In another forum (on a planet far, far away), the following quote recently came up:
….the combined effect of these greenhouse gases is to warm Earth’s atmosphere by about 33 ºC, from a chilly -18 ºC in their absence to a pleasant +15 ºC in their presence. 95% (31.35 ºC) of this warming is produced by water vapour, which is far and away the most important greenhouse gas. The other trace gases contribute 5% (1.65 ºC) of the greenhouse warming, amongst which carbon dioxide corresponds to 3.65% (1.19 ºC). The human-caused contribution corresponds to about 3% of the total carbon dioxide in the present atmosphere, the great majority of which is derived from natural sources. Therefore, the probable effect of human-injected carbon dioxide is a miniscule 0.12% of the greenhouse warming, that is a temperature rise of 0.036 ºC. Put another way, 99.88% of the greenhouse effect has nothing to do with carbon dioxide emissions from human activity8.
We’ve discussed the magnitude of the greenhouse effect before, but it might be helpful to step through this ‘back-of-the-agenda’ calculation and see what the numbers really give. (Deltoid has also had a go at some of these mis-statements).
The quote comes from a lecture by an Australian climate ‘contrarian’ and frequent contributor to the southern hemisphere op-ed pages. Where did he get this from? One might assume that reference ‘8’ was a scientific text, but one would assume wrong. It was in fact our old friend at Fox News, who may in turn have picked up his (junk)science from here. It is not clear whether this is the original source, but it’s close enough.
So, starting at the top:
- “33 ºC” is the difference between the mean surface air temperature of the planet and the blackbody radiating temperature (i.e. the temperature a blackbody would need to radiate at to be in equilibrium with the incoming solar radiation given an albedo of about 0.3). So far so good. While that is one way to assess the strength of the basic greenhouse effect, another one is measure the amount of long wave radiation from the surface that is absorbed in the atmosphere (by greenhouse gases (incl. water vapour), clouds, aerosols, etc.). That is currently about 150 W/m2 and would be zero with no greenhouse effect at all.
- “95% of this warming is caused by water vapour”. This is sourced to a couple of chaps who may have worked for Accu-Weather, but a) is misquoted – their ’90-95%’ is for both water vapour and clouds, and b) just wrong and c) irrelevant anyway.
Dealing with b) first, if you remove all water vapour and clouds you still absorb about 34% of the long wave radiation, and conversely, if you only have water vapour and clouds you absorb 85% (calculations here). Thus the effect of water vapour and clouds is between 66 and 85% – the range being due to the spectral overlaps with the other absorbers. These calculations were done with the GISS GCM radiation code, which matches line-by-line codes to about 10% – but the numbers are very similar to Ramanathan and Coakley (1978), and so probably aren’t too far off what you would get with any decent radiation code. I’ll get to ‘c)’ below…. - “The other trace gases contribute 5% … amongst which carbon dioxide corresponds to 3.65%”. That is just 100 minus 95% of course, but really it should be 15 to 34% – of which CO2 on its own is between 9 and 26% (op cit). If you were to naively estimate the total temperature contribution of the CO2 it would be between 3 and 9 ºC – but see below.
- “The human-caused contribution corresponds to about 3% of the total carbon dioxide in the present atmosphere,”. This one is blatantly false and is erroneously credited to the US Dept. of Energy in the original source (their Table 1)! The ‘3%’ number actually comes from comparing the human emissions with the gross emissions from natural sources while neglecting to consider the large natural sink. Because of the rapid cycling between the biosphere, the atmosphere and the upper ocean, that is an irrelevant comparison – kind of like comparing the interest on your bank account and your salary and expecting to be able to say something about your savings without thinking about your spending. The correct statement is that CO2 is around 30% higher than it was in the pre-industrial period, and all of that rise is due to human emissions (fossil fuel use and deforestation principally).
- “Therefore, the probable effect of human-injected carbon dioxide is a miniscule 0.12% of the greenhouse warming”. That’s just 0.03*0.0365 of course – but even that is calculated wrong (it should be 0.11% by my calculator). But from our numbers, it would be between 3 and 8%.
- “a temperature rise of 0.036 ºC”. More like 1-2.6 ºC actually, but although this gives numbers that are in the ballpark of the IPCC estimates (0.6 to 1.7 ºC warming for an increase of 30% in CO2 at equilibirum) this is not a sensible way to calculate climate sensitivty.
Why do I claim this is an irrelevant and not very sensible calculation? Firstly, it assumes linearity – all of the gases contributing according to their effects today when it is obvious that overlaps and saturation effects are large and important, and more importantly, it ignores feedbacks. The calculation above gives the impression that what you are calculating is the change of temperature that would result if you remove all the CO2. But since water vapour concentration is a feedback not a forcing, it can’t be assumed to remain constant as the planet cools. Water vapour does in fact change (roughly keeping relative humidity, as opposed to specific humidity, constant) and this has been shown in the real world as a function of volcanic cooling (Soden et al, 2002) and for longer term trends (Soden et al, 2005, discussed here), and is well reproduced in climate models.
What then is an appropriate calculation? Well, it’s simply the estimate of climate sensitivity for the present climate – how much would you expect the planet to warm if you doubled CO2? We’ve discussed this numerous times before, and in my opinion the best answer so far comes from looking at the difference between the last glacial period and the modern era – this gives a number around 3 +/- 1 ºC at doubling.
For the 30% rise in CO2 there has been so far, that would imply that would represent around 3% of the natural greenhouse effect – a good order of magnitude bigger than that suggested above. Of course, this is at equilibrium and not applicable to a transient change. If one takes into account the human-induced changes in the other GHGs (CH4, N2O, CFCs), you’d get something like double that. Given that even a 5 or 6 ºC cooling was associated with the huge ice sheets 20,000 years ago, and that 33 ºC cooling would reduce our planet to a near-snowball-like state, a potential increase of 5 to 6% of the natural greenhouse effect is not to be sniffed at… nor dismissed as irrelevent with highly misleading arithmetic.
One could make the point that my calculations are ‘just another web page’ no more and no less authoritative than the links above. In some sense that is correct (though I’d argue my sourcing is a little better!). But you will never find a peer-reviewed rebuttal of such a bizarre line of reasoning as we are dealing with here – basically because such a line of reasoning is highly unlikely to make it past peer-review itself. There are innumerable ‘proper’ references to estimates of the climate sensitivity though, and one should indeed hesitate to accept calculations like this example over the mass of peer reviewed studies.
Re #137:
Chris, the IPCC graph gives the forcings, not the feedbacks. In the case of solar forcing, there is an observed statistically significant cloud feedback: a variation of +/- 2% in low cloud cover over the past two sun cycles (see Figure 1 in Kristjansson, and point [11] for a proposal of the physics which may explain the change).
The reduction of low clouds during the solar high gives a variation of 0.1 K in global SST within a few years. This can go up to 0.3 K in some cycles and up to 0.5 K in the tropics, all within the few years between solar minimum and maximum. The change of +/- 2% in global cloud cover makes a difference of app. +/- 2 W/m2 at the surface, more near the equator, less toward the poles. Thus a strong fortifying factor for the original forcing.
This is what happened within the last two solar cycles, for which we have rather accurate data for cloud cover, solar radiation and SST’s. More difficult to interpret is what happened before the satellite era. We have several indices for solar activity, but none of them are 100% correlated to solar radiation strength and/or effects on climate. We only know that there is a quite good correlation between them at one side and climate over the pre-industrial period since the Maunder Minimum (sunspots were absent during that period). The estimated impact of the change in solar activity largely depends of which reconstruction you use for solar at one side (0.2-0.6 W/m2 increase since the MM) and which temperature reconstruction you use for the same period (0.2-1.0 K increase since the MM, of which 0.1 K due to volcanoes, the rest is solar).
Some climate models expect similar changes in cloud cover for increases in GHGs as is the case for solar (thus a positive feedback), but until now, there is no proof for such a relation, and in two climatically important area’s (the tropics and the Arctic), cloud change calculations in current models are proven wrong. See for the tropics Wielicki ea. and Allan and Slingo
JimR wrote (#141): “All sources agree that the 1920s to 1930s showed a slight lull in solar activity, lower than at anytime since 1940”.
The NASA table of “GLOBAL Temperature Anomalies”, GHCN 1880-12/2005 (meteorological stations only) at:
http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt
shows that the top five largest positive anamolies for July for the 100 year period from 1880-1979 are:
1941 .36
1936 .33
1940 .31
1977 .27
1931 .20
The NASA data shows that global temperatures from land area stations in the 1930s and early 1940s as shown above were the warmest of record for July up to those dates. Those warm Julys in the 1930s and early 1940s remained the warmest Julys of record until 1981, globally (not local or regional warmth).
This ongoing debate about whether humans are responsible for global warming is really starting to anger me. It matters not who or what is to blame. Global warming is real. We have to start making plans now for the changes that are going to be taking place in the near future. The oceans will rise flooding many of our costal cities. Farmland areas will have to be changed. We need a policy to start preparing for the changes. We do not need to sit around debating who or what’s to blame!
re 141
NASA data shows that global temperatures from land area climate stations for 1931 and 1936 were the warmest of record for July up to those dates. http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt
Right on, scalpmed! Adapting to climate change as best we can is the only realistic strategy — assuming we have reached a point of no return, as I believe we have. A panic attempt to do the impossible, i.e, turn our fossil-fuel-based economy around on a dime, is absurd on the face of it — like King Canute commanding the seas to retreat.
By all means let us work make the world safe for nuclear power, economize on our personal consumption, strive for greater energy efficiency — but let us not kid ourselves. We are also going to have to move to higher ground, build sea walls, use more air-conditioning, and in general build a manifold cultural response to meet the inevitable.
