Omega Centauri says:
10 Jul 2015 at 9:10 PM
Aaron. Beyond a depth of a couple of tens of meters, ice is self healing, i.e. the hydrostatic pressure (the weight of all ice above a given spot per unit area) is greater than the resistance to plastic flow. So cracks cannot stay open, they will be pushed shut by the pressure….
#90-2: Dunno ’bout the actual science, but the abstracts says this:
“Zharkova and her colleagues derived their model using a technique called ‘principal component analysis’ of the magnetic field observations from the Wilcox Solar Observatory in California.”
So you’d have to think denialati will rush to denounce it–they’re all apparently convinced that PCA is just a recipe for hockey sticks. ;-)
Here’s one that might be a useful model — it’s “property values by county” but something similar, once we have the ability to map by county, would be interesting for climate-related changes.
Applying the approach to, say, planting/growing zones could be interesting now.
Aaron, the total heat available from surface meltwater is just its volume times the heat of fusion of water, and this assumes all the water is refrozen. Gravitational energy is much smaller than this sum.
It we are talking about heating the bulk of the ice, and not localized smaller volumes it would take a rather large amount of surface melting to make much of a dent in the “coldness” of the ice. By “coldness” here I mean how far below the pressure melting point the ice is at. I think for Greenland this is something like -30C to -50C, so a unit volume of meltwater can bring a few times its volume of ice up to the melting point -if it all refreezes at depth. Melting at the surface especially in the interior is going to be well under a meter per year, so the timescale for changing the ice from the dry to wet state should be several centuries or more.
Now, what is the fate of injected meltwater? Ultimately it either refreezes, in which case it serves as a heat source for the deep ice, or it flows out under the ice and makes it to the ocean (in which case its heat of fusion is not lost to the ice). I think the fact that fastflow episodes are a summer phenomena suggests the liquid water is lost fairly quickly, which if true is reassuring, since if it pooled from year to year basal sliding resistance could be lost.
siddsays
Re:cold content of Greenland
Box is an author on a paper with Fettweis from a couple years ago on erosion of the “cold content” of the ice, although he was looking at drops in albedo. More recently Enderlin, Howat wrote a paper indicating surface mass balance had begun to dominate mass waste. Estimating that SMB is about 200 GT gives an upper limit on heat flux into the cold reervoir, ? Comparable to the albedo effect i think, but i have not immediately the references to hand.
…. The active role of surface melt, i.e. external forcing, contrasts with previous views of glacier surges as purely internal dynamic instabilities. Given sustained climatic warming and rising significance of surface melt, we propose a potential impact of the hydro-thermodynamic feedback on the future stability of ice-sheet regions, namely at the presence of a cold-based marginal ice plug that restricts fast drainage of inland ice. The possibility of large-scale dynamic instabilities such as the partial disintegration of ice sheets is acknowledged but not quantified in global projections of sea-level rise.
Citation: Dunse, T., Schellenberger, T., Hagen, J. O., Kääb, A., Schuler, T. V., and Reijmer, C. H.: Glacier-surge mechanisms promoted by a hydro-thermodynamic feedback to summer melt, The Cryosphere, 9, 197-215, doi:10.5194/tc-9-197-2015, 2015.
> Hank: You asked for cites, so you should remember it.
Your 2002 post? if you can find it, a link would be useful. I tried.
Concerned Denizensays
I would like to hear any expert opinions on what I have recently read concerning the state of the jetstream over Siberia at the moment (i.e. that it has fractured/disintegrated in defiance of all models, and now just appears chaotic…)
Is this true?
Is it a new (and unheard of) occurrence?
IF true, what might it portend?
or will it most likely just fix itself and carry on regardless…?
0^0says
This being an open thread..
I see every now and then a graph on NASA servers being used as a “proof” that there has been some kind of change of view to greenhouse effect and planet’s energy balance at NASA
That is patently ridiculous claim but you see these.. (sigh)
I have not found any links from NASA to that particular file and thus cannot figure out the context of it.
My guess is that it has been part of energy balance presentation pages in 2012 or earlier and is a fragment that remains after other stuff had been removed in an update..
Any clue where the rest of this could be found, including how greenhouse effect gets linked to this presentation..?
@88…There is a pretty clear difference between clinical paranoia and the paranoia exhibited by internet conspiracy theorists.
Talk like this is what led to the original article being “controversial” as it made some sort of “diagnosis” about individuals. It clearly did not except in the minds of those intentionally spreading mis/disinformation.
It is wrongheaded to suggest that the typical internet conspiracy theorist is mentally ill. It simply is not the case. That is not to say they are not totally wrong.
This same phenomenon occurs in every intro to abnormal psych course where every student sees themselves having the same symptoms as those diagnosed with the various psych disorders they are reading about.
Thanks Gavin.. The link you provided has the latest full picture. The thing “they” seem to stress is that there is no “backradiation” nor imbalance in that older diagram so NASA must have second thoughts.. Well, you cannot convince conspiracy theorists with “interesting” views to physics fundamentals.. ;)
Dougsays
“OMG. Just look at all the official models for Arctic sea ice included in the IPCC report in 2007 (AR4), and look at what actually happened to the ice in that and succeeding years.
Revisionist history seems to be rampant among certain quarters, here.” -Mr. Wili
As has been pointed out to you a few times Wili, models did predict rapid collapse, and thus were not fringe as you claimed. Your refusal to acknowledge that you were wrong is disappointing.
You like to move goal posts in your responses. I am sure your heart is in the right place, but tend towards doomerism at the annoyance of many in my opinion.
re 103: Heat delivered into the ice does not have to melt it, only add enough heat to bring small volumes of ice close to their pressure melting point. Ice in these volumes will flow more rapidly, setting off fractures in their margins. Fracturing allows ice flow, and ice flow is work that can deliver large amounts of potential energy to small volumes of ice. Fractures in ice can concentrate the energy in the ice flow at the margins of the fractures to drive additional fracturing.
Outer ice acts as bulwarks supporting the central massif. Ultimately, the stress from the weight of the central massif puts a massive tension stress on the small volumes of the bulwarks structures, and they fracture.
Once the temperature of the ice rises to near its pressure melt point, the potential energy in the ice can fracture enough of the ice to produce a slurry. For the ice to fracture into a slurry that can flow on a 2% grade, only an infinitesimal amount of ice needs to melt.
Basic Parts of the Radiation Budget
Solar Incident Energy
Solar Reflected Energy
Earth Emitted Energy
Incoming solar radiation is absorbed by the Earth’s surface, water vapor, gases, and aerosols in the atmosphere. This incoming solar radiation is also reflected by the Earth’s surface, by clouds, and by the atmosphere. Energy that is absorbed is emitted by the Earth-atmosphere system as longwave radiation. The component diagram has additional details.
It says:
Curator: Jay Madigan
NASA Official: Lin Chambers
Last Updated: 11/15/2011 05:22:33
+ Contact S’COOL
Regrettably this page fails to meet the criterion attributed, apparently apocryphally, to Einstein: “Everything should be made as simple as possible, but not simpler.”
That’s hard to do, given that it’s a complex subject.
There’s a page aimed at teenagers that handles the basic information — greenhouse gases including water vapor are warmer than space or dry air.
http://mynasadata.larc.nasa.gov/804-2/1035-2/
but oddly (or not, as it’s a Forrest Mims page) it never explicitly says that the greenhouse gases, being warmer because they collected heat radiated from the surface, are radiating heat back toward the surface.
