In even an overview of the section in the 2007 IPCC Statement For Policymakers on “Direct Observations of Recent Climate Change” there are errors, or at best selective information, in their findings. I am summarizing four on this weblog:
1. The IPCC SPM writes on page 7
“… snow cover have declined on average in both hemispheres.”
The Rutgers University Global Snow Lab Northern Hemisphere Snow Cover Anomalies plot through January 2007, however, shows that the areal coverage in the Northern Hemisphere has actually slightly increased since the later 1980s!
Since the inference from the IPCC SPM is that global warming is the reason for these changes, this is at best a clear example of selecting a time period that conforms to their conclusion rather than presenting an up-to-date description of snow cover trends.
2. The IPCC SPM writes on page 7
“Observations since 1961 show that the average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80% of the heat added to the climate system.”
It is correct that the ocean is where most of the heat changes occur, but the finding conveniently neglected to report on the significant loss of heat in the period from 2003 to at least 2005;
Lyman, J. M., J. K. Willis, and G. C. Johnson (2006), Recent cooling of the upper ocean, Geophys. Res. Lett., 33, L18604, doi:10.1029/2006GL027033.
As stated in that paper,
“The decrease represents a substantial loss of heat over a 2-year period, amounting to about one fifth of the long-term upper-ocean heat gain between 1955 and 2003 reported by Levitus et al. [2005].”
In addition, even with the earlier ocean warming, this is what was found in the paper
Willis, J. K., D. Roemmich, and B. Cornuelle (2004), Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales, J. Geophys. Res., 109, C12036, doi:10.1029/2003JC002260.
� Maps of yearly heat content anomaly show patterns of warming commensurate with ENSO variability in the tropics, but also show that a large part of the trend in global, oceanic heat content is caused by regional warming at midlatitudes in the Southern Hemisphere. �
They report that,
“……a strong, fairly linear warming trend is visible in the Southern Hemisphere, centered on 40°S. This region accounts for a large portion of the warming in the global average.�
Also,
“……..the warming around 40°S appears to be much steadier over the course of the time series, as seen in Figure 7. In addition, this warming extends deeper and is more uniform over the water column than the signal in the tropics. �
Thus the actual global ocean warming reported in the IPCC SPM over the last several decades occured in just a relatively limited portion of the oceans and through depth such that the heat was not as readily avaiable to the atmosphere as it would be if the warming was more spatially uniform.
Moreover, if the ocean has been absorbing “more than 80% of the heat added to the climate system”, why does the SPM use the surface air temperature trends to define what is a warm year? The IPCC SPM makes such a claim on page 5, where it is written that
“Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850).”
If the ocean absorbs most of the heat (which Climate Science agrees with), than that is the climate metric that should be reported on with respect to global warming, rather than the global average surface temperature trend data.
3. The IPCC SPM writes on page 7,
“The average atmospheric water vapour content has increased since at least the 1980s over land and ocean as well as in the upper troposphere. The increase is broadly consistent with the extra water vapour that warmer air can hold.”
This conclusion conflicts with the finding in
Smith, T. M., X. Yin, and A. Gruber (2006), Variations in annual global precipitation (1979–2004), based on the Global Precipitation Climatology Project 2.5° analysis, Geophys. Res. Lett., 33, L06705, doi:10.1029/2005GL025393,
where they write for the period 1979–2004 that precipitation tends
“have spatial variations with both positive and negative values, with a global-average near zero.”
The global average precipitation has not changed significantly in the period.
If greater amounts of water vapor were present in the atmosphere, the evaporation/transpiration of water vapor into the atmosphere and thus the precipitation would have to increase when averaged globally and over a long enough time period.
4. The IPCC SPM writes,
“Mid-latitude westerly winds have strengthened in both hemispheres since the 1960s.”
This is perhaps the most astonishing claim made in the report. First, peer reviewed papers that have investigated this subject,
Pielke, R.A. Sr., T.N. Chase, T.G.F. Kittel, J. Knaff, and J. Eastman, 2001: Analysis of 200 mbar zonal wind for the period 1958-1997. J. Geophys. Res., 106, D21, 27287-27290.
did find a
“….tendency for the 200 mbar winds to become somewhat stronger at higher latitudes since 1958.â€?