Re #144 (2):
Pat, this may help to reconstruct climate in the Mid-West USA. Abstract from Perry:
Re: 147
Public opinion is fickle – in fact it’s a bit of a herd instinct. Saying the debate is over will not make it so. The real test of public opinions is at the poling stations where people vote in secret. No party here in the UK and I suspect in the US, is likely to get into power on a policy that would make real cuts in CO2 – like doubling the price of petrol and heating oil. When the UK government tried to hike the price of petrol there was a spontaneous revolt amongst drivers that very near brought the county to a standstill and the government was forced into a U turn.
I must have an exceptional group of friends, family and acquaintances because not one has a considered opinion that AGW is proven to be the main reason for the current warming. The few that believe it is quite openly say that it must be so if the “experts” say so.
Re #153 and #155,
The discussion of the relative contribution is important, as that influences the amplitude of the warming in the coming century. Or the difference between a benign warming and a possible disaster.
No matter the result, we need to look for fossil fuel alternatives asap, even if the contribution of GHGs would be minimal, in any case for geo-political reasons.
Btw, we have some time to adapt to sea level changes, as getting wet feet from climate change, even in the worst scenario, is not before the end of this century. Storm surge protection (where sea levels may go far higher than for climate induced sea levels in the foreseeable future), also protect to a large extent against sea level changes.
Re #148 Gavin’s comment:
Gavin, as far as I have read in many scientific works, the “consensus” between all solar scientists is that current solar activity is higher than in the Maunder Minimum and higher than in the first halve of the 20th century. That is based on several different types of proxies, of which climate is one of them (for the pre-industrial period). I have not seen any peer-reviewed article that points to a disconnection between sunspots/magnetic activity/nucleides and solar activity/irradiance/(pre-industrial) climate.
Of course, that can change with new evidence, but the probability that this will happen is comparable to the probability that there is no connection between CO2 levels and IR radiation/climate.
You are right that the possibility of a solar high compared to the past 8,000 years is more uncertain, as that is based on only one type of proxy.
Thus the confidence level of increased solar irradiance since the Maunder Minimum (and the first halve of the previous century) is high, but the scientific understanding of the mechanism involved, the amplitude of the change in long-term irradiation and the resulting influence on climate are still very uncertain.
Re #138 (answer by William)
As for a) and b), the Wikipedia report seems quite conclusive on the convergence of surface and tropospheric warming. However the surface warming falls a bit short of the lower predicted margin of 0.2 oC warming per decade and I don’t quite see a conclusive faster warming of the lower troposphere. Of course I am in no position to discuss your or Wikipedia’s assertions. But if I do an always healthy check of alternative sources I surprisingly find things like this: http://www.climatescience.gov/Library/sap/sap1-1/public-review-draft/sap1-1prd-exsumfigs.pdf
In summary, the US Climate Change Science Program tells us in November ’05 that all satellite and radiosonde measurements show a lower warming of the lower troposphere than of the surface, expect for the RSS satellites (but only when compared to HadCRUTv surface estimates): see figure 3. All surface estimates except HadCRUTv also show a rate of warming lower than 0.2 oC per decade for the 1979-2004 period. I find it amazing to find such discrepancies when jumping from one source to another in a field of science such as physics. I always thought that we economists were the experts in torturing data.
[Response: It looks to me like the wiki page is more up to date than that report. Sadly the page you give doesn’t give sources (unlike the wiki page) so its hard to be sure exactly which datasets they are using. You say “Of course I am in no position to discuss your or Wikipedia’s assertions” – which is nonsense: everything on that wiki page is carefully sourced, it can all be checked – William]
As for c), you must be right when you say that I’ve got the science wrong. I just do my best to keep up with a complex discussion out of my area of expertise. But on this particular piece of “science” I followed Christy and Michaels, who must have got it wrong too (sorry, no links available right now).
[Response: Well, provide the link and you might be more convincing. In the meantime, follow the links I provided… – William]
Re #143
“On the other side of the fence (and I am not implying that you fall into this category!!)”
Actually, feel free to call me a sceptic, if you want. But one that is willing to change his mind. I have nothing personal at stake in this discussion and, in fact, I’ve already changed my mind on certain things in this thread after reading Gavin’s first post.
My personal opinion about scientific biases is that ideology is a much more powerful source of bias than the scant economic corruption cases that there must also exist. But, as I said, this works both ways: for the left/interventionist/ecologist oriented and for the right wing/free-marketers. I gave quite an illustrative example of the former kind in my post #124. Then you also have the “ego factor”. Once a scientist opts to adhere to a side in a heated scientific debate, is he likely to give in unless overwhelmed by incontrovertible data? Given the nature of climate research, that kind of data is particularly difficult to produce, especially in the short or medium term.
I do not think that you need to posses a conspiratorial mind in order to find reasonable some scientists’ discrepancies with the majority of their colleagues. Do people who adhere to low-carb diets have conspiratorial minds? Do economist who still favour deficit-driven growth policies necessarily believe in conspiracies?
With all this said, I do confess that I find myself quite uncomfortable challenging the opinion of the majority of climate experts. But it shouldn’t be so difficult to disprove the sceptic scientists’ opinions, if they were nothing but fallacies, should it? And I don’t quite see that happening, sorry.
re 160. Mikel Marinelarena wrote … “In summary, the US Climate Change Science Program tells us” …
Mikel, a few questions…
Do you the name of the person directing the US Climate Change Science Program? Was it the same person as in Jan 2003? Excerpts from Jan 2003 public comments on a U.S. climate change plan follow. Do you know why it is than none of the public comments seem to have been used in the final plan that came out in the summer of 2003? How do the various plans relate to each other?
—
Public comment excerpts on draft U.S. Strategic Plan for the Climate Change Science Program (CCSP) – 18 Jan 2003
STATE OF CALIFORNIA
“The state of California takes climate change quite seriously. We are concerned about the potential costly impacts of climate change on water, energy, and other key economic and environmental systems in the state. In recent decades, for example, stream flow records show a trend toward earlier snowmelt in the principal water supply for the state, the snow pack for the state, the snow pack of the Sierra Nevada: a likely early manifestation of climate change. ” …
NOAA’s CLIMATE MONITORING AND DIAGNOSTICS LABORATORY (NOAA-CMDL)
“We need to make clear to all readers what is certain”. … “We know that major greenhouse gases are increasing in the atmosphere over the past century at rates higher than anytime in the historical record. We know that the increase in CO2 is related mostly to fossil fuel emissions. We know that a diverse group of global models cannot replicate the 20th century increase in temperature without involving the observed greenhouse gases.”
SIERRA CLUB (Craig)
“Human-forced global climate change is a problem of steadily growing importance that calls for responsible action now. There is so much momentum inherent in the several components of the Earth system that respond to greenhouse gas forcing, and so much momentum inherent in the socioeconomic system that is responsible for steadily increasing greenhouse gas emissions, that there is no room for the luxury of another decade of the scientific studies to finely tune response measures”
WYNDAM, CITIZEN
“This issue (global warming) has been studied to death. It is time to act. Stop stalling and start listening to scientific reports already compiled.”
OFFICE OF ATTORNEY GENERALS FOR MASSACHUSETTS, CONNECTICUT, MAINE, AND
NEW YORK “The Strategic Plan Emphasizes Research Efforts Geared Toward Adaptation Policies and Fails to Address Adequately the Immediate Need for Mitigation Policies, which Should Be Implemented Simultaneously with the Strategic Plan.” … “After decades of research and debate, there is now a clear consensus among scientists, which has been accepted by the United States, that climate change is occurring and that the combustion of fossil fuels by humans is the primary contributor. See e.g., U.S. Climate Action Report 2002, U.S. Dept. of State, Washington, D.C., May 2002 (“Climate Action Report”) at 5.” … “Most scientists also agree, as discussed in detail by the United States in the Climate Action Report, that global climate change will cause devastating, disruptive, and wide-ranging impacts to climate, ecosystems, and public health and welfare. Climate Action Report at 81, et seq., (Chapter 6). See also, Climate Change Science: An Analysis of Some Key Questions, National Research
Council (“NRC”), National Academy of Sciences (2001) (“NRC”2001″) at 18-21 (Chapter 6).” … “Regardless of what the specific, regional changes will be, and despite some potentially beneficial localized changes, it is beyond dispute that harmful environmental and climate changes will occur. Among the types of likely changes that the United States has projected are the loss of sensitive ecosystems such as barrier islands, altered agricultural patterns, increased droughts and flooding, and increased infectious and heat-related diseases and illnesses.”
CRISTINE CORWIN, BLUEWATER NETWORK
“Time is of the essence and it would be irresponsible to substitute
unnecessary research for implementation of commonsense solutions. If we
begin reducing our greenhouse gas emissions now, it will take a lot less time to stabilize the climate.” http://www.bluewaternetwork.org/
RAYMOND PIERREHUMBERT, THE UNIVERSITY OF CHICAGO
[Statement from the CCSP: “radiative balance and cloud structure from increased upper tropospheric water vapor is potentially quite large and could be positive or negative.” ] … “This statement is incorrect. The feedback from increased tropospheric water vapor is invariably positive.”
DAVID L. WAGGER, PH.D., SELF
“This is a misleading statement at best, especially if the intent is to
divert attention from CO2 as the main driver of anthropogenic climate
change. Unlike CO2, water has a short atmospheric lifetime, can coexist
in three phases, and has a highly variable atmospheric distribution.
While water vapor provides baseline greenhouse heating, CO2 and other
GHGs supply the perturbation driving climate change.”
MICHAEL MACCRAKEN, LLNL (RETIRED)
“There is really very little basis for thinking that the upper troposphere water feedback process could be negative, despite what Lindzen suggests. Were it negative, it would be very hard to have had an ice age (as it would have induced a warming influence to prevent it), we never could have had an ice ball Earth (as there would be to much water aloft), we could never have had Cretaceous warmth as the cooling effect would have countered that, plus the amount of water vapor in the upper troposphere increase from pole to equator (so from cold to warm conditions). The IPCC has reviewed studies of this and there is just very little reason to indicate it is possible, and it may well create important inconsistencies with past climates.
