forcing – there is some stratospheric response to surface+tropospheric warming too but I think it’s supposed to be small)), which I remember being something like 85 % of the atmosphere (by mass and thus by C).
And re my comment in July :
“It’s not like the Greenland ice sheet is now set to fall completely apart within a decade after one time with nearly all the surface near or above freezing, but it’s going to keep shrinking.” [new paragraph] “At least not for a very long time.” … that last part should have been in () and placed right after ‘within a decade’.
“
I ask because I’ve recently once again come across the claim that CO2 can’t warm the oceans because the downward IR won’t penetrate the ocean mm thick skin layer. Those waving this claim imply that there’s no other mechanism to warm the oceans.
[Response: Nonsense. And easily demonstrated nonsense at that – how do these people explain the increase in ocean heat content? Or even the everyday heat exchange that is ongoing all the time? Evidently there must be mechanisms that transfer heat between the atmosphere and ocean. You can see them in the wake of a hurricane – where wind stirring transfers warm water to depth, and then atmospheric fluxes restore the surface heat content. Those fluxes include solar radiation, latent and sensible heat as well as long wave radiation combined with mechanical stirring from winds and waves. – gavin]
Re 55 Karsten V. Johansen – I’m not sure specifically about the size of the role of the Gulf Stream in heating Europe vs Kuroshio heating the Pacific Northwest, but the explanation of atmospheric waves made sense to me.
Specifically, the momentum equations for a fluid on a rotating planet can be analyzed and it can be shown that, absent viscous or diabatic processes (radiant or sensible or latent, or frictional (or for that matter, chemical, electical, or nuclear) net heating or cooling, or mixing, as opposed to adiabatic temperatue changes), and with some simplifying approximations (ignore the small ‘curvature terms’), using potential temperature as a vertical coordinate, there is a quantity called potential vorticity (PV) which is conserved following fluid motion. This is the measure of angular momentum mentioned in the “American Scientist” article – with a clarification – the article seems to be describing a barotropic version, which applies to an unstratified fluid layer.
PV is proportional to absolute vorticity divided by fluid layer thickness (since mass is conserved, the fluid layer thickness is in terms of mass per unit area. If the situation allows an approximation of incompressibility, then volume per unit area (or just depth) can be used instead). Sticking with the vertical component of vorticity, absolute vorticity is equal to planetary vorticity (the vorticity of the rotation of the solid Earth about the local vertical, which is proportional to the sine of the latitude and happens to be equal to the coriolis parameter f (for just horizontal components, coriolis acceleration = f*(cross product of velocity and a unit vector pointing up), and the relative vorticity, which is the vorticity of the wind (or currents) – this actually has two parts: a curvature/orbital vorticity (requires a curvature of streamlines) and shear vorticity (the change in speed across streamlines). In a stratified fluid, the rate of change of pressure relative to potential density (or potential temperature in the atmosphere) can play the role of fluid layer thickness in the proportionality with PV – which may then be called ‘IPV’ or ‘isentropic potential vorticity’.
(PS potential temperature is the temperature that a substance will have if brought adiabatically to a reference pressure. The potential density is the density it would then have. In the above, potential density must be used in the ocean because changes in salinity can affect it independently of potential temperature. Variations in water vapor and liquid water content in clouds can do this in the atmosphere but they tend to have small effects on density for familiar conditions and can for some purposes be ignored.)
PV and IPV are very powerful concepts – it is possible, with boundary conditions and an assumed relationship (like geostrophy or gradient wind balance) to reconstruct a flow pattern from an IPV distribution, and with the assumption that IPV is conserved, the flow pattern determines how IPV is redistributed.
…
dcomerf @60 — Your paper seems largely sensible to this amateur. However, it is quite clear that a rapid warming of even just 2 degrees Celcius (2 K) will place great stresses on the living environment, so great (I think) as to constitute a catastrophe. One should think in terms of geologic time; from Present (1950 CE) until that 2 K of warming is but an instant of geologic time and in that sense is already a forseeable catastrophic tipping point.
Indeed I think we are more than half way (measured from Present) to a mere 1 K warming and Terra has already experienced economically quite damaging events in various regions; at a 1 K warming it will be rather terrible. So I opine that a 2 K goal is far, far too large to be bourne.