Perhaps that conclusion was left for the students?
AICsays
Yet another impact from rising CO2:
Gattuso et al: Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios
Science 3 July 2015:
Vol. 349 no. 6243
DOI: 10.1126/science.aac4722
Speaking of “data visualization” there’s a new blocok of text appearing next to the Recent Comments containing the words “Tweet” and “SUMOME” — it appears to be an email harvesting tool, maybe from WordPress, maybe a hitchhiker. Poked at it a bit:
The marked block contains “Tweet SUMOME” (Tweet in green and underlined to indicate it is a link, but “SUMOME” in faint gray smaller text, not underlined, although it also is a link. The word “SUMOME” links to some kind of optimizing web page that says:
“We’ve noticed many struggle to collect emails at all because the tools just aren’t available or are far too expensive. So we thought why not make them available so you can do the same?”
It offers to run Adobe Flash (persistently). Adblock doesn’t block it (yet) and NoScript doesn’t find it (yet).
I’m sure it’s only appearing there because it’s trying to serve us in a helpful way, to somebody; perhaps it’s a cookbook.
If energy from the Sun decreased only slightly, why did temperatures drop so severely in the Northern Hemisphere? Climate scientist Drew Shindell and colleagues at the NASA Goddard Institute for Space Studies tackled that question by combining temperature records gleaned from tree rings, ice cores, corals, and the few measurements recorded in the historical record, with an advanced computer model of the Earth’s climate. The group first calculated the amount of energy coming from the Sun during the Maunder Minimum and entered the information into a general circulation model. The model is a mathematical representation of the way various Earth systems—ocean surface temperatures, different layers of the atmosphere, energy reflected and absorbed from land, and so forth—interact to produce the climate.
When the model started with the decreased solar energy and returned temperatures that matched the paleoclimate record, Shindell and his colleagues knew that the model was showing how the Maunder Minimum could have caused the extreme drop in temperatures. The model showed that the drop in temperature was related to ozone in the stratosphere, the layer of the atmosphere that is between 10 and 50 kilometers from the Earth’s surface. Ozone is created when high-energy ultraviolet light from the Sun interacts with oxygen. During the Maunder Minimum, the Sun emitted less strong ultraviolet light, and so less ozone formed. The decrease in ozone affected planetary waves, the giant wiggles in the jet stream that we are used to seeing on television weather reports.
The change to the planetary waves kicked the North Atlantic Oscillation (NAO)—the balance between a permanent low-pressure system near Greenland and a permanent high-pressure system to its south—into a negative phase. When the NAO is negative, both pressure systems are relatively weak. Under these conditions, winter storms crossing the Atlantic generally head eastward toward Europe, which experiences a more severe winter. (When the NAO is positive, winter storms track farther north, making winters in Europe milder.) The model results, shown above, illustrate that the NAO was more negative on average during the Maunder Minimum, and Europe remained unusually cold. These results matched the paleoclimate record.
Why does deforestation and land use in general have a slight cooling effect? I would have thought the opposite would be true, with greater reflection of infra-red radiation.
siddsays
Re:”cold content” language
The phrase is not mine, take it up with Box et al. doi:10.5194/tc-6-821-2012
“In an example with realistic boundary conditions, the additional 148 EJ solar energy is sufficient to completely erode the “cold content” of the 1.494 × 106 km^2 accumulation area to a depth of 14 cm, assuming its temperature, density, and specific heat to be −10C, 360 kg/m^3, and 2110 J/(kg K) respectively.”
On the other matter, it’s probably not worth dignifying the whiners with a response, but can we just point out that “fringe” does not mean non-existent. That there was a study 2006 and that its estimates were well outside of all those included in the ’07 IPCC report makes it by definition, ‘fringe.’ “Fringe,” after all, does not mean “non-existent”!
I concede that I was unaware of the study, and thank our uber-cyber-sleuth hank for ferreting it out. But its existence confirms rather than detracts from my general point…the report was clearly on the ‘fringe’ of all the reports included in the international report that most everyone looks to for the definition of the mainstream view on these things.
It was on the ‘fringe,’ and it was right (well, more accurate than all the other, more ‘main stream’ model included in the IPCC.) Do I really have to argue here that science is not determined by what is or is not ‘on the fringe’ of current thinking at any particular moment, but by what gets tested and proven over time? Is that really such a radical concept to contemplate on this science-oriented site? I’m not saying fringe concepts are always right; just that their existence on the ‘fringe’ by itself does not automatically disqualify them from eventually being right or being proved right.
Do we have to get into deeper weeds about the semantics of the word ‘fringe’ here, or into the history of science, or can we drop it now?
My thanks to Gavin for his response in #92, about the “mini ice age” twaddle, which (sadly) will now become the darling of the denialsphere for the next 15 years. I wanted to touch base on one of his statements, to ensure that I understood it correctly (and anyone can answer it — it doesn’t have to be Gavin.)
Gavin said, “It’s a statistical projection with no physics.” I take this to mean it is rather like the “money ball” analyses in baseball: this is how the numbers stack up, but we’ve no underlying mechanism (no physics) to explain what, how, or why?
[Response: People have ideas – but there is a clear difference between predictions based on physical understanding and modeling (like a numerical weather forecast), and ones based on statistical fits. The latter can be useful (for instance, ENSO forecasting uses this technique), and the stats can often give insight into the physics. However, since you can fit existing data to an arbitrary precision using statistical models, their credibility is only determined by their skill in forecasting. And for this case, that remains to be seen. – gavin]
Thanks!
siddsays
Re: rain on Greenland
Doyle et al. doi:10.1038/NGEO2482
Authors include Box and some of the usual suspects.
” … our findings portend a previously unforeseen vulnerability of the Greenland ice sheet to climate change.”
“… melt rates … were unusually sustained throughout both day and night by enhanced long-wave radiation and turbulent heat fluxes [16,17] associated with the advection of warm, moist air into the region … ”
” … the heat released by rain freezing into the surface snowpack enhanced melt above the snowline …”
“Owing to the ice sheet’s hypsometry, the surface area that receives precipitation as rain and is exposed to melt increases nonlinearly with a rising freezing level … ”
” … condensation at the ice surface resulted in an increased—and abnormally positive—latent heat flux …”
” … three previous late-summer acceleration and uplift events identified on the GIS in recent studies [14,33,34] can, with hindsight, now be reinterpreted as cyclonic rainfall/melt events … ”
” … modelling [42] indicates that the net annual flow and discharge of the GIS is indeed sensitive to and will increase in response to a greater frequency and spatial extent of high-magnitude runoff events anticipated under a warmer climate.”
Reference 42 is to Bougamont (doi:10.1038/ncomms6052) on meltwater influence on flow over soft beds.
The Doyle paper ends with:
” … the seasonal distribution of rainfall has already increased over the past thirty years, with a tendency for a higher proportion of rain falling later in the season (Fig. 5 and Supplementary Fig. 8) when the subglacial drainage system is likely to be highly sensitive to water inputs. A larger fraction of precipitation already falls as rain across the GIS (ref. 46), and rain now falls at higher elevations (Fig. 5c) where the ice sheet is responsive to increased runoff [41]. Cyclonic-induced runoff events may therefore play a more prominent role in the mass balance and dynamics of the GIS than they have previously … ”
A noticeable omission in the reference list is Neff,2014
doi:10.1002/2014JD021470
who wrote about an atmospheric river hitting Greenland during the 2012 event, and similarities to 1889, among other things.
sidd
wmmbbsays
Why does land use change, especially deforestation, have a slight cooling effect? I would expect, with the lesser uptake of CO2, the opposite would apply.
