A lot has been made of a paper (Lyman et al, 2006) that appeared last year that claimed that the oceans had, contrary to expectation, cooled over the period 2003-2005. At the time, we (correctly) pointed out that this result was going to be hard to reconcile with continued increases in sea level rise (driven in large part by thermal expansion effects), and that there may still be issues with way that the new ARGO floats were being incorporated into the ocean measurement network. Now it seems as if there is a problem in the data and in the latest analysis, the cooling has disappeared.
Ocean heat content changes are potentially a great way to evaluate climate model results that suggest that the planet is currently significantly out of equilibrium (i.e. it is absorbing more energy than it is emitting). However, the ocean is a very big place and the historical measurement networks are plagued with sampling issues in space and time. Large scale, long term compilations globally (such as by Levitus et al, 2001; Willis et al, 2004) and regionally (i.e. North Atlantic) have indicated that the oceans have warmed in recent decades at pretty much the rate the models expected.
Since 2000, though, ARGO – which is a network of floats that move up and down in the ocean and follow the currents – has offered the potential to dramatically increase the sampling density in the ocean and provide, pretty much for the first time, continuous, well spaced data from the least visited, but important parts of the world (such as the Southern Oceans). Data on ocean heat content from these floats had been therefore eagerly anticipated.
Initial ARGO measurements were incorporated into the Willis et al, 2004 analysis, but as the ARGO data started to dominate the data sources from around 2003, Lyman et al reported that the ocean seemed to be cooling. These were only short term changes, and while few would confuse one or two anomalous years with a long term trend, they were a little surprising, even if they didn’t change the long term picture very much.
The news this week though is that all of that ‘cooling’ was actually due to combination of a faulty pressure reading on a subset of the floats and a switch between differently-biased observing systems (Update: slight change in wording to better reflect the paper). The pressure error meant that the temperatures were being associated with a point higher in the ocean column than they should have been, and this (given that the ocean cools with depth) introduced a spurious cooling trend when compared to earlier data. This error may be fixable in some cases, but for the time being the suspect data has simply been removed from the analysis. The new results don’t show any cooling at all.
Are we done then? Unfortunately no. Because of the paucity of measurements, assessments of ocean heat content need to use a wide variety of sensors, each with their own quirks and problems. Combined with switches in data sources over the years, there is a significant potential for non-climatic trends to creep in. In particular, the eXpendable BathyThermographs (XBTs – sensors that are essentially just thrown off the side of the ship) have a known problem in that they didn’t fall as quickly as they were originally assumed to. This gives a warm bias (see this summary from Ingleby and Palmer or the paper by Gouretski and Koltermann) , particularly in data from the 1970s before corrections were fully implemented. We are still going to have to wait for the ‘definitive’ ocean heat content numbers, however, it is important to note that all analyses give long term increases in ocean heat content – particularly in the 1990s – whether they include the good ARGO data or exclude the XBTs or not).
There are a number of wider lessons here:
- New papers need to stand the test of time before they are uncritically accepted.
- The ARGO float data are available in near real-time, and while that is very useful, any such data stream is always preliminary.
- The actual problem with these data was completely unknowable when Lyman et al wrote their paper. This is in fact very common given the number of steps required to create global data sets. Whether it’s an adjustment of the orbit of a satellite, a mis-calibration of a sensor, an unrecorded shift in station location, a corruption of the data logger or a human error, these problems often only get fixed after a lot of work.
- Anomalous results are often the driver of fundamental shifts in scientific thinking. However, most anomalous results end up being resolved much more straightforwardly (as in the case, or the MSU satellite issue a couple of years back).
Scientists working in a field build up a certain intuition about how things ‘work’. This intuition can come from a gut instinct, deep theoretical understanding, robust model results, long experience with observations etc. New results that fall outside of that framework often have a tough time getting accepted, but if they are solid and get subsequent support they will generally be incorporated. But that intuition is also very good at detecting results that just don’t fit. When that happens, scientists spend a lot of time thinking about what might be wrong – with the data, the analysis, the model or the interpretation. It generally pays to withhold judgment until that process is finished.
Thomas, your first word is “clearly” — so you appear to be reading from a study you can cite for us that supports your statement. What is your source? How old is it?
When I look, I find recent references to small changes from astronomical variation, which require amplification to change the climate. The recent science is focusing on finding out what provided the amplification. For example:
http://journals.hil.unb.ca/index.php/GC/article/view/1241/1621
“positive feedbacks to small changes in climate induced by Milankovitch changes in radiative forcing.”
Another example: http://www.aos.princeton.edu/WWWPUBLIC/alexey/publications/philander.fedorov.ice.aug8.pdf
“Although the Milankovich variations in sunlight are only on the order of 10% in high latitudes, they are now capable of inducing dramatic global climate changes associated with recurrent Ice Ages.