However, what this means from basic meteorology, is that if the mid-latitude westerlies increase, this indicates a greater north-south tropospheric temperature gradient! This is why the westerlies are stronger in the winter; the troposphere becomes very cold at the higher latitudes, but the tropospheric temperatures change little in the tropics. Thus a statement that the westerlies have become stronger, in the absence of significant warming in the tropical latitudes, indicates a colder troposphere at higher latitude on average.
There is, therefore, an inconsistency in the IPCC SPM. It cannot both be the case that the troposphere in the arctic is warming high while the westerlies in the midlatitudes are increasing in speed. There is a fundamental inconsistency in these trends, which goes unaddressed by the IPCC.
These four examples illustrate the apparent selection of papers and data to promote a particular conclusion on climate change. The science community, and even more importantly, the policy community is ill-served by such cherry picking.
Dr. Pielke,
The issue of data presentation is one which affects many aspects of human communication… science, business, sports, etc.
With regard to projections and politics around the subjects of global warming and climate change, I have attempted to provide some perspective by demonstrating how the presentation of data may be more important than the data itself.
The first of a three-part installment appears here:
http://hallofrecord.blogspot.com/2007/02/global-warming-its-how-you-say-it.html
..
Comment by Bruce Hall — February 15, 2007 @ 10:16 am
Roger, if you are going to criticise IPCC, at least make sure your criticisms could have been addressed or are proper apples-to-apples comparisons. Papers that came out last year that weren’t in press by the time of the Second Order Draft (Mar 2006) could not have been included. That includes Lyman et al, and relevant updates at AGU last year. Though I note that that paper does not undercut the statements in the SPM at all.
Your comment about global precipitation is not contradicted by IPCC comments about water vapour. They are not the same thing. Direct observations of water vapour do show increases, and it is well understood that precipitation is not expected to scale with water vapour (i.e. Held and Soden, 2006). Nowhere in the SPM does it claim that precipitation has increased globally and in fact they go out of their way to indicate the regional nature of precipitation changes (p8).
Similarly, the 200mb winds are not what are being talked about when the SPM refers to increasing westerlies - these are references to surface winds, and specifically to shifts towards positive phases of the Northern and Southern Annular Modes in recent decades. These are not purely driven by surface temperature contrasts (Shindell et al, 2001; 2004) and so are not contradictory to ‘basic meteorology’.
Not mentioning any of these facts, could lead some to suggest you were indulging in some cherry-picking of your own!
Comment by Gavin — February 15, 2007 @ 11:37 am
Gavin- Thank you for commenting on Climate Science. I very much appreciate that you engage in constructive discussions, even on those subjects in which we disagree. We all learn from such a process.
With respect to your responses, the reported ocean cooling certainly does undercut the claim of the IPCC SPM that the “Warming of the climate system is unequivocal”. The ocean cooling started in 2003 and this data was certainly available (and should have been looked at in any balanced climate assessment, even with a cut off in early 2006).
Secondly, if evaporation increases from the ocean (as required for the positive water vapor feedback) over a long enough averaging time and globally, the precipitation must also increase. Otherwise, the mass increase of water vapor that can be “stored” in the atmosphere will quickly be a large value. With respect to directly diagnosing the water vapor in the atmosphere, as you probably agree, this is a more difficult task then diagnosing tropospheric temperature trends. The use of precipitation trends provides an alternative methodology to diagnosis atmospheric trends in absolute water vapor content.
On the issue of the westerlies, if the SPM was referring just to surface winds, which is an odd climate metric as it is so much affected by boundary layer processes, the report should have said so. Regardless, since there is not evidence of a decrease in the westerlies (indeed we found an increase), and because our paper was published prior to the IPCC cut-off date, this issue should have been included in the SPM. If the polar tropospheres are warming as a greater rate than the tropical and subtropical latitudes, we should se a decrease in the mid-latitude tropospheric westerlies.
Finally, I note that you are silent on the Northern Hemisphere snow cover trends. Does this mean we agree that this was an error in the SPM findings on this issue?