[Response: This experiment was only looking at the impact of the changed land surface (albedo, evaporation etc.). It doesn’t include the impacts on the carbon cycle, which are subsumed into the GHG-only simulations. Breaking the contributions down by process, as opposed to mechanism, is another way to do this of course, but requires a different setup. -gavin]
(That’s Doyle et al, Nature Geoscience (2015) doi:10.1038/ngeo2482.)
Which, inter alia, says:
Here we present measurements of ice velocity, subglacial water pressure and meteorological variables from the western margin of the Greenland ice sheet during a week of warm, wet cyclonic weather in late August and early September 2011. We find that extreme surface runoff from melt and rainfall led to a widespread acceleration in ice flow that extended 140 km into the ice-sheet interior. We suggest that the late-season timing was critical in promoting rapid runoff across an extensive bare ice surface that overwhelmed a subglacial hydrological system in transition to a less-efficient winter mode… our findings portend a previously unforeseen vulnerability of the Greenland ice sheet to climate change.
A link, clickable on the words “A new study” at the beginning of paragraph 4, takes you to the complete paper. It’s particularly apropos in the context of Omega’s comment at #104, especially:
“I think the fact that fastflow episodes are a summer phenomena suggests the liquid water is lost fairly quickly, which if true is reassuring, since if it pooled from year to year basal sliding resistance could be lost.”
Omega’s condition of ‘fastflow episodes as summer phenomena’ may be met less frequently over coming decades, apparently. And unfortunately.
How long would you expect to need to take data before having enough of an idea to do statistics on that?
NISTAR is an active cavity radiometer designed to measure the energy reflected and emitted from the entire sunlit face of the Earth from its orbit around the Lagrangian point 1 (L1). L1 is a neutral gravity point between Earth and the sun. This position offers a unique continuous view of the Earth at from sunrise to sunset.
This measurement will improve our understanding of the effects of changes to Earth’s reflected and emitted radiation (radiance) caused by human activities and natural phenomena. This information can be used for climate science applications.
The term Active Cavity Radiometer (ACR) was assigned by its inventor, Dr. Richard C. Willson of Columbia University, and earlier generations of the ACR were flown on the Solar Max and ACRIM (Active Cavity Radiometer Irradiance Monitor) missions. “NISTAR is unique in that it measures the entire sunlit Earth at the same time,” said Mark LaPole, Director of Space Products, Ball Aerospace, Boulder, Colorado. “The accuracy requirements were developed by the NISTAR Principal Investigators, Dr. Steven R. Lorentz and Dr. Joseph P. Rice of NIST.”
NISTAR was designed and built between 1999 and 2001 by Ball Aerospace and Technology Corporation working with the National Institute of Standards and Technology (NIST), Gaithersburg, Maryland and the Scripps Institution of Oceanography who developed the Scripps-NIST advanced radiometer, or Scripps NISTAR instrument.
“NISTAR uses active cavity radiometers, that absorb all of the incident radiation in internal cavities and monitors the heater currents necessary to maintain the cavity at a constant measured temperature, thus determining the incident energy,” said Adam Szabo, DSCOVR Project Scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Recent ground recalibration of this instrument indicate that better than the required 1.5% absolute accuracy will be achieved.”
“NIST will be able to approximately separate the Earth’s radiant power from reflected solar energy by making measurements in three overlapping wavelength bands. This will be an important contribution to the Earth climate debate,” Szabo said.
The radiometer is based on the NIST electrical-substitution measurement approach and Ball modular instrument electronics technology from the Spitzer and CALIPSO missions. Ball performed the instrument system engineering, and designed, fabricated, and tested the NISTAR payload. NISTAR was calibrated at the world-class NIST SIRCUS (Spectral irradiance and radiance responsivity calibrations using uniform sources) facility.
And, recalling an answer Gavin gave me years ago, is there anything now, or coming, on the dark side of Earth to get the other half of the data set needed? Or anything that can be approximated from the narrow views of low Earth-orbiting instruments?
GISTEMP has posted for June 2015 with an anomaly of +0.76ºC. This is the equal hottest June on record (with 1998). It weighs in as the 28th hottest monthly anomaly on record but note that GISTEMP is now using ERSSTv4 which makes substantial changes to previous monthly anomaly rankings.
The rolling 12-month average anomaly stands at +0.788ºC which compares with the warmest calendar year (so far) on record of +0.755ºC (in 2014). With the MEI climbing above 2.0 in May/June this year (the last time that happened was May/June 1997), I feel we can confidently reckon to continued scorchio!!
“If anyone had predicted beforehand the kind of losses seen in Arctic sea ice extent and area in 2007 that actually occurred, they would have been way beyond ‘fringe’ ….”
Or not ‘way’, eh? To characterize the usefulness of models, it’d work better to keep the goalposts in one place — rather than changing the argument so people end up chasing the goalposts as they move around. That makes people give up. And the point is to stay involved and get a good idea what different models suggest, and see how reality looks — and then improve the models.
It’s easier to improve the rhetoric, but less convincing.
I don’t really see it as ‘yet another impact,’ but rather as a stark setting forth of the ‘big picture’ oceanic consequences we face under RCP 2.6 versus those expected under RCP 8.5.
“More than 100 days after it launched, NOAA’s Deep Space Climate Observatory (DSCOVR) satellite has reached its orbit position about one million miles from Earth.
“Once final instrument checks are completed, DSCOVR, which will provide improved measurements of solar wind conditions to enhance NOAA’s ability to warn of potentially harmful solar activity, will be the nation’s first operational space weather satellite in deep space. Its orbit between Earth and the sun is at a location called the Lagrange point 1, or L1, which gives DSCOVR a unique vantage point to see the Earth and sun.”
Aaron Lewissays
re 107 Hank, I have not seen that post in years either. But it was 2002, you asked for cites, and I referred you to the work of Ed Deming applied to the CT ice area data. It still works.
We used Deming’s models to forecast upsets of large industrial systems. We knew the statistics worked.
You do not think that I am every going to forget when and where I was told, “Such alarmism is unhelpful.”
Warming of oceans due to climate change is unstoppable, say US scientists
Seas will continue to warm for centuries even if manmade greenhouse gas emissions were frozen at today’s levels, say US government scientists
“Scientists said the consequences of those warmer ocean temperatures would be felt for centuries to come – even if there were immediate efforts to cut the carbon emissions fuelling changes in the oceans.
“I think of it more like a fly wheel or a freight train. It takes a big push to get it going but it is moving now and will contiue to move long after we continue to pushing it,” Greg Johnson, an oceanographer at Noaa’s Pacific Marine Environmental Laboratory, told a conference call with reporters.
“Even if we were to freeze greenhouse gases at current levels, the sea would actually continue to warm for centuries and millennia, and as they continue to warm and expand the sea levels will continue to rise,” Johnson said.”
Whilst overall extent is not falling spectacularly, as of the 15 July overall extent is the second highest for the post 2007 period and losses are average. Conditions within the peripheral region are not reflecting this.