DAVID L. WAGGER, PH.D., SELF
Phrasing this as if there is an equal chance or positive versus negative is irresponsible. I think that there is a high level of certainty that: “While water vapor provides baseline greenhouse heating, CO2 and other GHGs supply the perturbation driving climate change.”
PATRICK NEUMAN
“All dewpoint and relative humidity data from historical records should be made available in digital format for modeling and analysis.” … ” Please, add: Temperature data by itself is inadequate in monitoring changes in climate. Changes in enthalpy (temperature, humidity, phase change – latent heat exchanges) are very important. It can be misleading to look only at temperature measurements without considering changes in humidity (dewpoints). Near surface humidity is very important in determining the rate of snowmelt, and ice thaw due to the latent heat exchange from the condensation of water vapor on cold surfaces.
“Increasingly warm conditions at the start of the Eocene caused the extinction of some prominent species of the prior epoch.” .. ” The forests that had housed numerous primate relatives were replaced with denser, often tropical, forests. Species either adapted to the new climate and environments or died out”. http://www.mnh.si.edu/anthro/humanorigins/faq/gt/cenozoic/paleocene.htm
CALIFORNIA AIR RESOURCES BOARD
“Land cover change is not only a product of direct human disturbance and modification, but may arise as a consequence of climate change. The
effects of changing seasonality of precipitation, temperature regimes, or disruption of hydrologic processes (e.g. the loss of perched soil water when permafrost melts) may have important effects on carbon uptake, biogenic emissions, dust, or other direct effects on the atmosphere in addition to potential changes in surface albedo.”
CALIFORNIA RESOURCES AGENCY
“While it is important to understand the past, it is not always a good
guide to the future. Increased globalization is likely to drive land use change in ways not easily predictable from past history. One could infer from language in several places in this chapter that globalization is a key driver but it deserves more explicit recognition.”
MCCLAIN, NASA
“Descriptions of the atmospheric and terrestrial knowledge, needs,
products, and payoffs are more detailed than for the oceans. However, it is thought that the oceans regulate about half of the CO2 uptake and
global primary production (some recent publications have reduced the
sequestration numbers). Therefore, the oceans role should be represented in a more balanced manner.”
JEFFREY GAFFNEY, ARGONNE NAT’L LABORATORY
“the carbon cycle includes the emissions of isoprene and monoterpene
hydrocarbons as well as a number of other trace gas species…” These
emissions are quite large and are now known to play a role in determining the atmospheric composition of the troposphere on regional and global scales. Indeed their presence in areas where there are anthropogenic emissions of air pollutants such as nitrogen oxides and sulfur dioxide, can lead to increased levels or regional ozone and fine aerosols that are important in radiative balance considerations”
>snip< Ozone is a potent plant phytotoxin. Increased tropospheric ozone (a greenhouse gas) levels will lead to the stomatal resistance being increased leading to reduced uptake of carbon dioxide, less water emitted through evapotranspiration, and less emission of volatile organic carbon (i.e. isoprene) from plants. Carbon sequestration under ozone exposures have been shown to reduce carbon uptake in FACE experiments even at moderate levels ...". "At 60 ppb levels carbon dioxide uptake even under high carbon dioxide exposure was reduced significantly due to this interaction. This type of feedback is not really addressed in this document." NED FORD, SIERRA CLUB "A reasonable estimate of the rate of ocean saturation suggests that by the end of this century under BAU, we will have effectively saturated the ocean. Further air/ocean transfer will occur, but it will require proportionally larger increases in atmospheric levels and much more time." NOAA/CMDL "What's missing is that climate change itself could significantly affect our predictions for the carbon cycle even if we understand carbon dynamics pretty well. CH4 is specifically mentioned here and Human Dimensions pops up." End of excerpts from public comments to a draft U.S. Strategic Plan CCSP 18 Jan 2003 ---
Re #s 153, 155, 158:
Many feel the need to debate the issue, as prescriptions for change affect their bottom line and delaying the change delays the costs associated with change and effects. I agree with Ferdi to a certain degree, but societies take a long time to turn, and the infrastructure we lay down now may affect our future actions and make it more difficult to adapt to a changed system. Therefore, the sooner we begin to plan, the lower the likelihood that our actions today will negatively affect our choices in the future.
As it is nearly impossible to forecast what will happen in the future (why it is better to plan with scenarios – ask the military or corporations), it is best to have a range of options available to us. The longer we fail to act, the more it is likely that our range of options will be limited.
Best,
D
Re #157 and “I must have an exceptional group of friends, family and acquaintances because not one has a considered opinion that AGW is proven to be the main reason for the current warming. The few that believe it is quite openly say that it must be so if the “experts” say so.”
Of the sample of your immediate circle, how many are professional climatologists or planetary astronomers? If the answer is “none,” why should I care what they think on this issue? Undemocratic as it may sound, every individual’s opinion does not have the same value on a scientific issue.
Re #164 Outch!
Since we are constantly told all “the experts” agree why is nothing happening? Why are we still jetting off to the sun and doing all the other carbon intensive things?
I am glad that in this country at least every citizen’s view counts equally when sitting on a jury or casting a vote regardless of whether the issue is scientific or not. Science is peppered with both with amateur breakthroughs and expert frauds and goofs.
But to answer the question a few.
Re #151
There may be changes in cloud cover during solar cycles that cause a variation in cloud effect of +/- 2W/m2 during a cycle but this doesn’t mean there will be similar changes over the long term between the same part of different cycles. What you need are cloud records from several cycles to determine how much cycle-independent cloud feedback there is.
Re #166:
Chris, you are right, one need several solar cycles, if possible of different amplitude, to see if the cloud changes follow the solar changes on longer term. Unfortunately, we have only (relative) accurate data for the last two cycles, thanks to satellites.
There still is discussion about the difference in TSI (total solar irradiation, see Fig. 1 in Scafetti and West) between those cycles. But if we assume that there is a slight increase, this should be visible in the cloud data as a decrease in cloud cover.
Indeed, if you have a look at Fig.1 of Kristjansson ea., there is a decrease of ~0.5% in low cloud cover from peak to peak and a decrease of ~1% in low cloud cover for the throughs. But the latter may have been influenced by the 1998 El Nino. And the change also can be a response to the general increase in ocean temperatures and/or longer term internal ocean cycles… As we are near a solar minimum, it may be interesting to compare the extended TSI and low cloud data up to now.
Re #162 Sorry Pat, I don’t have any answer for the questions you ask me about. But I’m under the impression that you may know what those answers are. If they help understand why the tropospheric temperatures (and to a lesser degree the surface ones) are not behaving as predicted, according to the source I gave, please let me know. In any case, people seem to have migrated to other topics, which unfortunately I don’t have the time to follow now. Perhaps they consider “the science to be settled” on this one.
re 168. Mikel,
Maybe I think I know the answer to some of them.
I’ve been making new photo plots on line showing that January 2006 was the warmest January of record (1890s-2006) for climate stations in eight or more states in the Midwest and Great Plains.
Re #160: Mikel, you need to read at least the entire executive summary. But, to briefly answer your question:
“In 2000 and 2001, the NRC and the IPCC both concluded that global-mean surface temperature increases were larger and differed significantly from temperature increases in the troposphere. The new and improved observed data sets and new model simulations that have been developed require modifications of these conclusions.”
“Either amplification effects on short and long time scales are controlled by different physical mechanisms, and models fail to capture such behavior; and/or remaining errors in some of the observed tropospheric data sets adversely affect their long-term temperature trends. The second explanation is judged more likely.”
In other words, the past data that disagreed with the models has been found to be incorrect. The arguably over-subtle wording is because the proprietors of the past erroneous data sets are co-authors of the report and so are eating some pretty major crow just now. Elsewhere in the report there is detailed discussion of exactly why it has been difficult to obtain consistent data from both satellites and radiosondes.
For a nice narrative (with citations) on the history of global warming skeptic/denialist/contrarian scientists (and a few non-scientists), see http://stephenschneider.stanford.edu/Climate/Climate_Science/CliSciFrameset.html .
Thanks Steve. I’ll try to read that article this weekend. But Stephen Schneider is one of the scientists that in 1976 was endorsing the global cooling scare, did you know that? Even William Connolley disaproved his quote in Lowell Ponte’s alarmist book ‘The Cooling’.
Still, the question remains: why, according to the very recent (11/05) US Climate Change Science Program draft, is the lower troposphere warming slower than the surface in almost all measurements? There must be some way of wording a simple explanation for this evident contradiction to the AGW theory.
This machine translated spam is hysterically funny, but I hope the linkspammer’s gone.
Like the comment above I also am extremely sceptical of the type of computer models being used for climate simulation. And yes models (visual, hydro and electronic) are my area of expertise!
For the types of models used (deterministic PDEs/ODEs/Parameterised/empiricals) it is a simple fact that perturbation of the initial and/or boundary conditions can drastically alter the outcome as can a multitude of other “element” assumptions i.e. amount of cloud cover, ground characteristics, ocean and wind currents, convection etc let alone such arcane things as inability to model “artefacts” like water dimers, weak bands, elevated state IR absorption etc etc etc. The list of assumptions and guesses that forms a foundation of the models is almost endless and yet it is known that only a small change can have a completely misleading convergence effect. Even stochastic approaches cannot resolve the unresolvable: subgrid-scale phenomena, and large-scale (chaotic) non-determinism both of which can, by themselves, drastically change outcomes.