One useful book to read is Mark Lynas’s “Six Degrees”:
http://www.marklynas.org/2007/4/23/six-steps-to-hell-summary-of-six-degrees-as-published-in-the-guardian
My understanding of “ocean heat” is as follows:
The problem is not that there is heat in the ocean, but rather that there ISN’T heat in the ocean (yet).
(Using the common informal meaning of “heat” as energy or temperature, not the formal thermodynamic definition as energy flow from temperature difference!)
The ocean is accumulating energy at present, and the rate at which energy is being accumulated through heating of the ocean is effectively equal to the difference between what energy Earth absorbs from the Sun, and what energy it emits back to space. The energy imbalance at the Top Of Atmosphere, in other words.
There are two major significant drivers of the energy imbalance at present times. One is the increasing atmospheric greenhouse effect, which means that less energy gets out to space for a given surface temperature. The other is the increasing surface temperature, which increases the energy out into space. These will, eventually, come into approximate balance. Right now, they are not.
It’s technically incorrect to say that there’s some kind of energy in the ocean now which is going to be a problem later. What there is in the ocean is an energy flux (or energy per unit time) that is now going into heating of the ocean. There’s an energy flux down into the ocean which eventually, as the Earth gets back into approximate equilibrium sometime in the future, will be an energy flux back out into space, driven by a higher surface temperature and a warmer ocean.
This is also called “warming in the pipeline”.
Thermodynamic terminology is a pain. (And I’ve done the usual thing here with technical misuse of the term “heat”.) I can see how someone might speak of ocean heat coming back to haunt us. There is a flow of energy into the ocean which is going to result in temperature changes in the future; and we can’t avoid that. It’s already implicit in the CURRENT atmospheric greenhouse. Stopping atmospheric changes right now would still mean that flow of heat into the ocean is going to bring about increasing temperatures in the future.
But it’s really easy to get mixed up in terminology.
Have I got the picture about right there?
> is now
since when?
Re 63 response: Of course it’s nonsense, so here’s an example:
http://hockeyschtick.blogspot.co.nz/2012/09/realclimate-admits-doubling-co2-could.html?showComment=1347069693622#c6797830367100011387
Re 55 Karsten V. Johansen (cont.) …
(PS it is possible for an adiabatic process to include latent heating/cooling. Due to the kinetics of phase changes (nucleation, diffusion of matter and energy down gradients), etc (activation energy where chemical reactions are involved), some entropy will be produced, but if the approach to thermodynamic equilibrium is sufficiently fast relative to pressure changes, the process can be approximated as isentropic (reversable, and adiabatic). However, in the atmosphere, it is potential temperature defined by dry (no condensation/evaporation etc.) adiabatic processes that tends to either increase with height or stay constant in mixed layers, and the seperation of condensed water from the air in which it condensed generally leads to irreversability (gain in entropy, non-adiabatic), so it is convenient to distinguish between dry adiabatic and moist adiabatic processes), and it is easier to describe IPV using potential temperature defined by dry adiabatic processes as a vertical coordinate.)
…
Anyway, the flow (wind/current velocity field) and (I)PV can be described as sums of components, such as anomalies plus some background/basic/reference state. Within each group (velocity and PV seperately), they add linearly to the total, but (I think**) the relationship between a PV anomaly and the velocity field associated with it can depend on the rest of the components, although linear superposition can be a good approximation for weak anomalies.
The velocity field around a (anti)cyclonic PV anomaly will itself be (anti)cyclonic; if the PV anomaly is of limited extent, the velocity anomaly can extend beyond the PV anomaly. A relatively horizontally large PV anomaly with sharp edges can have a calm central area with a jet-like flow around its boundary. Jets in general are associated with sharper PV gradients.
Because of the distribution of planetary vorticity (which is to a very very good approximation, constant), (I)PV generally tends to become more cyclonic towards the poles. With this gradient direction, if (I)PV contours are brought closer together, eastward (westerly) flows occur; if farther apart, flow may be in the opposite direction (or if relatively farther apart, flow may be westerly but weaker).
With such a north-south PV gradient, North-south displacments of fluid produce PV anomalies, which induce relative vorticity anomalies and associated flow patterns. A wavy displacment field causes a flow field that acts to produce a wavy displacment field that is shifted from the original; the overall effect is that (I)PV anomalies propagate in the presence of a background (I)PV gradient, giving rise to ‘vorticity waves’.