The result is that as area is falling faster than extent the pack is dispersing as melt opens the gaps between floes and enhances melt ponding on the ice surface, both factors decrease albedo and increase absorption of insolation.
This export of multi year ice may make a repeat of 2012 hard to achieve, however a September low well below those of 2013 and 2014 seems highly likely and this September may see extent around, or below, that of 2007 or 2011. Another factor that will make 2012 hard to repeat is that the Fram Strait export of ice is not as strong as in 2012.
A major factor in the current situation is the summer pattern of negative AO index seen in summers (JJA) from 2007 to 2012.
This pattern creates a dipole between lows over coastal Siberia and the Arctic Ocean high, drawing in warm Pacific air mass and increasing Barents influx of ocean waters from the Pacific. It is also associated with mass loss increases from Greenland Hanna 2012 “The influence of North Atlantic atmospheric and oceanic forcing effects on 1900–2010 Greenland summer climate and ice melt/runoff”.
So despite overall extent not being indicative of strong losses later in July and August, the detail suggests that this is indeed likely.
2015 is becoming a very exciting melt season.
DPsays
Regards the Arctic Cryosphere I saw a mathematical model that had the Summer sea almost disappearing between 2020 and 2025. Can’t access it anymore but any opinions?
Jean-François Fleurysays
I have another subject. Well, Stefan Rahmstorf explained earlier that the cooling of North Atlantic subpolar gyre was caused by a weakening of AMOC. And with the following post, he expressed a temptative hypothesis about the winter cold gust on East American coast linked with the persistent cold anomaly in North Atlantic. That was very nice for the American followers but in Europe we are highly concerned about the consequences of the climatic impacts of this cold anomaly as we are potentially the first beneficiaries. Then, I wonder if the current drought in western Europe, at least in France, is due to this cold anomaly. Can it be explained by a reduced evaporation involving less latent heat which could fed the intensity of the low pressure area of North Atlantic? On the other hand, are the high pressure air masses stabilized by this, especially the polar ones which fed the “azorean anticyclone”? Is the polar jet-stream influenced by the cyclonic pattern imposed by the cold anomaly, which in turn reinforces the cyclonic pattern and the cold anomaly? Feel free to answer and thanks for reply.
Zachary Ostermansays
Hello guys, The media with some scientists are playing the tipping point card again.
Would you be inclinded to agree with them this time or does your past TP points still stand?
Here is the fundamental problem with Wadhams’ prediction: He is predicting that the average monthly extent for September will be less than 1 million sq km. (All numbers according to the NSIDC, and in millions of sq km.) Over the last 5 years, the latest date on which the daily extent has crossed below the September monthly extent was September 6th. (In 2010, the monthly extent for September 2010 was 4.92. On September 5, 2010, the extent was 4.925 and on September 6, 2010, it was 4.913.)
The current data for daily extent is that on July 16, 2015, the extent was 8.403. There are 52 days between July 16th and September 6th, meaning that to hit his prediction, the extent must reduce by 7.403 in 52 days, or at an average rate of 0.142 per day.
This rate is unheard of on any sustained basis. (There have been individual days with extent loss at this rate or even higher, but you are unlikely to find periods of even as long a week with this average rate.) In the last 45 days (since the start of June), there have been 5 individual days with extent loss of greater than 0.142. The longest span of consecutive days with this average rate is 2. Again, Wadhams’ prediction requires 52 consecutive days at this average rate.
Given the measured current extent, Wadhams’ prediction is just not credible.
This is before you get into the fact that in the typical year the rate of extent loss starts falling in late July as the angle of the sun gets lower and the insolation falls, followed by the temperature. There are exceptions. In 2012, the rate of loss stayed high through August, leading to the record low extent in September that year. Over the period from July 16, 2012 to September 1, 2012, the average daily extent loss was 0.088. Even the exceptions are nowhere near fast enough to get to 1 million sq km. And that’s before we consider the fact that 2012 had a head start of 0.797 on July 16.
There comes a point when all the arguments in the world about poor ice quality and high heat and slow melt in areas which are guaranteed to melt out anyway have to face the numbers. And the numbers say this prediction is not credible.
Lawrence Colemansays
128: or another way– if the entire world was deforested whilst the albedo would be significantly higher the draw down and natural sequestration of CO2 in flora would be dramatically decreased thus immediately increasing the atmospheric CO2 (since the oceans would be ‘saturated’ with CO2)and resulting temp to inhospitable levels. l
Guestsays
Is there a formula for getting a ballpark estimate of equilibrium (future) sea level rise per additional ppm of CO2 we add in the present?
Adam Ashsays
I think Wadhams’ prediction is coloured by his conviction that the potential for a significant methane release from the shallow waters of the Arctic ocean (and consequent 3 to 6 degree C temperature rise) is about 50/50, as of today.
With that probability in mind it is quite understandable that he sees a similar 50/50 chance of a significant ice loss anytime from today.
So I suspect his ‘method’ of arriving at an estimate of the end of melt season extent is predicated on an entirely different mechanism than the method used by other technicians in the art.
So rather than knocking his extent prediction, we could usefully discuss his anxiety about warming of the shallow waters and consequent methane release, rather than fretting about curve fitting past Extent and Area trends.
As Wadhams says, the consequences of Likelihood (currently 50/50, and increasing daily) multiplied by Cost of Consequences (+3C to +6C = an Extinction Event for us) is a very big value in any currency. It seems to me we need to be paying his point of view a bit more attention.
Edward Greischsays
143 OSweetMrMath: Has the temperature of the ice itself been measured?
Not to contradict you at all, but the concept of “Rotten ice” makes sense to me. I’m not an ice expert, and I wouldn’t walk on ice at all, much less drive on it, but ice can appear to be still OK just before it “suddenly” melts. If it has been above freezing for a few days but still looks solid, it isn’t. You only walk or drive on it if the temperature has stayed way below zero for the past week or more and the measured thickness is a foot or something. As I said, I’m not an ice expert.
There is a lot of lore to learn before doing anything on ice, and then you have to follow the rules while on the ice. There are a lot of old cars at the bottoms of lakes in snow country because people used to race cars on frozen lakes. There were still areas of open water or thin ice when most of the lake could be driven on.
I think Wadham was talking about the Arctic ocean ice being rotten. The thing 139 Chris Reynolds said about area vs extent should not be ignored. Has the temperature of the ice itself been measured? You want the ice to be very cold, like 30 below or colder, so that it will be rock hard. Warm ice gets mushy while still looking solid, and then it can be gone quickly.
So I am not making any predictions about the Arctic ocean ice.
Chuck Hughessays
“There comes a point when all the arguments in the world about poor ice quality and high heat and slow melt in areas which are guaranteed to melt out anyway have to face the numbers. And the numbers say this prediction is not credible.”
How much does all of this really matter? Do we KNOW that the Arctic will eventually be ice free? I think the consensus is that it will. If we have a few ice cubes left how much difference will that make as far as weather impacts? I think we’re kinda there already. My question is… what are the consequences of an ice free Arctic vs. what we’re already seeing? Any thoughts on that? Thanks
Taking the Arctic Ocean daily extent losses of 2012 from 15 July 2012 to 15 September 2012 and applying to 15 July 2015 extent, I need to multiply all losses by 1.58 to get 15 September 2015 extent down to 1 million kmsq.