The parallel with other models may be relevant. When electrical models first started the numerical approach was fine for frequencies up until about 100kHz. As our understanding of the physics improved so did the “approximations” of real elements (aka models) and the useful frequencies now extend into the GHz area. However we know several things:
1: that after certain frequencies the “theory” diverges wildly from reality
2: even within the known limits and with very well defined models we routinely get “bitten” by all sorts of small anomalies
3: these “small” anomalies have wildly convergent or divergent effects on predictions
Unfortunately we cannot do experiments with the climate and we only have one set of data and starting conditions to align to. The early climate models needed all sorts of “fudges” to push them to correlate with observed data and not to go into runaway. In other words the models have been refined with many “uncertain” effects to force them into alignment with the last 100 years (which are, as the IPCC report stated: “… of the same magnitude as natural climate variability”).
In particular the failure of current mainstream models (e.g. GISS) to align with some near and far historical data is not explained e.g.
1: Violent but short lived changes of up to 15C in a few decades!
2: Recent history, 1400/1700 – the 1940-70 cooling and even the current winter in northern hemisphere
3: Not so recent history when CO2 was 5-10 times higher than present (1000-1500ppm)
4: During some cooling periods CO2 actually rose (eg Miocene period).
5: Misalignment of “uncertain” effects and observed climate (e.g. southern versus northern aerosols) etc
6: Misalignment of surface, tropo and other recent temps including lower than predicted increases.
However, it is the “doomsday” predictions of these models which are now being used!
I note in passing that other types of models provide a quite different outcome; which model is the best and which outcome is correct?
Even the subject of measuring temperatures and the “fudging” required to correct for urban effects; cities (i.e. proliferation of traffic and air conditioners), “heat islands”, biases in surface versus sea temperatures and northern (versus southern) are just a few items of concern. Even as late as last year satellite data (which I had considered to be most reliable) was found to be flawed. Contrary to the statements by Gavin et al above not all of the concerns have been addressed by any means! For instance we know that many isolated temperature curves (surface and sonde) do not follow the overall trend. How can this be?
Penultimately some scientists have forgone the “truth” principle to ride the climate juggernaut for more research funds. According to one American climatologist, the “scare-them-to-death” approach seems to be the best way to get money for climate studies. Dr. Stephen Schneider, a leading prophet of manmade climate warming (and previously cooling!), stated this bluntly:
“To capture the public imagination… we have to… make simplified dramatic statements, and little mention of any doubts one might have…. Each of us has to decide the right balance between being effective and being honest”.
Add to this mix extremist politicians who have found GHGs so convenient for their anti-technology, anti-corporate anti-everything agenda.
Is there any wonder that some, including many scientists, are sceptical of the “predictions”.
To discard these criticisms arbitrarily or to treat intelligent scepticism with ridicule will only detract from any case made.
Having said that I would like to pose some questions and comments to those who know more than I do about this issue.
1: The statements about CO2 and its link to global temperatures have some serious problems.
Although it seems clear to me that, barring some hidden source of CO2 (i.e. the Siberian peat bogs or the recent discovery that plants produce large amounts of methane!), the increase in atmospheric CO2 is probably mainly due to anthropogenic sources.
However, if CO2 is so intrinsically linked to temperature how is it possible that, with no other observable geological events (meteor, volcano, tilt etc) CO2 can increase during a cooling period as has been observed in the geological record?
It is not possible for the relationship between CO2 and temperature to be as fixed as the models assume: either the geological record is incorrect or the models are wrong!
2: Different models produce different results! The outcome from solving all the ODEs/PDEs etc. varies with the methods used. Some of the models predict cooling events, why are the only models propagated those which predict “boil in oil” scenarios?
3: For the last 10,000 years the climate has been relatively “quiet” but previous to this climate change has been generally violent and abrupt. Changes of +/- 5C per decade have been commonly recorded throughout the geological record. These changes were not isolated in small areas but were global in nature. Again there are no geological reasons for these abrupt variations. What caused them? Unless the models align with these known events then any future predictions based on the models are as equally invalid as their ability to correlate with the past!
4: Even in our recent past events like the Little Ice Age, multiple glacial advances and retreats have no apparent causes and were not accompanied by commensurate CO2 changes? There appears to be no rational explanation for these relatively violent events and they do not appear to be forced by CO2 changes as the models predict?
5: The table used to indicate the relative contribution of GHGs in Real Climate is useless.
To anyone involved in computer modelling and numerical analysis the statements:
“This isn’t a perfect calculation but it’s quick and easy and is close enough to the right answer for our purposes”
and
“but that is complicated for clouds, O3 and Aerosols which have impacts on solar radiation as well as the long wave, so I only give that value for the ‘pure’ greenhouse gases”
are extraordinarily worrying!
Further the relationship between absorption curves is very complicated. This is different for each molecule and each environment. The table would have been more useful if the “change” corresponded in magnitude to the observed changes in the atmosphere rather than complete removal and was backed by empirical evidence.
These simplistic models for the absorption of just one of the molecules alone (water vapour) are, with all due respect, rubbish! See for example http://physicsweb.org/articles/world/16/5/7/1
As a last indicator we know of geological times when the CO2 was up to 10 times its current level and the temperature was only a few C above what it is now. Plug that into GISS and all biological life would have been extinquished! Again either the model is wrong or the geological record is wrong!
Accordingly as an indication of “contribution” at atmospheric levels of absorption the table is effectively useless and should not be used for any indication of the whole or part of the contribution of ANY of the GHGs other than to order of magnitude levels. Please stop using it!
6: The estimate of the warming effect for a doubling of CO2 (3 +/-1C) is also not supported by the geological record. CO2 levels have correlated with temperature only ~50% of the time of large climate changes and in many cases followed not led temperature changes. However there are numerous places in the record where CO2 fell during warming periods or rose during cooling (e.g. Miocene). Again this implied fixed relationship is not supported by the geological record.
7: The “human” induced changes in methane are now in serious question after the recent German research about plants and methane! So the statement “something like double that” regarding the effect of the other GHGs becomes unsubstantiated!
And before the personal stuff starts:
1: Yes it seems the planet is getting warmer, about 0.5 – 0.7C in the last 150 years. However this is well with normal limits and is actually quite a mild change by geological standards
2: Yes CO2 is a greenhouse gas and we have increased its concentration in the atmosphere.
3: Yes some part of the warming is probably due to anthropogenic causes.
4: Could the computer models be correct? Yes with about the same probability they could be wrong!
The models are far too simplistic to even come close to modelling the climate, not in the least because they do not even give a reasonable approximation of modelling the “effective” absorption profiles of the three most prominent GHGs in the atmosphere: Clouds, H2O and CO2 let alone all the complexities of the other elements involved.
5: Yes I do believe that we should be using less fossil fuels For all sorts of reasons not least is that they are a precious and irreplaceable resource.
6: At the current rate of warming the countries worst affected by sea level thermal expansion (Asia) will be flooded by the tectonic plate subsidence and tsunamis long before that caused by warming! This is an example of the alarmist scaremongering crap that pervades this debate in the popular media.
Prof Jon Jenkins
[Response: Well, Professor Jenkins, where to start? You have listed a litany of problems, none of which have specific enough criticisms to properly rebut or discuss, but which show much evidence of having been picked up second or third hand. Much of your critique has no obvious basis – rapid global temperature changes of +/- 5C? the expectation that climate models should be able to produce seasonal weather forecasts? Standard out of context mis-quotes of Stephen Schnneider? – that I am not inclined to pursue this discussion. However, you specifically criticise my post on water vapour, and declare it ‘extraordiniarily worrying’ – Quite frankly, I’m flummoxed. Back of the envelope approximations are used throughout physics to illustrate various points and orders of magnitude of different effects and this is exactly the tack taken here. If you would care to point out a more careful analysis, I would cheerfully acknowledge it. But, your implicit claim that I must be fundamentally wrong simply because you don’t understand the concept the radiative forcing seems a little presumptious. I therefore invite you to focus on your criticism point 5, and explain to me (with references please) why you are so worried. A little work with a line-by-line radiative transfer code, integrated over the planet and over the seasonal cycle should provide you with a more correct answer, and if my numbers were out by more than a few percent, I will post your analysis here and link to it from my own. Of course, you may prefer to randomly fling criticisms around as above and never choose to make a substantive point. I await your response. – gavin]
Prof. Jenkins, the page you point us to says they too are relying on “crude calculations” — did you look for followup info from the actual researchers being described as saying this, to see if they supported their back-of-envelope calculation later?
Quoting from the article:
“… Water vapour in the atmosphere can change phase, which leads to more clouds, and greater cloud cover means that more sunlight is reflected straight out of the atmosphere. Crude calculations suggest that the two effects approximately balance each other, and that water vapour does not have a strong feedback mechanism in the Earth’s climate.
We have tried to outline some of the unresolved issues concerning water in the atmosphere. …”
That was May 2003. PhysicsWeb isn’t sensationalist but this was journalism; did they get anywhere with the refereed journals, substantiating this?
Jon Jenkins #173
You’ve really opted for quantity over quality here, I must say. It makes it hard to know where to begin and how to approach your post. So I am just going to pick and choose a few things, perhaps you will surprise me and provide something concrete to focus on.
Regarding “the failure of current mainstream models”
I’m sorry, but you really need to provide some references for this. What are you talking about?
– I havn’t seen model runs over 1400/1700, where can I see that?
– The mid century cooling is well reproduced, see here:
http://www.grida.no/climate/ipcc_tar/wg1/figspm-4.htm
– The current NH winter is weather, don’t look to a climate model for weather forecasts.
You presented some “questions”:
What statements have what problems?
The CO2 can be conclusively attributed to fossil fuel burning due to the isotope signatures of the C and O atoms. That recent study you mentioned does not say that plants only started producing methane in the last 150 years or so. We are observing a change in atmospheric composition, the explanation must be something that has changed. The Siberian peat bogs melting is a result of anthropogenic warming, ie our CO2 came first, if the bogs starts to produce their own CO2, that is called a feedback mechanism.