Comment by Roger Pielke Sr. — February 15, 2007 @ 12:15 pm
There seems to be a de facto ban on the use of substantial sets of post 2003 or 2004 data by the IPCC, at least there appears to have been vis a vis this 2007 report.
Comment by Steve Sadlov — February 15, 2007 @ 12:42 pm
Re #2: Gavin, Why are shifts towards positive phases of the Northern and Southern Annular Modes in recent decades relevant to climate change discussion? What are the factors driving them?
Comment by Bryan Sralla — February 15, 2007 @ 2:08 pm
I don’t know anything much about snow cover trends, and whereof one cannot speak, one must be silent… (a good maxim I find).
On oceans. The SPM is clearly talking about long term trends and since Lyman et al and Levitus all find long term warming, there is no contradiction. I don’t see how IPCC can be faulted if the processing of 2003 to 2005 data was not published in time!
On precip. You are of course correct that evaporation=precipitation on any long term average (i.e greater than a year), but the relationship between P (or E) and water vapour amount is the relationship between a flux and a reservoir. The fluxes can increase and the reservoir level not change if the residence time compensates and vice versa. In the tropics, water vapour is predicted (and observed) to go roughly like the Clasuius Clapyeron equation (i.e ~30% increase for a 3 deg C warming - if I remember correctly) while precipiation amounts are estimated to increase much more slowly (maybe 6% for the same temperature change) (Held and Soden, 2006 - a good paper, I recommend reading it!). That implies that one should expect a change in water vapour residence time with a warming climate. Given the variability and sampling issues in precipitation and an expectation of slow growth, it is not surprsing that global precipitation increases have not been detected.
Of course, increasing aerosol effects may also play a role in controlling latent heating (at least regionally), and in the AR4 models 20th C runs this implies that evaporation/precip changes are small, even as the water vapour increases in the mean (Romanou et al, in press http://pubs.giss.nasa.gov/abstracts/inpress/Romanou_etal.html ).
On the westerlies issue, I don’t follow your reasoning. The SPM correctly indicates that westerlies have increased (in accord with your analysis and ours). So I don’t really understand what you are complaining about. Your subsequent supposition that increasing westerlies can only come about from an increased surface temperature gradient is a false assumption (as the referenced papers demonstrate). There is a significant impact from planetary wave activity and it’s role in accelarating and decelarating lower stratospheric winds. Given the changes near the tropopause in the mid-latitudes (cooling in the lower stratosphere poleward, warming in the uppoer troposphere equatorward) there is an increase in upper level temperature gradients that can lead to accelarations even down to the surface (Baldwin and Dunkerton, 1999).
(on a minor point, I misspoke above when I said surface winds, I meant lower level free troposphere winds).
Comment by Gavin — February 15, 2007 @ 2:18 pm
Gavin- Thank you again for your replies.
On the issue of precipitation changes, on page 8 the 2007 IPCC SPM itself concludes
“The frequency of heavy precipitation events has increased over most land areas, consistent with warming and observed increases of atmospheric water vapour.”
While this is not a statement about global precipitation, it supports the conclusion that increases in atmospheric water vapor are assumed to be “consistent with…..increases in precipitation”. Unless the physics of rainfall processes have changed (which I agree with you is possible as a result of the diverse effects of anthropogenic aerosols on cloud microphysics; i.e. clouds have become colloidially more stable), the global average precipitation must increase when evaporation increases. The different percent increases between surface evaporation and precipitation that you describe are not sustainable, as the reservoir capacity of the atmosphere is quite small.
With respect to the statement,
“Your subsequent supposition that increasing westerlies can only come about from an increased surface temperature gradient is a false assumption”
incorrectly states our research and the basic concept in meteorology of the “thermal wind equation” (e.g. see and see).
The larger the horizontal gradient of the vertically integrated temperature in the tropopshere, the more rapidly the gradient winds increase with altitude. The winds at 300hPa in the midlatitudes averaged around the globe, for example, are greater when it is colder at higher latitudes. The observed winds in the upper troposphere, therefore, become an integrator of the tropospheric temperature gradient below that level. The value of this climate metric apparently has not been recongized adequately in the IPCC assessment.