Do you have a recent citation on that? I know it was believed to be true up to about a decade ago, but more recently I see mostly this sort of paper:
Modelling water flow under glaciers and ice sheets
Gwenn E. Flowers 4 March 2015.DOI: 10.1098/rspa.2014.0907
Humming Glaciers October 24, 2014, doi: 10.1130/G35994.1
Since such openings are being documented, I wonder what our prior and more reassuring assumptions failed to take into account.
#90-2: Dunno ’bout the actual science, but the abstracts says this:
“Zharkova and her colleagues derived their model using a technique called ‘principal component analysis’ of the magnetic field observations from the Wilcox Solar Observatory in California.”
So you’d have to think denialati will rush to denounce it–they’re all apparently convinced that PCA is just a recipe for hockey sticks. ;-)
> data visualizations
Here’s one that might be a useful model — it’s “property values by county” but something similar, once we have the ability to map by county, would be interesting for climate-related changes.
Applying the approach to, say, planting/growing zones could be interesting now.
http://www.citylab.com/housing/2015/07/mapping-the-us-by-property-value-instead-of-land-area/397841/
Aaron, the total heat available from surface meltwater is just its volume times the heat of fusion of water, and this assumes all the water is refrozen. Gravitational energy is much smaller than this sum.
It we are talking about heating the bulk of the ice, and not localized smaller volumes it would take a rather large amount of surface melting to make much of a dent in the “coldness” of the ice. By “coldness” here I mean how far below the pressure melting point the ice is at. I think for Greenland this is something like -30C to -50C, so a unit volume of meltwater can bring a few times its volume of ice up to the melting point -if it all refreezes at depth. Melting at the surface especially in the interior is going to be well under a meter per year, so the timescale for changing the ice from the dry to wet state should be several centuries or more.
Now, what is the fate of injected meltwater? Ultimately it either refreezes, in which case it serves as a heat source for the deep ice, or it flows out under the ice and makes it to the ocean (in which case its heat of fusion is not lost to the ice). I think the fact that fastflow episodes are a summer phenomena suggests the liquid water is lost fairly quickly, which if true is reassuring, since if it pooled from year to year basal sliding resistance could be lost.
Re:cold content of Greenland
Box is an author on a paper with Fettweis from a couple years ago on erosion of the “cold content” of the ice, although he was looking at drops in albedo. More recently Enderlin, Howat wrote a paper indicating surface mass balance had begun to dominate mass waste. Estimating that SMB is about 200 GT gives an upper limit on heat flux into the cold reervoir, ? Comparable to the albedo effect i think, but i have not immediately the references to hand.
hmmmm …
Citation: Dunse, T., Schellenberger, T., Hagen, J. O., Kääb, A., Schuler, T. V., and Reijmer, C. H.: Glacier-surge mechanisms promoted by a hydro-thermodynamic feedback to summer melt, The Cryosphere, 9, 197-215, doi:10.5194/tc-9-197-2015, 2015.
> Hank: You asked for cites, so you should remember it.
Your 2002 post? if you can find it, a link would be useful. I tried.
I would like to hear any expert opinions on what I have recently read concerning the state of the jetstream over Siberia at the moment (i.e. that it has fractured/disintegrated in defiance of all models, and now just appears chaotic…)
Is this true?
Is it a new (and unheard of) occurrence?
IF true, what might it portend?
or will it most likely just fix itself and carry on regardless…?
This being an open thread..
I see every now and then a graph on NASA servers being used as a “proof” that there has been some kind of change of view to greenhouse effect and planet’s energy balance at NASA
https://i1.wp.com/science-edu.larc.nasa.gov/EDDOCS/images/Erb/components2.gif
That is patently ridiculous claim but you see these.. (sigh)
I have not found any links from NASA to that particular file and thus cannot figure out the context of it.
My guess is that it has been part of energy balance presentation pages in 2012 or earlier and is a fragment that remains after other stuff had been removed in an update..
Any clue where the rest of this could be found, including how greenhouse effect gets linked to this presentation..?
[Response: This link http://science-edu.larc.nasa.gov/energy_budget/ is perhaps some context. As you say, there is nothing particularly radical about the graph. – gavin]
@88…There is a pretty clear difference between clinical paranoia and the paranoia exhibited by internet conspiracy theorists.
Talk like this is what led to the original article being “controversial” as it made some sort of “diagnosis” about individuals. It clearly did not except in the minds of those intentionally spreading mis/disinformation.
It is wrongheaded to suggest that the typical internet conspiracy theorist is mentally ill. It simply is not the case. That is not to say they are not totally wrong.
This same phenomenon occurs in every intro to abnormal psych course where every student sees themselves having the same symptoms as those diagnosed with the various psych disorders they are reading about.
Where did you read this?
What “moment” — calendar date — are they writing about?
You might look at http://earth.nullschool.net/#current/wind/isobaric/250hPa/orthographic=92.83,89.57,414 (click the word “earth” in lower left, to set the view, then reload the page) — that won’t tell you _what_ you’re seeing, though.
If you tell us where you read what you’re asking about, that will help figure out what _they_ are talking about, whoever they are. Or not, of course.
http://www.arcus.org/files/resize/sio/23168/sio_dynmodfig_final-700×394.png
… about half of the 2015 prediction uncertainty is due to irreducible errors while the other half is directly related to spread in model configurations and initial conditions. This leaves room for improvement …. In summary, as a whole, dynamic models predict a larger September sea ice extent with less spread than for 2014…..
hat tip to Crandles at Stoat’s.
Thanks Gavin.. The link you provided has the latest full picture. The thing “they” seem to stress is that there is no “backradiation” nor imbalance in that older diagram so NASA must have second thoughts.. Well, you cannot convince conspiracy theorists with “interesting” views to physics fundamentals.. ;)
“OMG. Just look at all the official models for Arctic sea ice included in the IPCC report in 2007 (AR4), and look at what actually happened to the ice in that and succeeding years.
Revisionist history seems to be rampant among certain quarters, here.” -Mr. Wili
As has been pointed out to you a few times Wili, models did predict rapid collapse, and thus were not fringe as you claimed. Your refusal to acknowledge that you were wrong is disappointing.
You like to move goal posts in your responses. I am sure your heart is in the right place, but tend towards doomerism at the annoyance of many in my opinion.
Comment by Omega Centauri — 12 Jul 2015 @ 7:08 PM
Re:cold content of Greenland
Box is an author on a paper with Fettweis from a couple years ago on erosion of the “cold content” of the ice,
Give the language a break- Warmists and Denialists are uncouth enough without opening the door to Coolthists .
I hope that knowledgeable people will comment about this gas explosion on a rhode island beach.
http://abcnews.go.com/US/rhode-island-beach-blast-thing-victim-remembers-explosion/story?id=32411543
re 103: Heat delivered into the ice does not have to melt it, only add enough heat to bring small volumes of ice close to their pressure melting point. Ice in these volumes will flow more rapidly, setting off fractures in their margins. Fracturing allows ice flow, and ice flow is work that can deliver large amounts of potential energy to small volumes of ice. Fractures in ice can concentrate the energy in the ice flow at the margins of the fractures to drive additional fracturing.
Outer ice acts as bulwarks supporting the central massif. Ultimately, the stress from the weight of the central massif puts a massive tension stress on the small volumes of the bulwarks structures, and they fracture.