Apparently the drifting of continents altered conditions on land, and in the atmosphere and oceans in such a manner as to introduce processes capable of amplifying and changing the response to Milankovich forcing. …. This paper explores entirely different feedbacks involving interactions
between the ocean and atmosphere in low latitudes.”
And, this has all rather been gone over just recently:
https://www.realclimate.org/index.php/archives/2007/02/what-triggers-ice-ages/
[[Effect of southern hemispheric perihelion-solstice approach is gradual global oceanic warming with corresponding adjustment of current and air flows, oceanic thermal expansion with gradual shift in oceanic-atmospheric CO2 balance (with more CO2 being released on top of anthropogenic addition), ]]
At the moment the oceans are a net sink for carbon dioxide, not a net source of it. The oceans lose about 90 petagrams of carbon per year, but take in 92.
[[But what I dispute is the conclusion that CO2 is the main causal of this current warming phase, on the basis of the reality of the MIS-11 Interglacial when CO2 was quite normal, but sea levels were much higher due to extensive deglaciation well beyond what has occured so far, or projected to occur by the IPCC. ]]
Nobody ever said CO2 was the only thing that affected climate. Climatologists are well aware of the course of the ice ages. It has been a major focus of climatological study since the 19th century.
If you study the carbonate-silicate cycle which keeps Earth habitable, you will find that during a glaciation, weathering decreases, and so volcanic and metamorphic CO2 build up in the air. It takes a while for the high CO2 level to melt the ice again. So if you merely sample the period well into a deglaciation, you may find an ice age coexisting with high CO2 levels. You have to look at the whole process.
CO2 is a greenhouse gas. Adding more to the atmosphere heats the ground. That’s physics, not climate correlation.
Am I wrong in this statement?
Temperature can increase for 800 years regardless of CO2, the later rising of CO2 does not further increase temperature ( possibly only keeping temperature stable).
So in this particular case, CO2 levels are NOT responsible for Global warming?
Right?
Wrong?
Don’t know?
Marian
As just another reader here, I’d say all three statements look wrong to me.
I’d suggest you read some of the links here — and that you discount most everything other websites say you’ll find on RealClimate. Go to the source, use the search box at the top of the page.
You can look that up; much of the 2nd and 3rd hand stuff is bogus in a variety of ways (misrepresentation, oversimplification, flat out wrong).
When you read the RC articles, look for the text in _green_ from the climatologist Contributors, not the text in black, which is from all the rest of us kibitzers hanging around, some trying to make sense of it all.
http://www.google.com/search?q=%2Brealclimate+%2B%22800+years%22
Text in black (wry grin); my opinion of the three statements you propose:
Temperature isn’t going to increase for 800 years without anything else happening, anything else that happens is likely going to affect CO2 with life as it is on this planet nowadays.
There’s nothing magic about ‘800 years later’ — look at the ‘ice age’ threads.
Nothing is 100% responsible; many forcings combine.
As I recall, at present, it looks like in the absence of human activity the planet would have been slowly cooling from the peak temperature about 11,000 years ago. That’s s-l-o-w-l-y as in very, very slow. In that sense human activity may be responsible for more than 100%; offsetting cooling to zero and pushing climate the other direction. But that’s only looking at each previous ice age with the exception of the PETM event, the one most similar (albeit much slower) than the current human CO2 increase.
Re: #155 (Marian)
Temperature can increase for a lot of reasons.
Deglaciation begins because changes in earth’s orbital configuration redistribute incoming solar energy, so that more of it hits the polar regions, less the equatorial regions. This brings the heat to the ice, and starts wasting away the ice sheets.
Wasting away the ice sheets reduces the overall reflectivity of the planet (ice is highly reflective, land and open ocean are not). This causes more of the incoming solar energy to be absorbed rather than reflected back to space, and that warms the planet as a whole.
Warming causes the oceans to hold less CO2, which they release to the atmosphere. So at first, it’s temperature that causes CO2 change.
False. CO2 does absorb longwave radiation — the “greenhouse effect.” This does warm the climate. So after the initial “temperature causes CO2 change” event, the CO2 causes further warming. It’s important to realize that both factors are both cause and effect.
What we have is “warming causes CO2 increase causes further warming…” — a classic feedback mechanism.
One of the dangers of modern global warming, is that warming will further increase CO2 (and other greenhouse gases); the feedback works both ways.
Marian, Actually, if you look at the Vostok Ice Core data, there is clearly a spike in temperature after the CO2 spike starts, and the temperature starts to fall after the CO2 fall starts. So it looks like the CO2 exacerbates and maintains the warming epoch.
[[Am I wrong in this statement?