Setting aside the flow pattern, regions of thinner fluid layers tend to have larger (I)PV; this can be from underlying topography, or variations in the top of the fluid layer. In a stratified fluid, one can think of many layers that each thin-out approaching an underlying or overlying boundary – thus, gradients in potential density at a boundary are like IPV gradients and in fact, using the same relationship (geostrophy or gradient-wind balance), surface potential they induce flow patterns like IPV anomalies do (consider the flow pattern associated with the IPV anomaly across the other side of the boundary that would be necessary to induce the potential density anomaly itself).
Any such PV (or surface potential density) gradient can support vorticity waves. Phase propagation is always directed with increasing cyclonic PV to the right (at some angle), but a region of wave activity propagates with group velocity, which depends on the orientation of the waves and the wavelength – in a stratified fluid it can have vertical as well as horizontal components.
Waves can produce velocity fields that extend into regions of opposing (I)PV gradients, where there can be counter-propagating waves. These waves can interact – for a range of wavelengths and other conditions, they will act to maintain a phase relationship that leads to mutual amplification. With surface potential temperature tending to increase equatorward and cyclonic IPV in the atmosphere tending to increase poleward, such counterpropagating waves can occur and grow (via baroclinic instability).
The waves discussed in the article are of the ‘quasi-stationary’ sort. The wavelengths are too long to maintain a phase relationship required for baroclinic instability. A freely propagating quasi-stationary wave has sufficient wavelength to be able to propagate (refering to phase propagation) through the air with a speed similar to the speed the air is moving (and in the opposite direction). If air is flowing over topography, a voricity wave can be forced (it will tilt back into the flow with height so that the group velocity is away from the source (although this tilt may be small within a given vertical extent, such as in the troposphere, I think**); this transports a momentum flux upward, so that the tendency for topography to impeed flow can bypass intermediate layers and act to slow down flow at some higher level where the wave amplitude leads to nonlinear wave breaking (see ‘sudden stratospheric warming’). I think (from memory**) the wave response to flow over topography is supposed to be largest near wavelengths which would freely propagate in the opposite direction at the same speed (resonance). While phase propagation is limited in direction, a global wave pattern can form as wave activity spreads out with group velocities of a spectrum of forced waves; this behavior can also result from wave forcing by diabatic anomalies, such as atmospheric heating over a warm SST anomaly (see also ‘ENSO’).
Baroclinic waves aren’t eliminated from this picture; they occur on top of it (although I think they interact with it too. Extratropical storm track activity produces momentum fluxes as well as heat fluxes, which reshape the PV distribution, etc.)
Oceanic gyres can also be described in terms of PV. I think they might be described as standing vorticity waves.
Of course diabatic and viscous processes occur, but these don’t generally mask such behavior, they just modify it (or in some cases, force it).
Hank asks in #67:
>> is now
> since when?
It’s tough to know who you are asking; but since I used the phrase “is now” in the prior comment #66, I’ll take a stab:
I said:
> What there is in the ocean is an energy flux (or energy per unit time) that is now going into heating of the ocean.
The present imbalance and consequent flow of heat into the ocean has most likely been since the mid twentieth century, I think. Sorry if I picked the wrong “is now”.
Chris Ho-Stuart, what you are saying makes no sense to me. If the system is in equilibrium, would not OHC remain roughly the same? What I have been imaging is equilibrium means the heat going into the oceans would equal the heat leaving the oceans.
The way I understand it, that would be the point where the pipeline runs dry. The warming would be over with. The enhanced greenhouse effect would have finished its job of bringing the earth’s system into balance.
When Trenberth made his comment I figured he meant natural variation, in the form of El Nino, would lead to 1998-style boosts in the GMT. My assumption has been that during a El Nino heat leaves the ocean and warms the SAT. I’m starting to doubt this now.
In 1998, if not from the oceans, from where did the additional warmth come?
[Response: There are obviously anomalous fluxes to and from the ocean due to ENSO – though the numbers are small in the aggregate. But ENSO is mainly an upper ocean phenomenon and does not show up much (if at all) in even the 0-700m ocean heat content record (unlike volcanoes, whose effects are clear). – gavin]
Paul @28 –
“US commitment would have been a reduction, by 2012, to 93% of 1990 levels.” Extended by Rio to 2017-2020. They’ll probably make it.
“2010 US emissions were 112% or 114% of 1990 levels”
Baseline of early 90s was 1992. The decline for 2010-2012 is pronounced.
“Obviously the proof will be in 2012 annual emissions figures ”
The proof of the ‘make by accident’ will be in 2017. The benny would be making it by 2015, and taking a miraculous leadership revival role.