The correlation of CO2 levels and temperature is not an assumption of the models, it is an output! It is also an observation, both over the last century and over the last almost 1 million years in the glacial records.
http://www.grida.no/climate/ipcc_tar/wg1/fig2-22.htm
Other geological periods had other major differences and offer considerably less data. It would be nice to have perfect understanding of every point in geological time but, a) it is unlikely we ever will and b) let’s start with today where we can measure most of what we can think of.
References please? What models predict cooling?
References please? I hope you are not so uninformed that you are talking about the glacial interglacial cycles, those swings took thousands to tens of thousands of years. Probably not, so what are you talking about?
Isn’t it a little alarmist to characterize the ~.5oC over ~300 years that was the LIA as a violent event (and it was not even globally synchronized)? Really, who are you kidding? And please provide some references for some “violent” glacial retreats and advances in the last few hundred years, or whenever you wish.
Sorry, it is not human emissions that are now in serious question, it is the natural methane budget that needs to be re-examined. I think you are confusing “just discovered” with “just began” or something. Whatever it is that the plants are doing that we only just noticed, I think the default assumption must be that they have done it all along despite us not being aware.
I do hope you will offer up some support for at least a few of the bullets in your machine-gun of a posting, it is not fair to ask people to argue against or explain away something you have not clearly described.
It is interesting how quickly these responses get personal so quickly and
even more interesting the failure to acknowledge valid criticisms. It is often a sign of belief versus fact in a debate!
I am not going to write a thesis on this issue nor will I quote tomes on
geology but I will respond to several issues raised
Gavin’s comments
Read the full GRIP report. I quote a relevant phrases here:
It is well known that during exit from the last Ice Age for example that sea levels and temperature rose at about 10 times their current rate. This was NOT preceded by CO2 rises I might add and evidence can be found in any standard geological text.
These and a myriad of geological facts are present in the literature. However many in the current debate seem to choose to conveniently ignore the geological history of earth. I make the simple statement again: either the climate models are wrong or the geological history is wrong!
The discussion of climate versus weather is superfluous. The fact is that, barring a perturbating geological event (i.e. in steady state) the models do not and cannot predict a cooling on any large scale: they predict inexorable warming! IF the “weather” in the Northern Hemisphere becomes climate or if we show any cooling trend then the models are wrong! Fudging with aerosols to “cool” the models predictions in the Northern Hemisphere should have also predicted faster rises in the southern hemisphere (less soot etc). Oopps, wrong again, lets go looking for another fudge!
This was not quoted out of context at all. It clearly indicates a willingness
to “embellish” the public record. The fact is that some scientists have become
Pavlov’s Dogs for research funds handed out by politicians (I know because I am
both!).
As long as the results are viewed as “order of magnitude” and not as
conclusive proof then this may be acceptable, and I stress may. However the
table was then used to “prove” your hypothesis. I contend that the proof would
have required more than “order of magnitude” accuracy. Simply correcting for the
sum errors is wrong, it took no account of either the chemistry or structure of
the atmosphere and the simple fact is if we redo your analysis with a factor of
10, as you suggest, your theory falls over. Unfortunately there is no “more
careful analysis” as you suggest which is exactly my point.
The point was exactly as you put it: “back of the envelope” calculations are
NOT science. It is only in the recent past that this has become accepted as
science. To use what is effectively guesswork based on mathematic models we know
are defective, using deterministic solutions we know are “fragile” (particularly
in ill-defined systems) and based on theory we know is either incomplete or only
approximate to affect billions of people and funnel trillions of dollars is
ludicrous! The very fact that there is no evidence either way does not make a
theory correct by default!
[Response: Well, I thought this is what you were referring to. However, you make a serious error in extrapolating a temperature change in Greenland to a ‘global’ change. The changes in Greenland are most probably related to changes in the North Atlantic circulation and are comparable to the changes seen in ‘shutdown’ experiments done with all of the different models (see Stouffer et al, 2005; Vellinga and Wood, 2001; Rind et al 2001). There are correlations of these events around the region, and as far away as East Asia (Yang et al, 2004) and Santa Barbara Basin in the Pacific (Kennett et al), however the temperature changes are much smaller the further away you get from Greenland. A ‘5 C’ global change is completely unsupportable. Remember that the full glacial to interglacial change (which took around 10,000 years) was only around 5 or 6 deg C. Next point. CO2 in glacial-to-interglacial change is of course a feedback to the changes in orbital forcing and is known to lag the temperature – however the GHG forcing (CO2, methane and N2O) ends up providing almost half the forcing of the total change. So a feedback, but an important one. (see our previous post on this).
Contrary to your next assertion, the difference between weather and climate is fundamental, not superfluous. I presume that you are familiar with the concept of initial value problems (weather) with boundary value problems (climate), and in chaotic systems the difference between an individual path (weather) and the manifold on which all paths lie (climate). Models do not produce ‘inexorable’ warming – they produce cooling as a function of volcanic eruptions (as observed), changes in orbital forcing (as observed), from 1940-1970 (as observed), at the LGM (as observed). With no changes in forcings, they show interannual variability of a similar magnitude as seen in the data, both warming and cooling.
If you are not able to find the full Schneider quote, I suggest you simply look at a previous rebuttal and the full quotation here.
And finally, your criticism of my estimates of the long wave absorbtion in the atmosphere (which I claim are good to a few percent, not an order of magnitude) appears to based on nothing at all. If you cannot point to a better estimate that is substantially different, while my analysis is a very good match to a completely indpendent study done almost 20 years ago (Ramanathan and Coakley, 1978), it seems odd that you have concluded it must be wrong.
As you might suggest to one of your own students who brings in a piece of work that relies too heavily on secondary sources, I suggest you avail yourself of your no-doubt well equipped university library to actually read some primary sources prior to your next reply. The IPCC TAR report has almost all the references you will need. I will leave it to the other commenters to deal with your other mis-conceptions. By the way, if you are actually interested in a serious discussion, I suggest that you focus your efforts on one particular topic at a time. -gavin]
Hanks Comments
Hank I could not have put it better myself:
I state again:
Back of the envelope “crude calculations” are NOT science. It is only in the
recent past that this has become accepted as science. To use what is effectively
guesswork based on mathematic models we know are defective, using deterministic
solutions we know are “fragile” (particularly in ill-defined systems) and based
on theory we know is either incomplete or only approximate to affect billions of
people and funnel trillions of dollars is ludicrous!
Do I have a better theory? No. But does that mean I accept what I can clearly
see to be defective models as being the final solution which should drive the
policy of the western world? Absolutely NOT!
The point is exactly as it is to Gavin: we should not be basing global energy
policy and spending on little better than guesswork! What we need is hard
SCIENCE of which there is little and the press, politicians and eco warrior
scientists are much to blame.
Coby’s Comments
See the GRIP report mentioned above, actually it was part typo but the cores
both in Greenland and Atlantic clearly showed 5C/decade magnitude. Many basic
geological texts also relate temperature and sea changes up to 10 times the
current rates across the globe. Goodness it is even in the IPCC report:
“On the other hand, very rapid warming at the start of the Bolling-Allerod period (14.5 to 13ky BP), or at the end of the Younger Dryas (12.7 to 11.5ky BP) may have occurred at rates as large as 10°C/50 years for a significant part of the Northern Hemisphere“.
“The warming phase, that took place about 11,500 years ago, at the end of the Younger Dryas was also very abrupt and central Greenland temperatures increased by 7°C or more in a few decades“.
I am not sure where this was but a both a Canadian and British university ran
simulations of the mid millennia period using estimations of solar irradiance and
gases from fossils and trees. It was published on web sites and I will have dig
it up. I do not keep all this stuff at fingertip but the correlation was not
good with CO2 and much better for solar irradiance. This was a few years ago and
I have not seen any more simulations since. Not unexpected in the current
climate (to use a pun) that groups publish “unpopular” results. This has been
the other downside to the current debate: any scientist that publishes
controversial findings is castigated not only by some of his “eco warrior” peers
but especially by the “anti-everything” political agenda and popular press. I
know colleagues who work for CSIRO Climate in Australia who are literally
fearful of uttering anything which contradicts the “corporate spin” designed to
win research funds, in fact they are officially gagged from speaking.
The models I have seen vary considerably on their correlation for the 1940-70
period. The IPCC picked the best model however I might add this process of
“tweak” the model till we get correlation and then accept that the model is
correct is not science and flies in the face of all we know about these types of
models. Again I quote from the IPCC report itself:
The model should basically be in correlation for all spatial and temporal
regions. If it is not then the model is wrong and its predictions are wrong. The
question – can the successful simulation shown in the figure be used to support
the proposition that changes in CO2 levels (presumed to be due to
fossil fuel burning) are causing the observed temperature rises over the past
century? To which there is only one answer: ONLY if no other model
assumptions can replicate the observed behaviour, and also if the model can be
applied successfully to data from the more distant past, when much greater
ranges in temperature change have been inferred.
As I said above: barring some “event” the models will not accommodate a “cold
winter” and there has been no event! The arbitrary nature of when weather
becomes climate makes the decision difficult but it is irrelevant: according to
the models we can’t get cooler in steady state!
The assumption that CO2 drives temperature. Even the IPCC report touched on
the phase relationship raised by Fischer but then simply refused to consider any
of the latter work by others. The evidence points more and more to a lag
relationship not a leading one!
The isotope data indicate that contributions to the atmosphere come from
“old” sources but I do not just blindly follow the “plants preference for
C12/C13” and has been constant throughout time. As I said below in the
original post it seems probable on both logical and available science that this
is so. Unlike many I do not just accept “popular” or “consensus” as being
science fact.
No, this is factually incorrect! The relationship is not fixed at all. The
relationship should hold for ALL periods and this is not the case and very clear
examples exist both in the recent and far past where the relationship is not
explained by the theory.
Exactly and no! If the models do not correlate with what we know then the
models are wrong!