Comment by Roger Pielke Sr. — February 15, 2007 @ 3:01 pm
Roger, the statements about precipitation intensity are not the same as global precipitaiton amounts. There is good evidence that these have increased, and that this is consistent with climate model projections (Meehl et al, 2006). It would be better all around if we just discussed what the SPM actually says rather than extrapolating to something different.
It may come as a surprise, but I am aware of the thermal wind equation. To answer Brian’s question, there are at least three potential reasons why increasing mid-latitude westerlies might be expected. These factors have been suggested by Hoerling et al (2000), Shindell et al 1999 and Shindell et al 2004, and are - increased tropical ocean warming, increased GHGs leading to a cooler stratosphere and warmer troposphere and increases in ozone depletion (in the southern hemisphere). Each of these effects acts to increase the upper-tropospheric equator to pole temperature gradient in temperature near the mid-latitude winter jets and has been shown in models to qualitatively match the obs (Miller et al, 2006).
Comment by Gavin — February 15, 2007 @ 5:22 pm
Re: #6 and #7: I will rephrase my last question and ask both of you distinguished experts.
Why are shifts towards positive phases of the Northern and Southern Annular Modes in recent decades relevant to (GHG-forced) climate change discussion? Are we certain this is what the SPM was referring to?
Comment by Bryan Sralla — February 15, 2007 @ 5:45 pm
Gavin - I have a way to resolve our disagreement. Show me a paper (or perform new analysis) that diagnoses the zonally averaged 700 hPa, 500 hPa and 200 hPa east-west wind trends for the last several decades in the latitude bands of 30-40, 40-50 and 50-60. These can be coverted to a zonally averaged tropospheric temperature gradient below these levels.
If the conclusion that you reach from the papers you cite is correct, than only at the 200 hPa level or above would there be an increase in westerlies. At lower levels there would not be such an increase, and indeed if the lower and middle troposhpere in the higher latitudes are warming, the westerlies at those levels should be decreasing.
This is a diagnostic that should be included as part of the observational analysis and model simulation test in any climate assessment. Moreover, since the mid-latitude circulation features in the lower and middle troposphere are so important for the weather than occurs, changes in the winds at these levels should have been a high priority in the IPCC assessment (and perhaps it is in the chapters).
With respect to the 2007 IPCC SPM, the statement
“Mid-latitude westerly winds have strenthened in both hemispheres since the 1960s”,
does not make the clarifications that you have written above. Indeed, as our discussion shows, it is actually very misleading in its implications if the intention was to report on only the upper level troposphere.
Comment by Roger Pielke Sr. — February 15, 2007 @ 6:12 pm
RE #6 etc -
I find it interesting that the 2007 IPCC SPM (and apparently then the future release later this year of the science, by the scientists, which must be edited to match the production by the political representatives) does not include information after 2003, at the cessation of the current warming trend.
However, how is this actual data which was in fact released 4 years ago, in 2003:
http://www.nasa.gov/centers/goddard/news/topstory/2003/0530earthgreen.html
included in the modeling of precipitation trend forcings?
Or was it?
Comment by Steve Hemphill — February 15, 2007 @ 9:55 pm
Gavin : “Given the changes near the tropopause in the mid-latitudes (cooling in the lower stratosphere poleward, warming in the uppoer troposphere equatorward)”
Gavin, I don’t clearly understand this point. When I look at RRS MSU data for 1979-2006 (or 1987-2006 for TTS), I see for the Northern Hemisphere :
- more warming in upper tropo (channel TTS) in pole than in tropics
- more warming in lower strato (channel TLS) in pole than in tropics
So, I would say warming trends are convergent poleward at each level of the atmosphere (for NH). May be I miss the correct geopotential (but anyway, channel TMT is coherent, with here also more warming poleward). Or maybe you’ve Southern Hemisphere in head?
MSU (synthese maps, near the end of the page) :
http://www.remss.com/msu/msu_data_description.html
Comment by Charles Muller — February 16, 2007 @ 3:06 am
After the wet 2005 autumn, Northern Italy is under the effects of a 5 season long drought. Data since 1951 show that 2006 was the driest year in the region where I live (the southern part of the river Po valley), but the second half of the ’80s was the driest period. Not yet aggregated data seem to show that the ’40s were the driest decade and 1945 the driest year.