Temperature can increase for 800 years regardless of CO2, the later rising of CO2 does not further increase temperature ( possibly only keeping temperature stable). ]]
Yes, the statement is wrong. Increased CO2 does increase the temperature further. It’s a greenhouse gas.
Steve R. # 142, well, your hypothesis might qualify as a hypothesis, but not as a scientific hypothesis. First, what would be your basis for choosing 1 degree rather than 3? Second, your putative mechanism might be physically plausible, but there’s no evidence to suggest it’s acutally operating. On the other hand, we know CO2 is increasing. We know CO2 is a ghg. We know the added forcing due to the added CO2 is adequate to account for observed effects. What I don’t understand is the motivation for rejecting a theory that matches results very well in favor of vague ideas that aren’t even worked out. The physical world doesn’t much care whether we like the physics or not.
Re. #130 (Ray Ladbury) – What are other mechanisms?
I think that boiling down Milankovitch/Astronomical forcing to July 65N insolation curve is a gross oversimplification of the overall process, which is regional (large-scale) vs. global in nature. As with our annual seasons, the long-term changes in insolation are most pronounced at the polar regions and higher altitudes in both hemispheres, and this reaches a maximum at the intersection of perihelion and solstices, roughly every 10,000 years, a zone that we are currently approaching.
Likewise, boiling down the effect of the resultant increased/decreased regional insolation to +/- energy, is also greatly oversimplified. Albedo modulation is particularly critical, including that due to large changes in cloud cover, as well as major changes in the biosphere. If Svensmark is correct in his hypothesis that cloud cover is modulated by cosmic ray flux, which is in turn modulated by solar wind, then that could become a major factor in the equation, since astronomical orbital variation would in effect drive large-scale regional cloud cover and resultant albedo variation. The results of CLOUD at CERN should provide more insight on that.
With respect to biosphere changes, the best proxies are those found in previous interglacials, particularly MIS-11, which it why it is critical to understand exactly what happened then.
Re. #131 (Tamino) – Greenland vs. North Atlantic
There are several other locations with good YD termination proxies. The fact that the temperature change was that high in Greenland actually supports the notion that the effect is most pronounced at the poles and higher latitudes, does it not?
Re. #136 (Hank Roberts) – MIS-11 Sea Levels
Thanks for the references. Yes, decoupling eustatic sea level rise from uplift is quite difficult, particularly that far back. But irrespective of that, there is now general agreement, including from the IPCC, that Eemian sea levels were higher by ~5m, and those are generally the basis for estimating the MIS-11 sea levels. Given the increased length of that interglacial, which is no longer disputed, and the faunal fossil evidence for this period in northern latitude, one can argue that it was probably higher than the Eemian, but I agree that much more research is required on this critical point.
#138 (Thomas Lee Elifrtiz) – Higher CO2 ppm will melt all of the ice.
A recent paper in Nature – Continental Ice in Greenland during the Eocene and Oligocene, Eldrettt, etal. 2007 – suggests that there was glaciation during periods when CO2 levels were well above today, perhaps even higher than 1000 ppm. While I don’t dispute the Greenhouse Effect, the degree to which it directly impacts atmospheric temperature at different concentration levels is perhaps more debatable. Likewise, the optimal global temperature distribution to stimulate glaciation or glacial melting, i.e. changes in mass balance, is also perhaps debatable.
#143 (Blair Dowden) Precession does not affect insolation.
While you are right that global insolation is the same, the real climate issue is what the insolation distribution is on a large-scale regional basis, and this is in turn affected by the envelope of precession – the degree to which eccentricity places the orbit closer or farther away from the sun at perihelion and aphelion. Changes in axial tilt, and changes in orbital plane inclination I might add, also affect the degree to which the polar regions face more directly into or away from the sun at the solstices, with climatic implications. We are currently in a summer southern hemisphere forcing configuration and therefore the notion that this can be analyzed via July 65N insolation curve appears to be the root of the problem.
#154 (Barton Paul Levinson) – CO2 heats the ground
I don’t dispute the fact that GHG trap heat. But there is also a long chain of inorganic and organic processes/feedbacks that take place once CO2 is in the atmosphere, or in the ocean, many of which we are just beginning to understand.
re 155.
[So in this particular case, CO2 levels are NOT responsible for Global warming?]
Here is the real climate moderators response to your question from the listed thread:
https://www.realclimate.org/index.php?p=13
“In other words, CO2 does not initiate the warmings, but acts as an amplifier once they are underway. From model estimates, CO2 (along with other greenhouse gases CH4 and N2O) causes about half of the full glacial-to-interglacial warming.
Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a “feedback”, much like the feedback that results from putting a microphone too near to a loudspeaker.”