I will have to dig these up but both deterministic and other theory (chaos)
etc predict cooling during the first half of C21. The IPPC references some
of these but will have to get back!
See above, these are overtly evident
Again see above for 5C/decade changes
The assumption (and there are far too many in this debate already) had been
that the increase in methane for the last 150 years was totally anthropogenic
and it is probably wrong!
The change (not as abrupt) was also recorded in Pacific corals at ~ the same
time. This was a global change which occurred over a few short years and was
more intense in Northern latitudes. As far as the geological record shows there
was no “forcing” event to cause this.
Over a decade yes I agree but vast and large sections of the planet did
undergo such changes. And although the average global change was ~6C there is
ample evidence that this average was achieved by rapid global oscillations within decade periods. The current warming is entirely consistent with
that record.
No one of any sense is arguing that CO2 is not a forcing element of
importance. But the weighting of other forcing is debateable. We know that the
Solar Irradiance is also the highest it has been for at least 400 years.
Intimately, which is why I am sceptical!
As I clearly said, “barring a perturbating geological event (i.e. in steady
state) the models do not and cannot predict a cooling on any large scale: they
predict inexorable warming”. This still stands. We have had no major eruptions,
no major TSI events, no major GHG changes => we must see a continuing pattern of
warming EVEN over yearly scales. IF we don’t the models are wrong!
Regardless of what Schneider quote I have seen this so many times to know
that it is now common practice. It is particularly rife in the life sciences
such as Biology and Ecology where the “noble cause” has become more important
than truth and consensus has become fact.
Firstly you used the term “order of magnitude”. Gavin, you misunderstand my
criticism! Even a cursory reading of the literature tells a simple story:
evaluating the absorbtion profiles of even a single species of GHG in a lab is a
“hard” problem, doing it in the atmosphere with all its added chemical and
physical issues is even “harder”. Even when using the most sophisticated models
and the latest profiles (eg HITRAN) there are significant differences between
theory and reality in clear skies. In cloud the theories and models are
basically useless! To say otherwise is deceptive. I am sure you know this
research better than I do. The absorbtion anomaly is still an unresolved issue
as is cloud behaviour and trace chemistry even more so.
The result, as far as I am concerned, is that anyone who claims to be able to
work out the contributions to “few percent” is just having themselves on and I
think every atmospheric chemist in the world would agree. This may change as we
better understand the underlying quantum physics involved and can estimate the
intensities better but for the moment everything I have read tells me that we
just don’t know enough to make good decisions.
However, even if we accept the few percent in the climate models it is even
these “few percent” which determine the difference between the next glaciation
or molten lead! Again I, and many others, will not support decisions of such
import when they are based on such evidence
> Hanks Comments
> Hank I could not have put it better myself: …
Uh, really, you should be able to do better yourself, that was my point.
You could look up the people quoted, using the links in the news item you pointed us to, and see if they ever published that idea in a journal.
You can do better.
Re Jon Jenkins,
You claimed:
“Violent but short lived changes of up to 15C in a few decades”
and
“Changes of +/- 5C per decade have been commonly recorded throughout the geological record. These changes were not isolated in small areas but were global in nature”
and as support you offer a quote about GRIPS “Especially astonishing are the very short times needed for major warmings. A temperature increase of 5oC can occur in a few decades”
In short you claimed global changes of 5oC and even 15oC and to support it provide evidence of regional changes of 5oC over several decades. 15oC/decade global is not equivalent to ~2oC/decade regional. Now you did back away a little claiming a typo (I assume about 15oC) and acknowledging that the evidence you offered is for Greenland and N Atlantic, but in the very next breath you claim “Many basic geological texts also relate temperature and sea changes up to 10 times the current rates across the globe” and then quote again IPCC references to strictly regional changes. So back to square one, hand waves and unsubstantiated claims.
Sea level, sure, that’s a part of glacial melting, but temperature? Sorry, but no. The temp rises out of the deep glacial periods were about two decimal orders of magnitude slower than the current .2oC/decade. Please see here:
http://www.brighton73.freeserve.co.uk/gw/paleo/20000yrfig.htm
It is quite true that we do not have the resolution to conclusively show there were no decadal trends that were short lived but as steep or steeper than the last thirty years, much less global in nature, but neither is there anything in that record to support your contention above. Even if we take you to mean .8oC per century current trend, your claim would be 8oC/century, which puts the whole shebang in about one century when in fact it took ~7000 years.
You say right after this fallacious point that many in the debate ignore geological history. Well you have not cited any with any accuracy.
CO2 driving temperature is not an assumption, it is a theory. It is a theory that is consistent with all available evidence and consistent with the laws of physics and basic chemistry of gasses. This does not mean CO2 is the only driver, it does not mean CO2 is always the predominant driver. The lag between temperature and CO2 in the glacial record shows that CO2 changes are not only a cause of climate change, but they are a result of climate change. There is nothing hidden about that record, and nothing that contradicts current theory, in fact that evidence taken in totality is further confirmation that CO2 is strong climate forcing agent.
Since you value lessons from the geological record, you should consider the PETM event.
Again about the distant past in response to my pointing out that we just don’t know enough you said “If the models do not correlate with what we know then the models are wrong!”. What you are demanding is that the models correlate with what we don’t know. You claim models are no good if you have to use “fudge factors” (without identifying what models, what factors I might note) and now you want the models to reproduce the distant past with no data. Ludicrous!
Since it comes up several more times in your post, I wish to state again for the record that you have yet to provide evidence for global changes in temperature of 5oC/decade. The only non-hand waves you offered are regional indicators, and they are jumps that don’t show up in the antarctic ice cores I might add.
Your wisecrack about assumptions is highly ironic. Not just because of so many in your post but because you follow it with two whoppers. We have recently discovered that plants unexpectedly emit methane. Now you assume that this started 150 years ago, and you further assume the issue of attribution is settled. Try this post:
https://www.realclimate.org/index.php?p=236
Yes there was a typo it should have been 5C not 15! There is ample evidence in the ice cores, Altalntic sediments, corals and sea level changes (induced by thermal expansion not melting!). if you choose to igniore them so be it.
But it brings up the real issue about temperatures and time. Yes out of the last ice age the AVERAGE temperature rise over 10,000 years was 6C/10,000 = .06/100. However the geological record clearly shows that at the fine scale the temperature oscillated up and down several C over hundreds and even several C per decade, more than it has over the last 100! Some of these changes were regionally more intense but there is ample evidence for global involvement as mentioned above. This is exactly as you would expect for TSI induced changes.
This is the point: some are comparing an average over the last 100 years with an everage over 10,000! When we do compare apples to apples i.e. regional short term averages OR long term trends we find the current trend is nothing extraordinary!
Jon Jenkins states:
“there is ample evidence for global involvement” of “even several C per decade”.
Care to give us a reference?
John Jenkins wrote:
“but for the moment everything I have read tells me that we just don’t know enough to make good decisions”
Agree absolutely. Putting 10GT of carbon into the atmosphere every year without knowing the consequences is not a good decision.
Re Dr. Jenkins — another point is his statement about models with slightly different initial conditions diverging wildly. In my experience, radiative-convective models of planetary atmospheres converge, not diverge. You can start with radically different profiles of temperature versus height (I have!) and get pretty much the same results. This is exactly the opposite of what is claimed.
Yes, I know about the difference between RCMs and GCMs. My comment stands, I think. Gavin?
In comment #180, Jon Jenkins wrote … “However the geological record clearly shows that at the fine scale the temperature oscillated up and down several C over hundreds and even several C per decade, more than it has over the last 100!” …
But to me, it is no mystery that temperatures oscillate more in dry air than in humid air. Globally more humid conditions are a signature of a globally greenhouse warmed climate. Cold dry air was prevalent over large areas of the world during the Pleistocene, and most of the Holocene up to the 20th century.
The extremely dry air of the 1930s didn’t happen in the 1990s to current, and likely won’t happen again for millions of years. (See daily high and low temperatures for Jun-Aug of 1936 compared to Jun-Aug 2005, for Park Rapids, Minnesota, at:
http://madison.indymedia.org/newswire/display/28762/index.php
The gap between daily highs and lows in 2005 is much narrowed than in 1936. 1936 record high daily temperatures were a result of bone dry air and clear skies. http://climate.umn.edu/doc/twin_cities/mspdewpoint.htm
2005 summer highs and high lows were influenced by heavy greenhouse gas accumulations in the atmosphere.
103 Years of Twin Cities Dew Point Temperature Records: http://climate.umn.edu/doc/twin_cities/mspdewpoint.htm
How do you explain record heat and very low humidity from 1927-1936? I explained that in earlier comments in the article posted at Madison IMC. http://madison.indymedia.org/newswire/display/28762/index.php
To view additional 100 year temperature plots in the Upper Midwest, Great Plains, Northwest and Alaska see:
http://pg.photos.yahoo.com/ph/patneuman2000/my_photos
The requests for sources are the opposite of ‘personal’ — I ask what your sources are because I mistrust the appeal to personal authority.
I ask for your references because I assume you get your certainty somewhere. No individual could be an expert in all the areas you make statements about.
So where do you find the facts you rely on and are telling us here?
You sound very sure that you have everything right, that you are in the mainstream repeating things you take for granted everyone knows.
Often people who sound that way are indeed experts. What distinguishes them is, they can footnote. They know where their facts come from, and can give us cites to look up.
Experts understand there are questions of misreading, of interpretation, of using outdated sources, and of simple biased reading. We can check one another, as non-experts, by reading the same primary sources.
If you are not telling us your own personal research results, give us your published sources.
There are two ways to try to tell a convincing-sounding ranter from an expert in the field, for those of us outside the field — see if they footnote, and read the references with others and discuss the sources.
I’m just a reader here looking for some light on the subject.
This is the final post on this topic.