The criticism of 1st-quarter is unwarranted, since it’s a quarter-over-quarter comparison. However, the trend and flow shows the same thing in the Economist article:
http://www.economist.com/blogs/schumpeter/2012/05/americas-falling-carbon-dioxide-emissions
Candide @30. “if the reduction in CO2 emissions isn’t being offset entirely by increased methane emission ”
Methane is the combustion input, not the pollution by-product.
“It is very clear that combustion of natural gas in power plants produces substantially less — about half — the carbon dioxide (CO2) that is produced by a coal fired power plant for the same amount of electricity produced.”
http://tinyurl.com/99w43ez
Although the step is a huzzah, environmental concerns continue about precombustion escape in seepage, pipelines, and storage:
http://www.ipsnews.net/2012/06/u-s-sees-greatest-reduction-in-co2-emissions/
Gasland is good, but two Cornell studies have come out recently – one has an estimate of 7.9% with a second-study rebuttal of less than 2%:
http://www.bloomberg.com/news/2012-07-10/cornell-researcher-rebuts-colleagues-on-fracking-leaks.html
The EPA has already enacted legislation that is aimed at carcinogen agents, but has a ripple effect of reducing methane escape.
It isn’t perfect, but it’s world-wide headlines, and it’s one of the biggest pushback against rising GHG emissions to date.
Apologies to both posters for the delayed response.
As wind affects Earth’s rotation thus the length of a day, and storms are expected to strengthen the warmer it gets, wouldn’t this be evidence that climate change really will mess up your days? Okay, by fractions of a millisecond, but…
Andrew W., Is it your correspondent’s contention that the skin layer is a static boundary layer? Has [edit] he ever been to the ocean? Does he not realize that there are these things called “waves” and “wind” that are continually breaking up the surface layer?
[edit – less name calling please]
Re: #57 KR says: 7 Sep 2012 at 5:40 PM
KR (It would be nice to know to whom one is addressing, feels a bit odd communicating to a couple of letters)
You say: I’m afraid that such statements …….
KR, there is noting to be afraid of
My website contains more than 300 graphs (not all listed) of various ‘correlations’ some true some coincidental. Some data show long term temperature changes natural or forced and some none, here are two examples from the longest and the most scrutinized temperature records:
http://www.vukcevic.talktalk.net/CET-Jun.htm
http://www.vukcevic.talktalk.net/CET-NAP.htm
Now compare two sections from the second graph
http://www.vukcevic.talktalk.net/CET1690-1960.htm
coincidence? Maybe, or maybe not.
The graph you quote
http://www.vukcevic.talktalk.net/GSC1.htm
It shows de-trended values not anomalies, either data is wrong (from giss, noa, sidc and ethz all world reputable institutions), my email is on the graph so if you request more details, I shall be happy to provide it, for any of the above.
As far as raditive forcing of GHG is concerned multitude of expert opinions is available, my interest is natural i.e.unfoced variations as the thread suggests.
Dr. Schmidt and I went to the same university (albeit different degrees, mine is only an MSc in applied engineering) but that is not reason that we should agree. We look at the same data from different stand point of view and get to different conclusions.
KR, as I said , there is noting to be afraid of about that.
Apologies if this has already been posted.
asl.umbc.edu/pub/yurganov/methane/YurganovCCL.pdf
Takeaway line (for me, at least):
“The main conclusion of this paper is a qualitative detection of high and over the years increasing methane mixing ratios in areas coinciding with predicted locations of methane hydrates.”
Sounds like pretty good evidence that methane hydrate release has begun and is accelerating. The main question now is what is the rate of accelerate, and will that rate be further increased by a newly ice-free (or nearly so) Arctic Ocean.
Re 63,68 Andrew W –
You’ll find people who don’t get how the climate system’s energy fluxes work in equilibrium, so they will have trouble imagining how disequilibrium works too. Some will say that the 2nd law of thermodynamics forbids heat to flow from cold to hot and thus backradiation can’t exist (untrue in two ways*1*), or that the greenhouse effect amounts to a perpetual motion machine and suggests that you could put something in a microwave and have it heat itself up with no added energy, etc. Perhaps some of the confusion is based on mixing up climatic equilibrium with thermodynamic equilibrium.