Although the Milankovich variations in sunlight are only on the order of 10% in high latitudes
ONLY 10%. I rest my case. Heaven forbid if there were 100% changes in solar insolation. You guys need to start looking for another planet. That requires that you start looking AT other planets.
Dan, the main problem with Svensmark’s ideas are that his cause happens to be absent–that is, GCR fluxes are not changing. Moreover, there is no real evidence that cloud cover is changing significantly–that ought to be easy to document from weather reports. Finally, the fact the Svensmark shows a rough correlation of cloud cover to the 11 year solar cycle is not significant in the absence of a statistical measure of that variation, and even then, it is not necessarily causal–a lot of things correlate to the 11-year cycle. Moreover, don’t forget that clouds can warm as well as cool. As any amateur astronomer knows, the best nights for star gazing are often the coldest.
Likewise, it doesn’t matter how you package it, dice it, slice it or mangle it, insolation by itself is not adequate to explain the level of warming seen. It requires an amplification, and you have not proposed anything credible. CO2 is a working theory that explains the results–why are you anxious to discard it? Of course if you do come up with a credible mechanism, it will be very exciting, because it would mean that we would have to understand why CO2 was suddenly not acting like a greenhouse gas. I don’t think that is very likely, though.
Re #s 142/160: “Actual climate sensitivity to CO2 is 1.0C (GHG positive feedbacks are effectively canceled by negative feedback from clouds), not the 3C calculated mostly from insolation changes (including volcanic solar dimming).”
What Steve R. suggests is essentially the same as Lindzen’s discredited “iris effect.” If it was correct, there would be evidence of it now (in the form of an increase in clouds to counteract the recent warming). That evidence has been looked for and found to not be there. It also fails to explain the PETM. Underlying the “iris effect” and similar arguments seems to be the idea that our present climate (Pleistocene glacial cycles) is inherently stable. What paleohistory shows is quite the reverse. The present climate epoch is 1) very recent as these things go (just the last 3 million years or so) and 2) a cold extreme that is very unusual relative to the climate history of the last half-billion years. For more than 80% of that period there weren’t even permanent ice caps. Also, the glacial cycles don’t even have internal stability — about 700,000 years ago, some very subtle change (meaning not at all obvious in the geologic record) shifted the length of the cycles from about 40,000 years to about 100,000 years. Given this and the association between CO2 levels and temperature before and during the course of the glacial cycles, it seems very obvious that a seemingly small push from anthropogenic CO2 could result in a rather drastic climate shift.
Dan Fregeau is trying to claim that fossil fuel-sourced CO2 and anthropogenically-sourced CH4 and N2O increases in the atmosphere aren’t causing the oceans to warm, based on the fact that sea levels were once higher than they are now when CO2 levels were lower.
Timescales, Dan, timescales. We are currently increasing CO2 at rates ~30X greater than anything observed in the ice core records. A slow transition from a glacial period to an interglacial over six thousand years is a bit different from a transition from an interglacial period to some unknown future state due to rapid increases in the greenhouse effect over the course of a single century.
The response time of ocean warming to anthropogenic increases in the greenhouse effect is slow due to the thermal inertia of the oceans – but that also means that the oceans will continue to warm for centuries even if CO2 levels are stabilized at the current ~380 ppm. The Titanic analogy fits; the ship was too big and moving too fast to respond to the rudder in time.
The fact that atmospheric CO2 continues to increase at an accelerating rate (1.4 ppm/yr over 1960-2005; to 1.9 ppm/yr over 1990-2005, to ?) could be attributed to several things: an increase in the rate of fossil fuel CO2 production as well as a decrease in the ability of the biosphere and oceans to absorb CO2. Theroretical arguments indicate that the biosphere and the oceans will actually release CO2 to the atmosphere as the oceans warm and as the biosphere becomes more stressed; at the very least they will not be able to absorb fossil CO2 at the current rate, and this might already be happening.
Re #161: Dan, you provided no link for the Eldrett paper, but I had a look at the abstract. It concludes “our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented, at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.” You kind of didn’t mention the bit about temperatures being *substantially* higher. Also, note that isolated glaciers do not a continental ice sheet make. This paper does not support your argument.
>> “Although the Milankovich variations in sunlight are only on
>> the order of 10% in high latitudes…”
>
> ONLY 10%. I rest my case.
Could you be persuaded to show your reference, or your work if you’re doing this calculation yourself? You’re asserting the opposite of the published science, starting from the same facts.
Rest assured many of us believe there are good reasons to get our descendants off this one planet. You don’t need to believe the climatologists are wrong about insolation and climate.
Do we need a reason to hurry to get humanity spread out more broadly?