On Computer Models
The theory of the methods used in the GISS style models is reasonably well understood as is their limitations. When the models are reasonable within the boundary/proxy conditions and all the input/outputs are defined the system will probably behave. However this is not the case with climate, significant spectral uncertainties, absorbtion anomalies, chaotic systems, sub grid phenomena, uncertainties in initial conditions etc etc mean that at best the models are an interesting guide. If we tried to design other PDE/ODE/parametric systems (aerodynamics, fluids, electronics etc) with uncertainties like this we would be laughed at and justifiably so.
Burger and Cubasch have recently published some interesting analysis of the various models and on Mann’s recent publications which clearly demonstrate the problems of these models both in theory and practice of alignment to observed data and statistics. I would highly recommend that interested readers obtain and read.
For anyone to say that we should accept the current models as being representative or even close to reality and as a result to influence the spending of trillions of dollars and affect billions of lives, at this point in time, is indicative of other agendas not good science. This may/will change as better models evolve and more computing power comes on line and smaller grids are achievable.
Nothing said above has challenged this conclusion.
[Response: Random criticisms of admittedly imperfect models contribute nothing to the debate. Chaos, uncertainty in intitial conditions etc. are inevitable features of climate modelling and techniques have been developed to deal with these (ensembles, equilibirium runs etc.) and do not contribute as much to the uncertainty than is implicitly claimed here. You need to make a specific criticism and back it up if you want to be taken seriously. -gavin]
On Climate History
The climate history is clear in that oscillations of several C occur regularly on both hemispherical and global scales and in decadal periods. This is clear from ice cores (Vostok, GRIP, EPICA Dome C and numerous others), corals, sediments and other records in numerous publications on the web and in basic geological and palaeontology texts. The current warming trend when compared to the geological record (e.g. Greenland, MIS-11 etc), over the relevant timescales, shows nothing unusual and if previous similar warm periods (MIS-11, 13, 15 etc) are a guide may last for another 10,000 years!
Nothing said above has changed this conclusion
[Response: You are just wrong. D/O events in Greenland did not lead to global changes of ‘several deg C’ – they do not even appear in the Antarctica core temperature proxies for instance. Comparing the current warming period with previous stable interglacial periods is just bizarre. In the absence of any human interference, the Holocene may be expected to last 30,000 or even 50,000 years (Loutre and Berger, 2001) similar to MIS 11, but the warming from increasing GHGs is a significant extra effect. -gavin]
[Response: Just to nit-pick a bit: they do just about appear in the Antarctic cores, but are only really visible in retrospect now people know to look for them. Also, they don’t really show up in “geological” things well, not properly resolved – William]
On the Role of CO2
It appears that the increase in CO2 is at least mainly due to anthropogenic causes although there are still some niggling uncertainties such as how much the “naturally” increased CO2 (from the oceans, bogs etc) is contributing. It seems logical to me that some of the current warming is therefore anthropogenic.
However the models “predict” that CO2 increase leads inexorably to significant T increases but cannot explain why CO2 levels >1500ppm did not result in catastrophic temperatures whereas of course temperatures were much the same as today during that period. Further we know of periods when the temperature and CO2 were completely out of phase.
Predictions (by what I consider to be primitive computer models) that CO2 reaching levels of +400ppm will be catastrophic are simply not supported by the geological record!
Nothing said above has changed this conclusion
[Response: CO2 levels from before the period covered by the ice core records are highly uncertain, although reasonable evidence exists for high GHG amounts in warm periods like the mid-Cretaceous and Eocene. However, over geologic time changing continental configurations, volcanic impacts, asteriods, mountain formation, solar evolution etc. all have important climate impacts. In the period when we have reasonable data, say the last 400,000 years, there is plenty of evidence of CO2 impact on climate (Lorius et al, 1991). And finally, setting up strawmen arguments that models predict ‘catastrophic’ impacts from 400 ppm CO2 is a waste of time. Read the recent guest post on ‘Can 2C warming be avoided‘ to understand what is actually being claimed, and why some people feel that an increase of another degree or C increases the chances of ‘dangerous’ climate change. I would point out that the geologic record provides no examples (none!) of CO2 levels as high as today with a Greenland ice sheet and sea levels as low as today. The last time CO2 may have been as high as this (mid Pliocene ~ 3 million years ago), sea levels were 20m higher. Even stage 5e, which may have temperatures comparable to projections for mid-century, had sea levels higher by 5 or 6 meters. -gavin]
Re 182 “Putting 10GT of carbon into the atmosphere every year without knowing the consequences is not a good decision.”
Sounds like an intelligent remark. But the fact remains that curbing trace GHG emissions in the manners you AGW-adherents propose (manners of a distinct old flavour, not any different really from the ones Anthropogenic Global Cooling adherents used to demand) will cause less economic growth and consequently more unemployment. In fact, a great number of countries are ALREADY implementing some of those policies. For the most part, we will never know the names or see the faces of the people who will not get a job, lose the one they have or fail to escape poverty as a result of a lower global economic growth caused by the decisions you propose. But if you were to meet some of these people, would you be able to convince them that our current scientific knowledge demanded their sacrifice?
The “we can’t do it” people are really just the “we don’t want to” people and when necessity finally forces the issue, technology and innovation and policy will find the solutions simply because they must. I think the “mitigate climate change or keep prospering” false dichotomy debate could use a couple of healthy lessons from history:
1. In 1970, the U.S. Clean Air Act Amendments required 90 percent reductions in three types of pollutants from automobiles by 1976. Despite opposition to the 1970 Amendments, a technology that allowed the regulations to be met, the catalytic converter, was invented by 1975. The invention not only decreased pollution but also gave U.S. industry patents. Neither the economy nor the automobile industry suffered due to the 1970 regulations.
2. Thomas Midgley, the inventor of leaded gasoline and chlorofluorocarbons stated, in April, 1925, that the use of lead was “…of vital importance to the continued economic use by the general public of all automotive equipment, and unless a grave and inescapable hazard exists in the manufacture of tetraethyl lead, its abandonment cannot be justified.” Midgley himself developed antiknock alternatives to leaded gasoline, but he never needed to exploit these technologies, because lead was never regulated during his lifetime. When lead was first regulated in the U.S. in 1976, non-lead antiknock technologies were improved. Cars were immediately affordable while running without knock or lead, proving Midgley incorrect.
[note: the above two edited excerpts stolen from here: http://www.stanford.edu/group/efmh/bush/ ]
(any other apropos examples out there? I’m sure the same economic catastrophy was predicted as a consequence of protecting the ozone layer, would like to see some quotes or details)
“Neither the economy nor the automobile industry suffered due to the 1970 regulations”
This assertion (nothing catastrophic happened, ergo no one suffered!) comes to illustrate my point very well. Since we will never know the names of the people who could have got a job or raise from poverty but never had the chance to, we can gladly propose massive regulations on a global scale. In fact, it’s a very old economic fallacy, perfectly illustrated by Bastiat, Hazlitt and so many others. I can’t blame you for falling in it.
But unfortunately pure economics are out of this debate and all I’d like to learn is whether sceptic scientists’ opinions are well founded or not. To that respect, the question I posed in #171 (or rather the question I rephrased and reiterated) remains unanswered. So perhaps I should conclude that they are: the lower troposphere does not seem to warm as much as the surface, so something must be wrong with the AGW theory.
[Response: Its been the last-gasp of the skeptics for a while, but they have been obliged to abandon it. Coby has pointed you to the RC post; the wiki page has the up-to-date data and refs if you want to follow it up. Current status of the debate appears to be: AGW theory, climate models and sfc record: 1. S+C MSU record: 0 – William]
Re 189 You are correct, Mikel, to conclude that there is something wrong with the AGW theory, but you are mistaken in assuming that it means we should take no action. The Arctic sea ice and the Greenland ice sheet are melting much faster than the models predict, and it is clear to me that the models are underestimating the dangers, not overestimating them as you so blithely assume.
As far as the economic consequences of reducing the use of fossil fuels are concerned, you seem to have less evidence about that than the climate scientist have about their science. Even George W. Bush recognises that vast sums of money are flowing out of the US to pay for imported oil. If that money was retained in the US it would provide more jobs there, not less. Speculation about hypothetical unemployed workers is just scare tactics and tantamount to moral blackmail.
# 189,
I guess it is indeed fair to say that there is a problem between some of the tropospheric temperatures as measured by satellites and as predicted by models. It is quite thouroughly discussed here:
https://www.realclimate.org/index.php?p=170
But what to conclude from that? So far, errors and corrections keep getting discovered and added and the models are proving more accurate. So at the very least we must say the jury is still out. And what if the measurements continue to show this inconsistency? Then the conclusion will be the models are wrong on this aspect.
Does this shake up the climate science community? Yes. Does this impact policy decisions? I can’t see how so.
As for your point that we will never know who lost their job, I suppose that’s fair, but it is easily countered by the fact that we will likewise never know who gained a job because of new initiates. The point is that the overall numbers were not impacted.
Likewise if we finally get really serious about emissions reductions, I don’t doubt that jobs will be lost, but I do doubt that there will be no compensating growth in other economic niches to offset it. Why in the world would there not be a net gain in economic activity with so much infrastructure to modify or replace and so much new technology to develope and refine?
And as Alastair points out, finding a flaw in the theory by no means guantees that the prognosis will improve, it can just as easily indicate an underestimation in overall impacts on human lives.
> 188, predictions of economic catastrophe
One of the classics:
“OZONE AND GLOBAL WARMING: ARE THE PROBLEMS REAL? — Sallie Baliunas
“Dr. Baliunas: …. Federal regulations in 1990 were costing Americans $395 – 510 billion, or nearly $5000 per household, annually. The burden of regulations is about to ratchet up. One expensive increase will result from removing chlorine-containing refrigerants, such as Freon and other CFCs, from society. CFCs are thought to gradually erode the ozone layer of the stratosphere. The bare cost of replacing or retrofitting equipment is roughly $100 billion …. A short-term cost of $2 trillion will rip through the U.S. economy according to a 1993 estimate contained in House Resolution 291. ….”