In thermodynamic equilibrium, all processes are occuring in a balanced way. Energy and matter are shifting back and forth via molecular collisions, photons, diffusion, etc, in a balanced way so that there is no net macroscopic change. It is not a complete absence of microscopic activity. Matter and energy spontaneously tend to diffuse from whereever they are, change form from whatever form they have, as allowed by a lack of kinetic barriers. In thermodynamic disequilibrium, their distributions are not equilibrium distributions, so there is more diffusing from one place or changing from one form than is diffusing or changing in the opposite direction – this drives the distributions toward thermodynamic equilbrium (which is not necessarily a homogeneous distribution because … gravity, etc.). The kinetic barriers or holes in those barriers work both ways and thus can’t spontaneously allow thermodynamic disequilibrium to increase in isolation. Of course, the approach to equillibrium of one system may drive some disequilibrium in another if they are coupled in a sufficient way. (PS macroscopic disequilibrium can be significant even if disequilbrium of small volumes is small – such that any small volume might be approximated as being at LTE and isothermal, etc.)
In climatic equilibrium (by metaphor, and literally as applied to hydrology) water flows into the top of a bucket at the same rate that it drains from the bottom of the bucket into another lower bucket, etc. Entropy is created in various places but doesn’t build up because the outflow is greater than inflow by that amount. In thermodynamic equilibrium, each bucket is floating within the next bucket, so the number of water molecules leaving each bucket hole is the same as that entering the same hole; there is no source of additional water and the outermost bucket has no hole.
Energy is flowing into the climate system as solar radiation (and geothermal and tidal energy, and of course meteors, other solar energy, other geologic energy, other stars, etc…, but those are generally so small for the Earth they can generally be ignored except very locally for some geothermal activity). From where it is absorbed it will build up until the concentration allows it to flow out at the same rate it enters. It will generally go through multiple steps before it leaves the system entirely (Setting aside conversion to mechanical energy and back, more such steps would tend to increase the temperature of the warmest parts, so that there are sufficient temperature differences to drive a sufficient net flux at each step). The greenhouse effect slows the outflow (by increasing the number of steps (decreasing the photon mean travel distance from emission to absorption) and/or by decreasing the window with a smaller number of steps (widenning the bands that block the warmest parts from emitting directly to space, etc.) without directly affecting the inflow (solar heating), so that concentration increases until sufficient to drive enough outflow to restore balance. A greenhouse effect can occur in solids such as on Triton (see S2E1 of “How the Universe Works”). If the Earth’s mantle were made transparent, the core-mantle boundary would cool dramatically. A winter coat slows the release of heat (radiative, sensible, and latent) from a person’s body. Etc.
In the global average, the surface of the Earth absorbs solar radiation and emits LW (longwave, a.k.a. terrestrial) radiation as well as sensible and latent heat (because pure radiative equilibrium would make the lower atmosphere unstable to convection, convection happens, so that the surface experiences net radiant heating and the troposphere experiences net radiant cooling. Greenhouse agents allow the troposphere to experience ongoing cooling, but without them all heat escaping the climate system would come directly from the surface – the surface would cool, and resulting changes in convection would cool part of the atmosphere (although parts of the atmosphere heated directly from the sun would tend to warm up). When a troposphere exists, convection tends to maintain an equilibrium lapse rate (generally), so the whole troposphere+surface shift in temperature in response to changes in net radiant outflow/inflow at the tropopause. The tropopause itself may shift in the process; if there is no troposphere then one could say the tropopause rests on the surface).
Solar heating of the ocean penetrates farther down than net LW cooling, and of course, evaporative cooling occurs at the surface – and that also increases density by increasing salinity; all of these processes would combine to drive convection in the uppermost ocean even without wind-driven mixing (although salinity can’t always be increased at the surface -there’s rain, etc.).
Anyway, the greenhouse effect most directly heats the ocean by decreasing net LW cooling at the surface; this would slow any upward heat transport to the surface (thermally-driven convection or forced convection by winds and their effects) from where solar heating occurs. Heat builds up until balance is restored (and mechanically-forced motions can push some heat downward).
Indirectly, changes in convection could also act to warm the ocean (reducing evaporative and/or sensible net cooling) – or they could cool the ocean – it depends – whatever happens the surface will tend to warm due to positive radiative forcing at the tropopause (see above).
*1*
– heat can spontaneously flow up a temperature gradient if it the enthalpy of some substance which is diffusing down a concentration gradient. For example, cold water may be farther cooled evaporatively by a warm air mass if the air is sufficiently dry. Ice was once made this way in ancient Persia.