I’d say the precautionary principle suffices: there may be a truly scary explanation for the Fermi Paradox! We’ve advertised the bullseye we live on; we should send some of the grandchildren elsewhere as soon as possible. Just, you know, in case it’s a wise precaution.
Let’s see . Temperatures rise, and 800 years later CO2 levels rise. Both temperatures and CO2 then continue to rise.
Can somebody explain how that proves causation??
Tom, how much physics have you had? You understand what science does, and how it differs from “proof” in math?
Do you know how solubility changes with temperature (the common example is, run cold tap water into a glass; let it warm to room temperature; notice the bubbles coming out).
Have you read Arrhenius’s basic work, and the followups?
Assuming you’re asking a serious question, it’d help if you’d give some idea what you know now, as a place to start answering you.
Re #166, I am still trying to figure out how measurements of CO2 (or temperature proxies) taken from ice cores hundreds or thousands of years apart can be said to be 30x lower than the present rises in CO2. Is it physically impossible for CO2 to fluctuate naturally at today’s rate? Ice core measurements that span centuries could easily hide such fluctuations.
Eric, there is better information available than you are looking at. You seem to be making the mistake Lindzen makes in public. For example:
“… Greenland cores (GRIP, GISP2) and Antarctic cores (EPICA DML) have sub-annual resolution in many cases for the isotope (temperature) records, and at least decadal resolution (Law Dome, Siple Dome) for the greenhouse gases (CO2, CH4). It’s true that the very longest records (Vostok and Dome-C) have coarser resolution ….”
https://www.realclimate.org/index.php/archives/2007/02/quick-pre-spm-round-up/
[[Is it physically impossible for CO2 to fluctuate naturally at today’s rate? Ice core measurements that span centuries could easily hide such fluctuations.]]
Could be, Eric. Although absence of evidence for a phenomenon hardly proves the presence of that phenomenon. But in the case of the present warming, the radioisotope signature of the new CO2 shows that it’s coming largely from fossil-fuel burning. So speculating about its coming from a natural source is out of court from the beginning. You’re explaining something that doesn’t need to be explained.
Re 169, 171
Why don’t you start by taking the time to read the peer-reviewed literature cited in the IPCC reports?
You are spending a lot of time trying to pick holes in the conclusions of mainstream climatology, with the result that your ignorance of the science quite evident. Do you spend as much time and energy picking hole in the skeptics “alternative theories,” such as they are?
Re 160: Ray>well, your hypothesis might qualify as a hypothesis, but not as a scientific hypothesis.
What is unscientific about it? It is testable given good quality data.
Ray> First, what would be your basis for choosing 1 degree rather than 3?
Clarity of discussion. The same argument can be made about almost any number between 0 and 3.
Ray> Second, your putative mechanism might be physically plausible, but there’s no evidence to suggest it’s acutally operating.
There is some evidence (non-conclusive) in the referenced info.
Ray> On the other hand, we know CO2 is increasing. We know CO2 is a ghg. We know the added forcing due to the added CO2 is adequate to account for observed effects.
While we have considerable evidence that feedback effects could imply a 3C sensitivity, that depends on feedback from ghg forcing being the same as from insolation forcing. Do we know that is the case? They clearly have a very different distribution of warming effects.
Ray> What I don’t understand is the motivation for rejecting a theory that matches results very well in favor of vague ideas that aren’t even worked out.
My motivation is understanding reality and avoiding making important decisions on a mis-understanding of reality. I am not rejecting the standard theory, just looking to see if there are alternatives. After all, epicycles also fit the data at one time.
Ray> The physical world doesn’t much care whether we like the physics or not.
I agree. So why be afraid of looking closely at all possibilities?
165:Steve Bloom >…there would be evidence of it now (in the form of an increase in clouds to counteract the recent warming). That evidence has been looked for and found to not be there.
I am interested in seeing that data. Can you provide a reference?
Could you be persuaded to show your reference, or your work if you’re doing this calculation yourself? You’re asserting the opposite of the published science, starting from the same facts.
I’m not disagreeing with you or published science, I just find it amusing that someone would find a 10 percent variation of solar insolation at 65 degrees latitude, a variation which demonstrably paces the ice ages, to be ‘small’, as in trivial. My audio signal is also a very tiny voltage, but it amplifies to high fidelity and high power just fine. The ice and ocean cores yield very high fidelity signals in the paleoclimate record, and that’s so weird, because those isotopes, and diatoms and foraminifera are so darn tiny, it’s no wonder nobody but scientists can take them seriously. I’m pulling your chains here.