Full document here as PDF file:
http://johnquiggin.com/wp-content/uploads/2006/01/baliunas_report.pdf
Mentioned here:
http://johnquiggin.com/index.php/archives/2003/09/14/junk-science-on-ozone/
Re: 190
The most recent study I’ve heard of says that the Greenland ice mass balance is increasing in the interior and decreasing at the edges. Total mass balance still seems “up in the air”, and not “melting faster than the models predicted”. The article below says that parts of the interior above 1500 meters are accumulating snow at something over 6 cm annually. Areas below 1500 meters elevation are losing ice at a rate of approx. 2 cm per year. The average thickness of the Greenland ice sheet is 2.3 kilometers.
To quote another part of the article:
“Modelling studies of the Greenland Ice Sheet mass balance under greenhouse global warming have shown that temperature increases up to about 3ºC lead to positive mass balance changes at high elevations “due to snow accumulation” and negative at low elevations – due to snow melt exceeding accumulation.
Such models agree with the new observational results. However after that threshold is reached, potentially within the next hundred years, losses from melting would exceed accumulation from increases in snowfall “then the meltdown of the Greenland Ice Sheet would be on.”
This statement sounds rather alarming. Rather than quibble with it, let’s assume it’s true. The time required to melt the entire sheet (or an appreciable fraction of it) would have to be measured in millenia, even assuming a massive increase in the rate of loss. If the “average” depth of the sheet is 2.3 kilometers, then if the entire sheet started losing 2 cm per year it would take 115,000 years for it to disappear. So let’s assume there’s some kind of positive feedback loop that increases the rate of loss by a factor of 10. It would still take over 11,000 years for the entire sheet to melt. This particular “danger” of global warming doesn’t seem to be particularly imminent.
Of course, the article also very correctly points out that short-term trends shouldn’t be used to make long-term predictions.
http://www.eurekalert.org/pub_releases/2005-11/esa-eas110405.php
Cheers.
Ken, the sudden acceleration of two additional glaciers was news at the December 2005 AGU, I recall. One had sped up some years ago and was thought to be an anomaly. (“Once is happenstance, twice is coincidence, three times is enemy action” comes to mind — it does suggest something new going on that wasn’t expected.)
Here’s a bit newer source:
http://www.ume.maine.edu/iceage/Research/Contrib/html/08.html
http://www.nasa.gov/vision/earth/lookingatearth/grace-20051220.html
“In an update to findings published in the journal Geophysical Research Letters, a team led by Dr. Isabella Velicogna of the University of Colorado, Boulder, found that Greenland’s ice sheet decreased by 162 (plus or minus 22) cubic kilometers a year between 2002 and 2005. This is higher than all previously published estimates, and it represents a change of about 0.4 millimeters (.016 inches) per year to global sea level rise.”
That is a correction on what seems to be happening at the moment. As for your projections into the future, you don’t know the first thing about the dynamics of ice sheets. So aside from the naive linear extrapolations based on…what exactly? history tells us a little about ice sheet collapses and my understanding is that the can happen surprisingly fast. I can’t find the quote but I do recall reading at least one researcher saying we may be looking at a few centuries or faster, not one or two millenia.
Re #189: Apparently we are supposed to imagine some fantasmagorical amount of economic growth that would have occurred if only we had never adopted the Clean Air Act, the Montreal Protocol, etc., etc.? Sounds pretty unlikely to me.
What is more likely is that entrenched special interests have a strong incentive to exaggerate the costs and minimize the benefits of such environmental regulations and they find willing accomplices in libertarian-leaning economists, politicians, and think-tanks. And, interestingly enough, even organizations like the EPA seem to consistently overestimate the costs of compliance with environmental regulations, presumably because they don’t take into account the innovative least-cost ways that the market will come up to comply. (See http://www.prospect.org/print/V8/35/goodstein-e.html .) Yes, market economic theory continues to work even in a world with certain regulations despite the libertarians’ attempts to convince us that it only works if we let the market run free with all the rampant externalities and all…Go figure!
Here’s (from a Google cache) a proposal draft for a 2007-2008 “Polar Year” study — the summary says a lot about what we don’t know yet and could find out. It’s from NASA personnel, perhaps someone can tell us more?
http://www.google.com/search?q=cache:ZpxG72006YUJ:www.ipy.org/development/eoi/details.php%3Fid%3D951+Greenland+mass+balance&hl=en&gl=us&ct=clnk&cd=51&client=firefox-a
Quoting a chunk from that [my excerpts and formatting]:
“… The airborne data, however, do not cover all outlet glaciers, and satellite radar altimetry does not cover coastal ranges where most changes take place. As a result, published estimates of the mass balance of the Greenland Ice Sheet are underestimates.”
“Moreover, recent analysis suggests that changes in velocity of the glaciers contribute for more than half of the observed mass loss, but such velocity changes cannot be measured with altimetry.”
“Another approach to mass balance is the mass budget or component method where mass outflow at the grounding line – calculated combined information on ice velocity and thickness – is compared with net accumulation upstream. …. ice thickness data are remain too sparse to measure outflow on all glaciers.”
“In the next two years, we will collect the necessary thickness data using the NASA P3 to estimate 2000 ice fluxes from Radarsat-1. During IPY, we will not re-measure ice thickness but we will re-measure ice velocity…, around the entire periphery of Greenland, except local ice caps. These new and old data will be used to estimate mass balance of all the major Greenland glaciers and changes between 1992, 1996, 2000, and 2008.”
“This is be important to determine the contribution to sea level rise of Greenland as well as identify the contribution to mass imbalance from changes in ice velocity of the glaciers. It will also identify the glaciers that are contributing the most to the imbalance of the Greenland ice sheet. Analysis of the results will be done jointly with colleagues in Denmark.”
…
“PROPOSER — Dr Eric Rignot Jet Propulsion Laboratory”
——
I hope they got funded — it was to be decided in 2005. If so, I suppose they can’t say anything before they publish. Must … be … patient.
Re #189: “To that respect, the question I posed in #171 (or rather the question I rephrased and reiterated) remains unanswered. So perhaps I should conclude that they are: the lower troposphere does not seem to warm as much as the surface, so something must be wrong with the AGW theory.”
Ah, the irony of it all! Do you realize that you are basing your entire assertion on your interpretation of the data in the figures from a draft report and yet if you go and read the executive summary of the draft report itself (available here: http://www.climatescience.gov/Library/sap/sap1-1/public-review-draft/sap1-1prd-exsum-no-figs.pdf ), it contradicts your interpretation of the data:
“During the satellite era (1979 onwards), both the low and mid troposphere have warmed. The majority of data sets show warming at the surface that is greater than in the troposphere. Some data sets, however, show the opposite â�� tropospheric warming that is greater than that at the surface.”
“For global-mean temperature changes in the new climate model simulations, some show more warming in the troposphere than at the surface, while a slightly smaller number of simulations show the opposite behavior. Given the range of observed results and the range of model results, there is no inconsistency between models and observations at the global scale.”
“[In the tropics,] the majority of observed data sets show more warming at the surface than in the troposphere, while some newer observed data sets show the opposite behavior. Almost all model simulations show more warming in the troposphere than at the surface.”
“In the tropics, the agreement between models and observations depends on the time scale considered. For month-to-month and year-to-year variations, models and observations both show amplification (i.e., the month-to-month and year-to-year variations are larger aloft than at the surface). The magnitude of this amplification is essentially the same in models and observations. On decadal and longer time scales, however, while almost all model simulations show greater warming aloft, most observations show greater warming at the surface.
These results have at least two possible explanations, which are not mutually exclusive. Either amplification effects on short and long time scales are controlled by different physical mechanisms, and models fail to capture such behavior; and/or remaining errors in some of the observed tropospheric data sets adversely affect their long-term temperature trends. The second explanation is judged more likely.”
So, now that your own source contradicts your interpretation of this being necessarily a big problem with the models (let alone with all of AGW theory), perhaps you’ll give up your claims? Or, is that source no longer looking so trustworthy to you?
Re #187
“we will never know the names or see the faces of the people who will not get a job, lose the one they have or fail to escape poverty as a result of a lower global economic growth caused by the decisions you propose”
There is no law of economics that says that avoiding using the burning of carbon will result in lower employment. What economics does say is that if additional economic resoures are used to produce energy supplies than otherwise then those economic resources will not be available for some other purpose. So yes using non-carbon-burning sources of energy will cost us some money so that’s what the argument is really about. The factor that skeptics ignore is risk. Skeptics always talk as if the risk of damage from CO2-caused global warming is zero without justifying how they come up with a figure of zero. e.g. they effectively say the risk of damage from an extra 10GT of carbon into the atmosphere every year is zero.
Re 193
If you go to http://news.bbc.co.uk/1/hi/sci/tech/4660938.stm â??Stark Warning over Climate Changeâ?? and click on the map of Greenland you get the following map;
http://news.bbc.co.uk/nol/shared/spl/hi/pop_ups/06/sci_nat_enl_1138619023/img/1.jpg
It shows that the areas which are melting are expanding into the areas where the snow is accumulating. If those melt areas continue to grow at the SAME rate, then they will have almost doubled by 2012, and nearly halved the areas where snow is accumulating. If the melting is being caused by increased greenhouse gases raising the snow line, then it is likely that their growth will accelrate rather than remain the same, since the greenhouse gas concentrations are increasing. That is without the ice albedo positive feedback effect, which will cause an acceleration even if the increase in greenhouse gas concentration is halted.
Let’s face it, the only way to stop the Greenland ice melting would be to reduce, not just our consumption of fossil fuels, but also their atmospheric concentration.
Cheers, Alastair.