Once the temperature of the ice rises to near its pressure melt point, the potential energy in the ice can fracture enough of the ice to produce a slurry. For the ice to fracture into a slurry that can flow on a 2% grade, only an infinitesimal amount of ice needs to melt.
for 0^) and Gavin:
That oversimplified “radiation budget” is within a grade-school-level Radiation Budget Education Page linked from this section where it says:
It says:
Regrettably this page fails to meet the criterion attributed, apparently apocryphally, to Einstein: “Everything should be made as simple as possible, but not simpler.”
That’s hard to do, given that it’s a complex subject.
There’s a page aimed at teenagers that handles the basic information — greenhouse gases including water vapor are warmer than space or dry air.
http://mynasadata.larc.nasa.gov/804-2/1035-2/
but oddly (or not, as it’s a Forrest Mims page) it never explicitly says that the greenhouse gases, being warmer because they collected heat radiated from the surface, are radiating heat back toward the surface.
Perhaps that conclusion was left for the students?
Yet another impact from rising CO2:
Gattuso et al: Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios
Science 3 July 2015:
Vol. 349 no. 6243
DOI: 10.1126/science.aac4722
Speaking of “data visualization” there’s a new blocok of text appearing next to the Recent Comments containing the words “Tweet” and “SUMOME” — it appears to be an email harvesting tool, maybe from WordPress, maybe a hitchhiker. Poked at it a bit:
The marked block contains “Tweet SUMOME” (Tweet in green and underlined to indicate it is a link, but “SUMOME” in faint gray smaller text, not underlined, although it also is a link. The word “SUMOME” links to some kind of optimizing web page that says:
It offers to run Adobe Flash (persistently). Adblock doesn’t block it (yet) and NoScript doesn’t find it (yet).
I’m sure it’s only appearing there because it’s trying to serve us in a helpful way, to somebody; perhaps it’s a cookbook.
Re; Maunder Minimum and surface temperature
This link would seem to suggest much greater temperature drops during a Grand Solar Minimum. Any comments?
http://earthobservatory.nasa.gov/IOTD/view.php?id=7122
Recommended reading:
http://thinkprogress.org/climate/2015/07/13/3679662/global-warming-speed-up-not-ice-age/
Why does deforestation and land use in general have a slight cooling effect? I would have thought the opposite would be true, with greater reflection of infra-red radiation.
Re:”cold content” language
The phrase is not mine, take it up with Box et al. doi:10.5194/tc-6-821-2012
“In an example with realistic boundary conditions, the additional 148 EJ solar energy is sufficient to completely erode the “cold content” of the 1.494 × 106 km^2 accumulation area to a depth of 14 cm, assuming its temperature, density, and specific heat to be −10C, 360 kg/m^3, and 2110 J/(kg K) respectively.”
sidd
JMA just posted June as the hottest on record: http://ds.data.jma.go.jp/tcc/tcc/products/gwp/temp/jun_wld.html
On the other matter, it’s probably not worth dignifying the whiners with a response, but can we just point out that “fringe” does not mean non-existent. That there was a study 2006 and that its estimates were well outside of all those included in the ’07 IPCC report makes it by definition, ‘fringe.’ “Fringe,” after all, does not mean “non-existent”!
I concede that I was unaware of the study, and thank our uber-cyber-sleuth hank for ferreting it out. But its existence confirms rather than detracts from my general point…the report was clearly on the ‘fringe’ of all the reports included in the international report that most everyone looks to for the definition of the mainstream view on these things.
It was on the ‘fringe,’ and it was right (well, more accurate than all the other, more ‘main stream’ model included in the IPCC.) Do I really have to argue here that science is not determined by what is or is not ‘on the fringe’ of current thinking at any particular moment, but by what gets tested and proven over time? Is that really such a radical concept to contemplate on this science-oriented site? I’m not saying fringe concepts are always right; just that their existence on the ‘fringe’ by itself does not automatically disqualify them from eventually being right or being proved right.
Do we have to get into deeper weeds about the semantics of the word ‘fringe’ here, or into the history of science, or can we drop it now?
My thanks to Gavin for his response in #92, about the “mini ice age” twaddle, which (sadly) will now become the darling of the denialsphere for the next 15 years. I wanted to touch base on one of his statements, to ensure that I understood it correctly (and anyone can answer it — it doesn’t have to be Gavin.)
Gavin said, “It’s a statistical projection with no physics.” I take this to mean it is rather like the “money ball” analyses in baseball: this is how the numbers stack up, but we’ve no underlying mechanism (no physics) to explain what, how, or why?
[Response: People have ideas – but there is a clear difference between predictions based on physical understanding and modeling (like a numerical weather forecast), and ones based on statistical fits. The latter can be useful (for instance, ENSO forecasting uses this technique), and the stats can often give insight into the physics. However, since you can fit existing data to an arbitrary precision using statistical models, their credibility is only determined by their skill in forecasting. And for this case, that remains to be seen. – gavin]
Thanks!
Re: rain on Greenland
Doyle et al. doi:10.1038/NGEO2482
Authors include Box and some of the usual suspects.
” … our findings portend a previously unforeseen vulnerability of the Greenland ice sheet to climate change.”
“… melt rates … were unusually sustained throughout both day and night by enhanced long-wave radiation and turbulent heat fluxes [16,17] associated with the advection of warm, moist air into the region … ”
” … the heat released by rain freezing into the surface snowpack enhanced melt above the snowline …”
“Owing to the ice sheet’s hypsometry, the surface area that receives precipitation as rain and is exposed to melt increases nonlinearly with a rising freezing level … ”
” … condensation at the ice surface resulted in an increased—and abnormally positive—latent heat flux …”
” … three previous late-summer acceleration and uplift events identified on the GIS in recent studies [14,33,34] can, with hindsight, now be reinterpreted as cyclonic rainfall/melt events … ”
” … modelling [42] indicates that the net annual flow and discharge of the GIS is indeed sensitive to and will increase in response to a greater frequency and spatial extent of high-magnitude runoff events anticipated under a warmer climate.”
Reference 42 is to Bougamont (doi:10.1038/ncomms6052) on meltwater influence on flow over soft beds.
The Doyle paper ends with:
” … the seasonal distribution of rainfall has already increased over the past thirty years, with a tendency for a higher proportion of rain falling later in the season (Fig. 5 and Supplementary Fig. 8) when the subglacial drainage system is likely to be highly sensitive to water inputs. A larger fraction of precipitation already falls as rain across the GIS (ref. 46), and rain now falls at higher elevations (Fig. 5c) where the ice sheet is responsive to increased runoff [41]. Cyclonic-induced runoff events may therefore play a more prominent role in the mass balance and dynamics of the GIS than they have previously … ”
A noticeable omission in the reference list is Neff,2014
doi:10.1002/2014JD021470
who wrote about an atmospheric river hitting Greenland during the 2012 event, and similarities to 1889, among other things.
sidd
Why does land use change, especially deforestation, have a slight cooling effect? I would expect, with the lesser uptake of CO2, the opposite would apply.
[Response: This experiment was only looking at the impact of the changed land surface (albedo, evaporation etc.). It doesn’t include the impacts on the carbon cycle, which are subsumed into the GHG-only simulations. Breaking the contributions down by process, as opposed to mechanism, is another way to do this of course, but requires a different setup. -gavin]
More Greenland Ice Sheet vulnerability:
http://www.nature.com/articles/ngeo2482
(That’s Doyle et al, Nature Geoscience (2015) doi:10.1038/ngeo2482.)