What is worth to mention is that there is not a trend in precipitation but rather an abrupt shift in the early ‘80 when winter precipitation decreased by 24% (-13% in spring).
If one looks at the blocking activity in the North Atlantic region, there was a remarkable decrese in the number of blocking in the early ’80s.
I ask you if is there a trend in the westerlies or just a change in the ’80s?
Back to the precipitations in my region: the number of the heaviest events (area averaged rainfall > 40 mm/day) is invariably fixed to 3-4 in a 5 year period and also the number of lighter events has not changed; the middle intesity class had a slight decrease.
Comment by Paolo M. — February 16, 2007 @ 3:38 am
Something else that I find confusing in the SPM is the statement regarding methane.
The SPM says “Growth rates have declined since the early 1990’s, consistent with total emmissions (sum of anthropogenic and natural sources)being nearly constant during the period. It then goes on to say “but the relative contributions from different source types are not well documented”.
Now if the relative contributions from each source type (natural vs agriculture and fossil fuel use) are not well documented, then how can we possibly have confidence as to why the methane levels have stopped increasing? I am sure that there is a changing isotope signiture to the d13C1 of CH4, but when the methane is a mixture of sources, the isotope ratios may not be diagnostic of the relative contributions of the sources.
I suspect the IPCC is too smug about what it thinks it knows about methane and system feedbacks regulating its concentrations. In light of the continued increase in population and hydrocarbon combustion, the leveling off of methane came as a surprise.
Comment by Bryan Sralla — February 16, 2007 @ 9:53 am
The use of the term ‘westerlies’ in the SPM is at best, ambiguous. I had the same take as Roger, believing the summary was referring to mid and upper level winds and wondering how that supported their argument. If they are speaking specifically about low-level westerlies, it is very sloppy that they weren’t more specific.
As to water vapor:
There is this:
“The global time series of NVAP (NASA Water Vapor Project) TPW (total percipitable water) anomalies does not show a consistent trend from 1988 – 1999. The first half of the period is marked by a downward trend, while the second half is marked by an increase. The overall trend during this period (1988-1999) is –0.29 mm / decade.
-WATER VAPOR TRENDS AND VARIABILITY FROM THE GLOBAL NVAP DATASET - 2001
Thomas. H. Vonder Haar, John M. Forsythe, Johnny Luo, David L. Randel and Shannon Woo
There is a similar study done by Trenberth et al that does find a positive trend. (I am not good with links, but if you copy the title of the above paper into google you will get links to both right away.)
The interesting thing about both papers is that any results that seem to be in agreement with the hypothesis are assumed to be robust, and any findings contrary to the support of a strong positive water vapor feedback are deemed questionable, with possible reasons why the data may be wrong. Trenberth et al go on to assume that the data set is just not long enough for areas that don’t show the expected trend, but data sets of the same length for regions that do show the trend are quite sufficient to demonstrate the robustness of the theory! It seems that Cherrypicking is reaching the level of an art form!
Good science demands that all data should be subjected to suspicion, not just the data that is inconvenient.
The IPCC and much of the climate change community seem to believe that they can ignore a large amount of inconvenient data by simply questioning its robustness. At the same time, they totally embrace weak and ill founded science, like the hockey stick and the sulfate aerosol cooling of the mid-20th century, without the least bit of concern for the blatant discrepancies!
In the short term, this anti-science behavior has been very good for the Climate Change Community ($$$). In the long run, it will cause much more harm than good, resulting in the loss of respect for the atmospheric sciences and, more importantly, in the implementation of counterproductive, costly policies.
Comment by Jim Clarke — February 16, 2007 @ 9:58 am
RE: #13 - Fascinating. An interesting side note is that what has been happening this winter in much of Europe, is portrayed in the main stream media as simply a warm spell. But I think what is really going on is an oscillation in temperature, during a drought. The drought bears more responsibility for the lack of snow cover than the warmth.