This is what I think is happening, a brief glance at the record makes it fairly obvious. As natural background carbon dioxide slowly settled below a critical threshold of around 300 ppm or so, who knows why, but clearly Earth’s biosphere is slowly winding down, geological processes have become relatively stabilized, whatever the case, with the continental distributions being what they are, the climate begins to oscillate, triggered by orbital variations. Are you with me? I’m simplifying this a great deal. Milankovitch forcing theory as THE PRIMARY TRIGGER, the gate signal if you will, has withstood the test of time, no matter what geological and climatic circumstances are amplifying it and altering it. Get over it.
You can go ahead and try and refute it, but it doesn’t matter one whit what the comparative signal levels are, the climatic oscillations demonstrably exist, the oscillating signal is clearly being amplified, and the paleoclimate records verify that every which way but naught. If you’ve got a better theory, I will patiently await reading your peer reviewed publication.
So the initial claim to have a hard time understanding how a weak signal can be amplified, was just too amusing for me to pass by. Sorry for the misunderstanding.
What we have here is a climatic oscillator and amplifier that is just about on the verge of shorting out and going up in smoke. So get your tools together, Dr. Spock, this is going to take some work. Edith Keeler must die.
Thanks Hank, from what I can see in the links, the annual layers are good to about 11k years and there’s some close approximation to that for “tens of thousands” of years before that. But they don’t talk about the sources of smoothing and the number of years of data that would be incorporated (by diffusion mostly) into one measurement. Barton, the radioisotope argument is good evidence for the current CO2, but doesn’t preclude natural fluctuations whatsoever. The lack of evidence from prehistorical ice cores doesn’t imply lack of CO2 fluctuations, only the inability to measure them. Other proxies can provide that evidence, or physical models that preclude any realistic chance of rapid CO2 fluctuations. I believe there is work in the former, the latter is probably still too difficult.
Re 161; “If Svensmark is correct in his hypothesis that cloud cover is modulated by cosmic ray flux, which is in turn modulated by solar wind, then that could become a major factor in the equation, since astronomical orbital variation would in effect drive large-scale regional cloud cover and resultant albedo variation.”
Dan, what are you trying to say here? Surely not that astronomical orbital variation affects the solar wind.
[[Barton, the radioisotope argument is good evidence for the current CO2, but doesn’t preclude natural fluctuations whatsoever.]]
Nor does it preclude the existence of leprechauns. Why are you advancing a theory for which there is zero evidence? And if “the radioisotope argument is good evidence for the current CO2,” what is the point of arguing that natural fluctuations are possible? Possible or not, they’re not happening now. I can’t understand what you’re trying to achieve here.
Re: #178 (Eric)
On the contrary, the lack of CO2 fluctuations in ice cores, even at grainy resolution, is strong evidence (but not proof) of the lack of fluctuations in the physical system.
Grainy resolution means we’re unlikely to detect a single fluctuation. But if there are many fluctuations, and we have thousands of measurements, then the probability we’ll fail to catch any of them is very small.
Furthermore, there are plausible (albeit unlikely) physical processes that can dramatically increase atmospheric CO2 on very short timescales. But I know of no physical process that can dramatically decrease atmospheric CO2 on very short timescales. That’s one of the dangers of CO2: even when removed by natural processes, it tends to stay in the atmosphere for a very long time.
So, on statistical and on physical grounds, it’s overwhelmingly unlikely that we’ve “missed” large-scale fluctuations due to low time resolution of ice core data.
Ray: re. 30 [The models and paleoclimate data are the only handles we have on the potential effects of climate change–]
I’d like to niggle with you and say that physics is a third way to help indicate what climate change might have in store for us.
With physics, you can calculate the energy inbalance that we humans are causing by adding CO2 into the atmosphere and test against model results and paleoclimate data.
This is just a niggle, but it helps the public understand that this is not “handwaving”.
https://www.realclimate.org/index.php/archives/2005/02/why-looking-for-global-warming-in-the-oceans-is-a-good-idea/
This comment from 166: “We are currently increasing CO2 at rates ~30X greater
than anything observed in the ice core records.” The ice core records can’t be compared to today’s fluctuations due to resolution problems. Similar fluctuations could have occured with isotope ratios as well with similar measurement problems. I realize this isn’t much evidence (i.e. a physical process explanation), but the measurements in this paper http://www.holivar2006.org/abstracts/pdf/T3-032.pdf suggest that isotope ratios rose well before the industrial revolution (and well before the significant emissions: http://cdiac.ornl.gov/ftp/ndp030/global.1751_2003.ems)
[Response: There is no support for such a statement in the linked poster. The ice core records show a sharper decrease in d13C because the mixing time is relatively short and thus the trend from ~1750 on is very clear. In ocean sediment, bioturbation (mixing of the sediment by bottom dwelling beasties) will cause more significant smoothing. Given those constraints, the match between the ocean d13C and the ice core d13C is impressive, not contradictory. – gavin]
Tamino, I don’t think that it is physically possible to randomly capture a CO2 spike in the ice core measurements since the measurements are smoothed from centuries (in the 100k and older cores) of actual CO2 values. A smallish spike of CO2 would reduce to 40% in 50 years (see figure 4 in http://isam.atmos.uiuc.edu/atuljain/publications/WuebblesEtAl.pdf) but how that impulse response scales to larger spikes is uncertain due to a large amount of nonlinearity in the carbon cycle. Obviously there would still need to be a physical explanation for a “spike” in the first place.