Which, inter alia, says:
Discussed in the Guardian here:
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/jul/14/global-warming-is-causing-rain-to-melt-the-greenland-ice-sheet
A link, clickable on the words “A new study” at the beginning of paragraph 4, takes you to the complete paper. It’s particularly apropos in the context of Omega’s comment at #104, especially:
“I think the fact that fastflow episodes are a summer phenomena suggests the liquid water is lost fairly quickly, which if true is reassuring, since if it pooled from year to year basal sliding resistance could be lost.”
Omega’s condition of ‘fastflow episodes as summer phenomena’ may be met less frequently over coming decades, apparently. And unfortunately.
So, speaking of data visualization — how will you visualize results from this instrument on the whatchamacallit satellite?
http://www.nasa.gov/content/goddard/noaas-dscovr-nistar-instrument-watches-earths-budget/
How long would you expect to need to take data before having enough of an idea to do statistics on that?
And, recalling an answer Gavin gave me years ago, is there anything now, or coming, on the dark side of Earth to get the other half of the data set needed? Or anything that can be approximated from the narrow views of low Earth-orbiting instruments?
GISTEMP has posted for June 2015 with an anomaly of +0.76ºC. This is the equal hottest June on record (with 1998). It weighs in as the 28th hottest monthly anomaly on record but note that GISTEMP is now using ERSSTv4 which makes substantial changes to previous monthly anomaly rankings.
The rolling 12-month average anomaly stands at +0.788ºC which compares with the warmest calendar year (so far) on record of +0.755ºC (in 2014). With the MEI climbing above 2.0 in May/June this year (the last time that happened was May/June 1997), I feel we can confidently reckon to continued scorchio!!
“If anyone had predicted beforehand the kind of losses seen in Arctic sea ice extent and area in 2007 that actually occurred, they would have been way beyond ‘fringe’ ….”
Or not ‘way’, eh? To characterize the usefulness of models, it’d work better to keep the goalposts in one place — rather than changing the argument so people end up chasing the goalposts as they move around. That makes people give up. And the point is to stay involved and get a good idea what different models suggest, and see how reality looks — and then improve the models.
It’s easier to improve the rhetoric, but less convincing.
Here’s another prediction to evaluate — from 12 December 2007: Arctic summers ice-free ‘by 2013’…. may be our projection of 2013 is already too conservative.”
Echo chamber of outrage: Ars attends a climate skeptics’ summit
#119–Thanks, AIC. The paper can be seen here:
http://sciences.blogs.liberation.fr/files/gattuso150703.pdf
I don’t really see it as ‘yet another impact,’ but rather as a stark setting forth of the ‘big picture’ oceanic consequences we face under RCP 2.6 versus those expected under RCP 8.5.
#130–Let’s hope they get it launched before Congress can defund it. (OK, probably not a realistic snark, but…)
#130 and my snarky comment:
Definitely not a realistic snark!
http://www.nesdis.noaa.gov/DSCOVR/
“More than 100 days after it launched, NOAA’s Deep Space Climate Observatory (DSCOVR) satellite has reached its orbit position about one million miles from Earth.
“Once final instrument checks are completed, DSCOVR, which will provide improved measurements of solar wind conditions to enhance NOAA’s ability to warn of potentially harmful solar activity, will be the nation’s first operational space weather satellite in deep space. Its orbit between Earth and the sun is at a location called the Lagrange point 1, or L1, which gives DSCOVR a unique vantage point to see the Earth and sun.”
re 107 Hank, I have not seen that post in years either. But it was 2002, you asked for cites, and I referred you to the work of Ed Deming applied to the CT ice area data. It still works.
We used Deming’s models to forecast upsets of large industrial systems. We knew the statistics worked.
You do not think that I am every going to forget when and where I was told, “Such alarmism is unhelpful.”
http://www.theguardian.com/environment/2015/jul/16/warming-of-oceans-due-to-climate-change-is-unstoppable-say-us-scientists?CMP=twt_environment
Warming of oceans due to climate change is unstoppable, say US scientists
Seas will continue to warm for centuries even if manmade greenhouse gas emissions were frozen at today’s levels, say US government scientists
“Scientists said the consequences of those warmer ocean temperatures would be felt for centuries to come – even if there were immediate efforts to cut the carbon emissions fuelling changes in the oceans.
“I think of it more like a fly wheel or a freight train. It takes a big push to get it going but it is moving now and will contiue to move long after we continue to pushing it,” Greg Johnson, an oceanographer at Noaa’s Pacific Marine Environmental Laboratory, told a conference call with reporters.
“Even if we were to freeze greenhouse gases at current levels, the sea would actually continue to warm for centuries and millennia, and as they continue to warm and expand the sea levels will continue to rise,” Johnson said.”
The peripheral Arctic Basin is the region which plays the biggest role in the setting of the summer Arctic sea ice minimum. It is the area covered by the Beaufort, Chukchi, East Siberian and Laptev Seas, shown in this graphic adapted from Cryosphere Today.
http://1.bp.blogspot.com/-FtpBv1CvIgA/VZwV312FBeI/AAAAAAAACSE/6vTJwoA-x-w/s1600/Peripheral%2BSeas.png
Whilst overall extent is not falling spectacularly, as of the 15 July overall extent is the second highest for the post 2007 period and losses are average. Conditions within the peripheral region are not reflecting this.
Area and extent are explained here:
http://nsidc.org/arcticseaicenews/faq/#area_extent
Compactness is the ratio area/extent and is a measure of dispersion of the ice.
Extent for the peripheral region.
https://farm1.staticflickr.com/435/19746881732_62f86bfabf_o.png
Extent is falling, and after a slow start the anomalies show it is falling towards that of 2007, 2011, and 2012.
Area is falling fast and tracking 2007, 2011 and 2012 in anomaly.
https://farm1.staticflickr.com/407/19566091208_e94ec1ccc3_o.png
The result is that as area is falling faster than extent the pack is dispersing as melt opens the gaps between floes and enhances melt ponding on the ice surface, both factors decrease albedo and increase absorption of insolation.
So compactness falls.
https://farm1.staticflickr.com/306/19727944816_0eb0ce95f9_o.png
And with this fall insolation absorption increases under largely clear skies, with the resultant thinning priming the ice for strong recession in the weeks to come.
2015 saw a greater export of thicker more melt resistant multi year ice into the Pacific sector of the Arctic Ocean. This is seen in the drift age model:
ftp://ccar.colorado.edu/pub/tschudi/iceage/gifs/
(Week 27)
And in ASCAT, e.g. Day 100 of 2012 and 2015.
http://manati.star.nesdis.noaa.gov/ascat_images/ice_image/
ASCAT shows multi year ice as brighter than the first year ice growth.
This export of multi year ice may make a repeat of 2012 hard to achieve, however a September low well below those of 2013 and 2014 seems highly likely and this September may see extent around, or below, that of 2007 or 2011. Another factor that will make 2012 hard to repeat is that the Fram Strait export of ice is not as strong as in 2012.
A major factor in the current situation is the summer pattern of negative AO index seen in summers (JJA) from 2007 to 2012.