Comment by Steve Sadlov — February 16, 2007 @ 12:11 pm
Roger,
Visually examining the snow cover anomaly data you link, I am inclined to conclude that there is no secular trend apparent in the plot but rather a mode shift from a positive anomaly state to a negative anomaly state. This strikes me as more consistent with cyclic change in state rather than a trend. It is shoddy work to take a data set and perform a linear least squares fit and assume the the trend (the “fit” that is) has some real world physical significance. This sort of things seems to have also been done with the unprecedented Alaska warming “trend” that was more of a shift in temperature in the mid 70’s.
And a quibble with the SPM authors in your item 3, quote:
“The average atmospheric water vapour content has increased since at least the 1980s over land and ocean as well as in the upper troposphere. The increase is broadly consistent with the extra water vapour that warmer air can hold.�
So long as the atmosphere is not in a saturated state it is the temperature of the liquid water that determines the vapor pressure above the liquid water not the temperature of the vapor space. Of course the liquid and vapor can exchange heat, sensible and latent, but it is still the liquid temperature that drives evaporation. This may seem minor but I think it shows a certain intellectual laziness about process.
Tom Gannett
There, I’ve out-ed myself in the interest of full disclosure.
Comment by Shoes — February 16, 2007 @ 3:45 pm
#15
Jim, in addition to your comment::
16th Conference on Climate Variability and Change (2005) : no global trend for WV for 1988-2001
Water Vapor Trends and Variability from the Global NVAP Dataset
Thomas H. Vonder Haar, J. M. Forsythe, J. Luo, D. L. Randel, and S. Woo
The NASA Water Vapor Project (NVAP) dataset is a global, daily, multilayer and total column, satellite-derived water vapor dataset that currently covers the time period from 1988 – 2001. This paper will discuss significant interannual variability and noteworthy variations on shorter timescales. Maps of the daily change in layered and precipitable water vapor, both in absolute and relative terms, are presented. They highlight regions where atmospheric moisture is most variable, such as midlatitude storm tracks and adjacent to the ITCZ. Examination of the water vapor record on longer timescales indicates different atmospheric processes such as the monsoons and ENSO. The NVAP dataset does not show a convincing global trend of water vapor. There are however significant regional trends during this time period. Extension of the NVAP dataset beyond 2001 and synergy with other global climate datasets (clouds, precipitation, global temperature) will be discussed.
http://ams.confex.com/ams/Annual2005/techprogram/paper_84927.htm
The Trenberth 2005 paper can be download here :
http:// http://www.cgd.ucar.edu/cas/Staff/Fasullo/refs/Trenberth2005FasulloSmith.pdf
Their conclusion : a positive global trend for 1988-2003, with regional increase and decrease, but mostly with a dominant ENSO signal :
“It is evident that the analysis of precipitable water variability is dominated by the evolution of ENSO and especially the structures that occurred during and following the 1997–1998 El Nino event.”
Another interesting point in Trenberth 2005 : a negative trend over Europe… whereas surface warming of the past 20 years has been particularly pronounced here.
Comment by Charles Muller — February 16, 2007 @ 6:17 pm
Re 17. “So long as the atmosphere is not in a saturated state”
Please see
Ruckstuhl, Christian, Rolf Philipona, June Morland, and Atsumu Ohmura, 2007. Observed relationship between surface specific humidity, integrated water vapor, and longwave downward radiation at different altitudes. J. Geophys. Res. - Atm., 112, D03302, doi:10.1029/2006JD007850, February 2, 2007
Abstract
Atmospheric water vapor and surface humidity strongly influence the radiation budget at the Earth’s surface. Water vapor not only absorbs solar radiation in the atmosphere, but as the most important greenhouse gas it also largely absorbs terrestrial longwave radiation and emits part of it back to the surface. Using surface observations, like longwave downward radiation (LDR), surface specific humidity (q) and GPS derived integrated water vapor (IWV), we investigated the relation between q and IWV and show how water vapor influences LDR. Radiation data from the Alpine Surface Radiation Budget (ASRB) network, surface humidity from MeteoSwiss and GPS IWV from the STARTWAVE database are used in this analysis. Measurements were taken at four different sites in Switzerland at elevations between 388 and 3584 m above sea level and for the period 2001 to 2005. On monthly means the analysis shows a strong linear relation between IWV and q for all-sky as well as for cloud-free situations. The slope of the IWV-q linear regression line decreases with increasing altitude of the station. This is explained by the faster decrease of IWV than of q with height. Both q and IWV are strongly related with LDR measured at the Earth’s surface. LDR can be parameterized with a power function, depending only on humidity. The estimation of LDR with IWV has an uncertainty of less than 5% on monthly means. At lower altitudes with higher humidity, the sensitivity of LDR to changes in q and IWV is smaller because of saturation of longwave absorption in the atmospheric window.