Re #166, “The Titanic analogy fits; the ship was too big and moving too fast to respond to the rudder in time.”
The Titanic analogy fits in many other ways, as well. (I saw the movie again recently.) The lookout crew didn’t have binoculars bec the rich had taken all of them, but were partying inside — similar to the gov trying to silence the scientists, then fiddling while the world burns. They didn’t have enough lifeboats bec the rich wanted more room on deck without those ugly ?wind generators? and bec of arrogance that the ship couldn’t sink (the denialist stance). The poor were left to last, most to die, while a few rich escaped in life boats; the poor of the world, who contribute least to GW, will disproportionately suffer GW harms.
The movie theme was about arrogance, wealth, & selfishness v. good human values, including love and sacrifice.
Eric, let’s say you continue to ignore the high resolution ice cores and focus solely on the low-resolution ones. How about looking at the sediment cores, then? Just one example, as a way to search. What puzzles me is you’re arguing your opinion but haven’t documented any publication that supports it.
So look at a different source for higher resolution info, sediments instead of ice; you know diatoms build their shells out of dissolved CO2, you know there’s a level coming by 2100 at which that process stops because the shells dissolve; that’s happened before, though the species change dramatically over time so you have to really focus on the details to know what’s a good indicator.
But the layers are quite precise and shells aren’t going to go migrating after they’re laid down in an annual layer.
http://www.journals.royalsoc.ac.uk/(b1ot4izzfj1qg3vjcld0xifx)/app/home/contribution.asp?referrer=parent&backto=issue,3,14;journal,47,153;linkingpublicationresults,1:102021,1
Wups, Gavin already covered that in his comment about the poster study a few back, I missed it. So, good for you, you’re getting the data and an explanation for it.
‘Bioturbation’ is bottom dwelling worms and clams and whatever else stirs up the surface layers; it’s understood (we know what animals did what to the bottom) and can be tested against known specific layers from say volcanic eruptions — how much does that layer get spread through the mud by the animal life, that’s a good way to estimate how accurate the rest of the layers are).
Re #176: Steve R., search this blog for “ISCCP” and “iris” (separately).
Re #184: And explanations for why they were all too small to leave any trace, why they don’t show up in the more finely-gradated recent record, and why they don’t seem to have happened during the present interglacial. Eric, I’m afraid it’s starting to sound like “low sensitivity in the gaps.”
Re #157: tamino, you said
This is not how I understand it.
The net annual insolation at any latitude (not just 65N) does not change much. So while under certain condition the high latitudes can get up to 80 W/m2 extra insolation (a lot more than 10%), six months later the Earth will be on the other side of the sun, and the same region will get 80 W/m2 less. Correct me if I am wrong, but I don’t think there is any redistribution of incoming insolation between polar regions and the equator.
I also think that Dan Fregeau in #161 is wrong about the effect of eccentricity. Today at summer solstice the southern hemisphere does receive more insolation because the Earth is closer to the sun at that time. But in the southern winter the Earth is further away, so the winter is relatively colder. The energy gained in summer is lost in winter.
The only difference the orbital cycles make is the timing of seasonal warming and cooling, not the net amount. Locally as well as globally. This paper in Science shows the large seasonal variations in insolation in the polar regions.
Steve Bloom >…search this blog for “ISCCP” and “iris” (separately).
I tried that, saw lots of discussion about clouds, but nothing that looked like reliable data showing no change in cloud cover.
Re: Comment 164 (Ray Ladbury) “the main problem with Svensmark’s ideas are that his cause happens to be absent–that is, GCR fluxes are not changing.”
Ray, there is evidence that the GCR changed in the 20 th century.
http://hesperia.gsfc.nasa.gov/sspvse…ntergreen1.pdf
Quote from the above link.
In The Modern Era (Since 1954)
( 1 ) The galactic cosmic ray intensity near earth has been one of the lowest in the past 1150 years.
( 2 ) The frequency of occurrence of large solar particle events has been low compared to the long term average.
For A Period Similar To 1889 – 1901
( 3 ) The galactic cosmic ray intensity was higher compared to the modern era by factors of:
– 7.0 AT 100 MeV
– 3.5 AT 300 MeV
– 2.25 AT 1.0 GeV.