July average SLP anomaly for 2007 to 2012.
https://farm1.staticflickr.com/524/19747236722_20d5f16b5c_o.png
1 to 14 July average SLP for 2015.
https://farm1.staticflickr.com/463/19567876779_e70f68497c_o.gif
This pattern creates a dipole between lows over coastal Siberia and the Arctic Ocean high, drawing in warm Pacific air mass and increasing Barents influx of ocean waters from the Pacific. It is also associated with mass loss increases from Greenland Hanna 2012 “The influence of North Atlantic atmospheric and oceanic forcing effects on 1900–2010 Greenland summer climate and ice melt/runoff”.
So despite overall extent not being indicative of strong losses later in July and August, the detail suggests that this is indeed likely.
2015 is becoming a very exciting melt season.
Regards the Arctic Cryosphere I saw a mathematical model that had the Summer sea almost disappearing between 2020 and 2025. Can’t access it anymore but any opinions?
I have another subject. Well, Stefan Rahmstorf explained earlier that the cooling of North Atlantic subpolar gyre was caused by a weakening of AMOC. And with the following post, he expressed a temptative hypothesis about the winter cold gust on East American coast linked with the persistent cold anomaly in North Atlantic. That was very nice for the American followers but in Europe we are highly concerned about the consequences of the climatic impacts of this cold anomaly as we are potentially the first beneficiaries. Then, I wonder if the current drought in western Europe, at least in France, is due to this cold anomaly. Can it be explained by a reduced evaporation involving less latent heat which could fed the intensity of the low pressure area of North Atlantic? On the other hand, are the high pressure air masses stabilized by this, especially the polar ones which fed the “azorean anticyclone”? Is the polar jet-stream influenced by the cyclonic pattern imposed by the cold anomaly, which in turn reinforces the cyclonic pattern and the cold anomaly? Feel free to answer and thanks for reply.
Hello guys, The media with some scientists are playing the tipping point card again.
Would you be inclinded to agree with them this time or does your past TP points still stand?
http://www.theguardian.com/environment/2015/jul/16/warming-of-oceans-due-to-climate-change-is-unstoppable-say-us-scientists
Here is the fundamental problem with Wadhams’ prediction: He is predicting that the average monthly extent for September will be less than 1 million sq km. (All numbers according to the NSIDC, and in millions of sq km.) Over the last 5 years, the latest date on which the daily extent has crossed below the September monthly extent was September 6th. (In 2010, the monthly extent for September 2010 was 4.92. On September 5, 2010, the extent was 4.925 and on September 6, 2010, it was 4.913.)
The current data for daily extent is that on July 16, 2015, the extent was 8.403. There are 52 days between July 16th and September 6th, meaning that to hit his prediction, the extent must reduce by 7.403 in 52 days, or at an average rate of 0.142 per day.
This rate is unheard of on any sustained basis. (There have been individual days with extent loss at this rate or even higher, but you are unlikely to find periods of even as long a week with this average rate.) In the last 45 days (since the start of June), there have been 5 individual days with extent loss of greater than 0.142. The longest span of consecutive days with this average rate is 2. Again, Wadhams’ prediction requires 52 consecutive days at this average rate.
Given the measured current extent, Wadhams’ prediction is just not credible.
This is before you get into the fact that in the typical year the rate of extent loss starts falling in late July as the angle of the sun gets lower and the insolation falls, followed by the temperature. There are exceptions. In 2012, the rate of loss stayed high through August, leading to the record low extent in September that year. Over the period from July 16, 2012 to September 1, 2012, the average daily extent loss was 0.088. Even the exceptions are nowhere near fast enough to get to 1 million sq km. And that’s before we consider the fact that 2012 had a head start of 0.797 on July 16.
There comes a point when all the arguments in the world about poor ice quality and high heat and slow melt in areas which are guaranteed to melt out anyway have to face the numbers. And the numbers say this prediction is not credible.
128: or another way– if the entire world was deforested whilst the albedo would be significantly higher the draw down and natural sequestration of CO2 in flora would be dramatically decreased thus immediately increasing the atmospheric CO2 (since the oceans would be ‘saturated’ with CO2)and resulting temp to inhospitable levels. l
Is there a formula for getting a ballpark estimate of equilibrium (future) sea level rise per additional ppm of CO2 we add in the present?
I think Wadhams’ prediction is coloured by his conviction that the potential for a significant methane release from the shallow waters of the Arctic ocean (and consequent 3 to 6 degree C temperature rise) is about 50/50, as of today.
With that probability in mind it is quite understandable that he sees a similar 50/50 chance of a significant ice loss anytime from today.
So I suspect his ‘method’ of arriving at an estimate of the end of melt season extent is predicated on an entirely different mechanism than the method used by other technicians in the art.
So rather than knocking his extent prediction, we could usefully discuss his anxiety about warming of the shallow waters and consequent methane release, rather than fretting about curve fitting past Extent and Area trends.
As Wadhams says, the consequences of Likelihood (currently 50/50, and increasing daily) multiplied by Cost of Consequences (+3C to +6C = an Extinction Event for us) is a very big value in any currency. It seems to me we need to be paying his point of view a bit more attention.
143 OSweetMrMath: Has the temperature of the ice itself been measured?
Not to contradict you at all, but the concept of “Rotten ice” makes sense to me. I’m not an ice expert, and I wouldn’t walk on ice at all, much less drive on it, but ice can appear to be still OK just before it “suddenly” melts. If it has been above freezing for a few days but still looks solid, it isn’t. You only walk or drive on it if the temperature has stayed way below zero for the past week or more and the measured thickness is a foot or something. As I said, I’m not an ice expert.
There is a lot of lore to learn before doing anything on ice, and then you have to follow the rules while on the ice. There are a lot of old cars at the bottoms of lakes in snow country because people used to race cars on frozen lakes. There were still areas of open water or thin ice when most of the lake could be driven on.
I think Wadham was talking about the Arctic ocean ice being rotten. The thing 139 Chris Reynolds said about area vs extent should not be ignored. Has the temperature of the ice itself been measured? You want the ice to be very cold, like 30 below or colder, so that it will be rock hard. Warm ice gets mushy while still looking solid, and then it can be gone quickly.
So I am not making any predictions about the Arctic ocean ice.
“There comes a point when all the arguments in the world about poor ice quality and high heat and slow melt in areas which are guaranteed to melt out anyway have to face the numbers. And the numbers say this prediction is not credible.”
How much does all of this really matter? Do we KNOW that the Arctic will eventually be ice free? I think the consensus is that it will. If we have a few ice cubes left how much difference will that make as far as weather impacts? I think we’re kinda there already. My question is… what are the consequences of an ice free Arctic vs. what we’re already seeing? Any thoughts on that? Thanks
To add to OSweetMrMath’s comment…
Taking the Arctic Ocean daily extent losses of 2012 from 15 July 2012 to 15 September 2012 and applying to 15 July 2015 extent, I need to multiply all losses by 1.58 to get 15 September 2015 extent down to 1 million kmsq.
And here is what the graph looks like for the Arctic Ocean.
http://3.bp.blogspot.com/-7kYREUZ1q_8/Vao2aGm_RdI/AAAAAAAACUI/wNUfoepG1q4/s1600/1M%2Bkmsq.png
It just isn’t going to happen.
More fun with the cryosphere:
http://www.washingtonpost.com/news/energy-environment/wp/2015/07/17/the-troubling-reason-why-greenland-may-melt-faster-than-expected/
Greenland goes Wicked Witch of the West: Deep, craggy, and melting.