– backradiation is allowed only in so much as radiation is allowed in the other direction at the same part of the spectrum; that amount will be a greater flux because of the temperature difference between surface and atmosphere. Even if surface emmissivity were low, the reduction in emission would be partly compensated by the reflection of backradiation, so the net flux will be from hot to cold. So long as emission and absorption occur at LTE and setting aside various oddball conditions (such as a rapid change in temperature relative to photon travel time), the net flux at any given frequency and polarization and direction (per unit solid angle) (emission into and absorption from), and thus in total (all frequencies, polarizations, and over a whole sphere of solid angle), from place (volume small enough to be isothermal) of emission to place of absorption, is always from hotter to colder, but it is generally the difference between two fluxes in opposite directions. Even more generally, one can assign a brightness temperature to any given population of photons sufficiently defined to be isothermal, and consider the net fluxes between photons and other matter, etc.
Re my 69, 64 re 55 Karsten V. Johansen –
CORRECTION: (I)PV is proportional to the absolute voriticity DIVIDED BY layer thickness (as mass per unit area; in a continuously stratified fluid, use mass per unit area per unit vertical change in potential density (or potential temperature)). (A thinner layer has ‘greater potential’ to have an increase in absolute vorticity by horizontal convergence, which requires layer thickenning.)
CLARIFICATION: When an (I)PV anomaly is produced by advection (transport) or some other process, an adjustment process tends to occur to restore or maintain a balance relationship between the flow and the layer thickness (via the thickness’s effect on pressure gradients) – this is the relationship that would be used to derive a velocity field from an (I)PV distribution. The adjustment process occurs because an imbalance leads to some (additional) acceleration; inertia-gravity waves are emitted in the process (the most familiar example of a gravity wave is probably water waves one would see in the ocean – those are surface waves; there are also internal waves occuring at sharp density changes within a fluid or occuring in continuously stratified fluids; the ‘inertia-‘ part comes from the coriolis effect, which is significant for low-frequency waves). The adjustment process involves horizontal convergence or divergence – taking into account planetary vorticity and conservation of angular momentum, convergence tends to make the flow’s relative vorticity more cyclonic.
Examples: – with no initial flow:
southward or northward displacements produce cyclonic or anticyclonic PV anomalies. Absolute vorticity would be conserved without some adjustment, so relative vorticity increases as planetary vorticity decreases with equatorward displacement. But this is not balanced without pressure variations. Divergence occurs to thin-out fluid layers, producing a low pressure center or line about which the flow is cyclonic; the flow is reduced in the process. (If in a continuously stratified fluid, the lowering pressure will produce (adiabatically) a cold region at lower levels; thus this is a cold-core low which must increase in strength away from the surface (or a warm-core high which does the same).)
over topography, downslope or upslope displamements produce cyclonic or anticyclonic (I)PV anomalies by producing regions with a thinner or thicker fluid layer. No velocity field is produced directly without adjustment. Convergence into a thinner region (with lower pressure) increases the pressure and thickness while increasing cyclonic relative vorticity. If occuring in a continuously stratified fluid, the effective IPV anomaly is really a potential density anomaly at the surface, and the anomaly’s flow pattern decreases in strength away from the surface (it would be a warm-core low or cold-core high).
“I ask because I’ve recently once again come across the claim that CO2 can’t warm the oceans because the downward IR won’t penetrate the ocean mm thick skin layer. Those waving this claim imply that there’s no other mechanism to warm the oceans.”
I came across something like this a few years back–basically, the author re-imagined “absorption/emission=reflection.”
Cuckoo.
Can anyone point me to work on how long raised CO2 levels and ice-free conditions would last if we succeed in melting the polar ice-caps? I think I’ve seen something indicating this would be on the order of hundreds of thousands or millions of years, through increased weathering, as the orbital and inclination changes thought to be responsible for recent ice ages would be insufficient. Is this correct?
Thanks in advance.
Andrew W, Science of Doom goes into the detail of longwave heating the ocean
here. HTH.
I would like to know if a small reduction of relevant observed rates of change (OHC or other) in the last decade is partially attributable to global (economic) recession. Is this a possibility, in principle?
[Response: No. The timescales for the carbon cycle and ocean thermal inertia are too long for any recent blips in emissions to have an effect. – gavin]
I’m seeing the bizarre claim that melting the ice cap will cool the Earth, bringing about an ice age. The “logic” is that with the ice cap melted, the Arctic ocean can let more heat escape which normally would be trapped under the ice. Obviously hogwash.