Re #189: Blair, the key is that summer melt then exceeds winter accumulation. Note that there’s nothing about colder winters that tends to increase accumulation.
Re: #189 (Blair Dowden)
It’s true that the primary ice-melting mechanism appears to be the change in the seasonal distribution of insolation. But it’s not correct that “The only difference the orbital cycles make is the timing of seasonal warming and cooling.”
The precession cycle has no effect on annual average insolation at any location. But the obliquity cycle does; a change in obliquity from 22 deg. to 24.5 deg. increases annual average insolation at latitude 65 deg. by 5 W/m^2, and at the pole by 17 W/m^2, while insolation at the equator decreases by about 3.5 W/m^2.
Re: #191 (William Astley)
The link you gave doesn’t work.
Reply to Comment 164 (Ray Ladbury) “Moreover, there is no real evidence that cloud cover is changing significantly–that ought to be easy to document from weather reports… Moreover, don’t forget that clouds can warm as well as cool. As any amateur astronomer knows, the best nights for star gazing are often the coldest.”
Overall, clouds reflect more solar radiation than they trap, leading to a net cooling of ~27.7 W/m2 from the mean global cloud cover of ~63.3% [Hartmann, 1993].
According to Tinsley and Yu’s paper (see link below), an increase in GCR results in an increase in low level clouds and a decrease in high level clouds. There are papers that ostensibly provide some support for a link between GCR and low level clouds, however, the papers in question are disputed by others. (See Palle, satellite data and earthshine data.)
Svensmark’s satellite data and analysis was disputed as others thought satellite data could not show whether the clouds were low or high and disputed detailed aspects of Svenmark’s analysis. Palle used a different analytical technique than Svensmark, which Palle thought resolved some of the analytical issues. I did not find any papers disputing Palle’s earthshine data and analysis, however, there probably were some.
Atmospheric Ionization and Clouds as Links between Solar Activity and Climate
By Brian Tinsley and Fangqun Yu
http://www.utdallas.edu/physics/pdf/Atmos_060302.pdf
The solar cycle appears, based on the data I have seen, to be moving towards a sever minimum. If Tinsely and Yu’s theory is correct and Palle’s back of the envelope estimate of the forcing is correct there should be a cooling of around 5 W/m^2, over the next four years. (Solar large scale magnetic field takes about four years to dissipate if the solar cycle is interrupted.)
There is no need to speculate, however, if the change is significant there will be a need to relook at the fundamentals. If not, then the issue should be resolved.
Comment:
The data did not support T & Y’s, theorized reduction in high level clouds with increasing GCR. Maybe the theorized high cloud mechanism requires higher energy GCR. According to T & Y low level clouds result in net cooling and high level clouds net warming. Mid level clouds about neutral. See their paper for details.
Re #190: Steve R., see this discussion. Per Gavin the ISCCP team think these papers are correct (that the long-term cloud trends are more or less flat). This RC post is also somewhat relevant.
Re #193: Thank you, tamino, for correcting my misconception that obliquity does not affect the distribution of insolation. But I did get it right that the position in the precession cycle referred to by Dan Fregeau does not change the amount of insolation received in any region, and will not affect sea surface temperature in the way he claims.
Gavin and Hank (#186,#187), thanks, the biological proxies are worth more studying. My thoughts might have been backwards, the isotope ratio in forminifera may be related to CO2 concentration rather than solely to CO2 source (anthropogenic or natural methane) although this is apparantly controversial (see http://www.shef.ac.uk/aps/apsrtp/humphreys-claire/masters-dissertation.pdf p. 4). Also for Steve B (#188), it’s not so much “gaps” as comparing 1000’s of data points in the current interglacial to about two dozen in the previous interglacial to maybe 3-5 in the ones prior to the previous one (ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/vostok/co2nat.txt)
Agree with the removal of bias from the float data as the NOAA paper outlines. Not sure the bias was real bias or actual areal temperature anomalies, my random continous sampling of inflight air temperatures and pressures at various levels indicates pools of instability outside of the normal range. I have a suspicious that there was a cooling for the period as there does not seem to be an acknowledgment of the inflows of melt water into the ocean circulatory systems, cold water can be quite diffuse. If there is a suppressing northern and southern melt water temperature effect then the proof will be rising but behind the model temperature increase estimates over the next decadal period.
I note that when people talk about CO2 levels in the distant past to today they compare the CO2 in the ice to the atmospheric levels of today. When I have looked at the Ice core record there is a difference between the age of the ice and the air trapped within. My question, are there any ice core records that can be compared to the atmospheric record of CO2 since the late 1950’s. My concern is that without actually being able to compare known atmospheric CO2 trends to trapped CO2 in ice, any information obtained about past CO2 levels may be dubious at best.