I do wonder: is there a sea temperature at the pole such that the ocean loses more heat in winter than it gains in summer?
Nick Gotts @80 — Next glacial is postponed for about 100,000 years. Arctic sea ice will return before then.
Thanks for the Jeremy Jackson reference, and to Russell for some alleviating and aggravating humor – bodacious Boadicea!
http://vvattsupwiththat.blogspot.com/
patrick thanks also for your continuing efforts …
That is, Patrick027, didn’t want you to think I wasn’t still faintly pursuing knowledge.
Re 81 Phil Scadden (re Andrew W) – great link;
I just love this line in the comments responding to “tallbloke’:
“I don’t think you understand the scientific method because once you have done lots of experiments you can apply those results to new problems. That is what I have done here.”
PS I see Bryan is illustrating the case of one who doesn’t understand the 2nd Law fully, and especially in the case of radiation, or how the energy fluxes work; and he mentions’s ‘Gords solar heater’ – Gord has attained infamy, apparently. Without backradiation, an object isolated from the heat capacity of the rest of the surface material and amb-ient air, and kept out of the sun (or moonlight, etc.) will more quickly cool toward absolute zero (at lower temperatures, a small amount of radiant intensity can make a big difference in equilibrium temperature, though I’m not quantitatively familiar with moonlight in that context (well, same solid angle in sky, assuming Lambertian reflection, divide solar flux per unit area by (1 AU/solar radius)^2 and then account for albedo…). What a parabolic (or any approximating shape) can do is focus the darkness of the backradiation near zenith on an object (you don’t need precision optics in this case – unless you’re aiming at a small hole in the clouds (or between trees or skyscrapers) – because at least in clear sky conditions, the brightness temperature varies relatively gradually over angle). Absent an inversion of sufficient opacity, backradiation brightness and thus brightness temperature will decrease away from the horizon (you are looking through less air looking straight up, and the closer warmer layers block less of the greater darkness of the upper cooler layers – towards the atmospheric window, absent clouds, the whole atmosphere blocks less of the darkness of space.
PS I choose to stick with the greenhouse analogy. Energy out is of a different form than energy in, thus the fluxes can be regulated seperately in principle (setting aside the dual role of clouds, etc.); if you partially shut the outlet, energy builds up until it can force it’s way through fast enough to restore (a new) equilibrium.
Re Andrew W – there is of course the partially seperate matter of heating the deep ocean. Given sufficient time, absent any deep ocean mixing/convection, the temperature would tend towards nearly isothermal, with enough of a temperature gradient to support a geothermal heat flux from the seafloor. The deep ocean is kept cooler than that because deep water is generally formed in relatively cold conditions at the surface. If deep water forms under warmed conditions than an increase in temperature will eventually fill the ocean depths that way (and eventually affect the temperature of cold upwelling water). If deep water formation is simply shut off, than we’d have a somewhat (not sure just how much) more rapid warming toward an equilibrium climate. Wind-driven upwelling would still pull water up, where it would warm and eventually join the mixed layer, so warming could still happen that way. I’m not sure where the state of the science is on this, but I think there’s an idea that in the geologic past (Cretacious, I think), deep water formed from warm salty water masses at lower latitudes (today there is a contribution from Mediterranean water sinking into the Atlantic, though not all the way to the bottom).
Re Susan Anderson – thanks.
(re Russel – “Boudicca” :) – is the reference because of the spirals (Celtic art?) or is the name a common reference in the UK to any such sculpture? – just curious.)
Re my 86 “toward absolute zero” – make that something like 3 K (?) or whatever space is radiatively.
@ Nick Gotts
We know that, per Tzedakis et al 2012, “glacial inception would require CO2 concentrations below preindustrial levels of 280 ppmv” (for reference, we are at about 394 right now…and climbing).
http://junksciencecom.files.wordpress.com/2012/01/nature-geoscience-ice-age.pdf
Earlier, Tyrrell et al 2007 examined this, concluding that we have already skipped the next glacial epoch. Furthermore, Tyrrell concludes that if we continue our present fossil fuel consumption, we will skip the next 5 glacial epochs. So no glacial epochs the next million years…
http://plankt.oxfordjournals.org/content/30/2/141.full.pdf+html
> junkscience
Consider the context; be wary of where you find it and what’s lacking there.
When you point to copies of papers it’s always better to point to the original.
There, the reader can see what else is being written, and follow up citing papers to see what else is being written.
Sites like Milloy’s offering a few selected copies of papers wrap them in PR spin that misleads the naive reader, rather than pointing to more resources.
Nick Gotts @80
David Archers The Long Thaw is a very good read on the topic.
OT for Patrick027 and anyone interested:
Boudicca = Boadicea = warrior queen: “Boudica, also known as Boadicea and known in Welsh as Buddug was queen of the British Iceni tribe who led an uprising against the occupying forces of the Roman Empire.” Wikipedia, died AD 61, Britannia
http://www.warlordgames.com/1250/queen-boadicea-rolls-up-and-more/
This is lots of fun but I mustn’t encourage anyone to join me in this timewasting activity: the images on my search are a real study
The idea of calling a repurposing of a slag heap an environmental mitigation is both humorous and appalling and I thought Russell nailed it.
RE 64, 69 and 78 Patrick 027:
Thank you for your efforts! – I’ll take some time to try to understand as much as I can.
My view is from the side of glaciation history etc. (Dansgaard-Oeschger
events, Younger Dryas etc.): what happens, when the North Atlantic Drift/
the thermohaline circulation (or at least parts of it)is “turned off” f.ex.
by a big input of (fresh) meltwater to the North Atlantic (or to the polar
basin)? Is it really possible to explain the huge temperature shifts
then suddenly arising with the theory of Seager? I mean, he has to take away (in his models) the Rockies to get cooling. But they were there almost unchanged during all the enourmous climate shifts during the quaternary. How will he then explain what happened, if his hypothesis about Western Europe’s climate is correct?
In O’Hare et al., “Weather, Climate and Climate Change” (Essex 2005), p. 70
they have a fig. 3.8 displaying the enormous temperature anomalies relative to latitude around the globe. There you can see, f.ex. that Norway (where I live), northern Scotland, eastern Iceland and the sea in between has a mean temperature anomaly for january relative to latitude of no less than plus 20 degrees C. This in contrast to the much smaller differences recognized by Seager in his modelling. At the same latitudes, western Canada/Alaska has an anomaly of just plus 12 degrees C (and covering a much smaller area). It seems that the fig. mentioned is almost the same at this
http://books.google.no/books?id=-Y7Ayiyolh4C&printsec=frontcover&hl=no#v=onepage&q&f=false (p. 282, fig. 27-8) but with the temperatures in F in stead of C.
David Benson@84 and particularly Daniel Bailey@91 – thanks very much. The immediate trigger for the question was someone claiming that the next ice age would arrive on schedule despite AGW; but I’m also developing a scenario for a novel set partly some tens of thousands of years in the future, with melted ice-caps.
#87–“Backradiation” is a fascinating thing, to me at least, and observations can be made with no great level of technical sophistication. In fact, they were, and quite rigorously too, in the case of this classic of early climate science:
http://doc-snow.hubpages.com/hub/Global-Warming-Science-In-The-Age-Of-Washington-And-Jefferson-William-Charles-Wells
An incomplete history of succeeding work in the area can be found here:
http://doc-snow.hubpages.com/hub/Fire-From-Heaven-Climate-Science-And-The-Element-Of-Life-Part-Two-The-Cloud-By-Night
numerobis #83: I’m seeing the bizarre claim that melting the ice cap will cool the earth, bringing about an ice age
At first, yes, I think there will be some short-term cooling from the melting. It’s basic thermodynamics, in this case sort of an evaporative swamp cooler effect. Don’t know how much cooling though. However when the ice is gone then I’d expect temps to rise. My guess on the second part of your question about heat storage at the poles, I tend to think most of it is stored outside the poles in the lower latitudes. Others can correct me.
I wonder though how much extra warming there is each year after (and because of) the arctic ice disappearing.
I think you need a citation to explain “swamp cooling” whatever that might mean. Melting the ice caps isn’t going to cool the planet; it rearranges things somewhat.
The “ice age” notion is an exaggeration of the issues about changes in ocean circulation.
Try here: http://scholar.google.com/scholar?as_ylo=2012&hl=en&as_sdt=2005&sciodt=0,5&cites=9655729569414500406&scipsc=
Thanks to MS@93 as well – David Archer’s book looks like essential research material if i’m ever going to write my novel!