Comment by Timo Hämeranta — February 17, 2007 @ 3:08 am
[...] Update: A serious discussion on Climate Change. The more discussion the better. We may not be scientists but we must be wary of the unintended consequences of not testing the environmentalist community. They are often activists with agenda [often to raise funds for something completely opposite.] [...]
Pingback by Joseph Butson — February 17, 2007 @ 8:18 pm
There is another error (or, at least, seriously misleading statement) in the SPM:
“Since IPCC’s first report in 1990, assessed projections have suggested global averaged temperature increases between about 0.15 and 0.3 C per decade for 1990 to 2005. This can now be compared with observed values of about 0.2 C per decade, strengthening confidence in near-term projections” (p. 13).
There is no basis for attaching greater confidence to near-term projections as a result of a coincidence between the increases in observed and projected global mean temperature. The relevant comparison is between the observed increase in temperature and the increase that WOULD HAVE BEEN PROJECTED if the best estimates that are now available of emissions and forcings had been available when the near-term emissions were prepared.
In “The Consistency of IPCC’s SRES Scenarios to Recent Literature and Recent Projections” (”Climatic Change”, 2006, 75: 9-46) van Vuuren and O’Neill noted that:
“Aerosols from sulfur emissions can have a significant cooling effect and therefore form an important element of the SRES scenarios… In SRES, worldwide sulfur emissions were assumed to decline by 3% in the 1990-2000 period… Studies that estimate actual trends in that period now find that worldwide emissions actually decreased by a much larger amount (around 20%)… Compared to all other variables then, the degree of inconsistency of SRES with … historical emission trends … is highest for sulfur emissions. Corrections of the SRES emissions projections downwards … would have an upward effect on the near-term temperature ranges associated with the SRES scenarios… [A] revision of scenarios is likely to result in lower sulfur emissions. Other factors being equal, such a revision would imply an increase in the expected short-term temperature change associated with the SRES scenarios” (pps. 38, 39, 40 and 42).
Having decided that “The SRES scenarios provide a credible and sound set of projections, appropriate for use in AR4″, the IPCC appears to have failed to note that, in its own terms, the rough equivalence between observed and projected temperatures between 1990 and 2005 could well DIMINISH confidence in the capacity of the models to project temperatures. We outsiders can’t be sure of this until the IPCC reveals the basis on which it has made its claim, when the Report is published in May.
It would appear to be a quite simple matter to rerun the SRES projections as in the tables in Appendix II to the WGI Contribution to the TAR, but using the best estimates now available of the forcings. I wonder why this exercise has not been carried out.
As all seven models illustrated in Figure 9.15 of the TAR showed the A1T as having the highest temperature increase and the lowest sulfur emissions of any of the scenarios to 2030, and as the estimates of sulfur emissions are estimated to have already been as low in 2000 as were projected for 2030 in the A1T scenario, one would expect that revised projections would be for substantially higher increases in temperatures than have been observed. Perhaps this can be taken up in the Contribution of Working Group III, which has yet to be finalised.
Comment by Ian Castles — February 17, 2007 @ 11:00 pm
Re #21:
Unfortunately I am too bussy to read the SPM carefuly, but reading Ian’s comment I cannot help but catch on to the very odd way one is trying to get a positive “grade” for obviously inconsistent near-term projections.
Indeed, comparing the projections done at the time of the first report and since, with observations is in error because the used forcing agent trends are off.
It’s like saying “We projected you to get ill by ingesting too many apples, and since then we observed you getting ill, which strengthens our confidence in projecting your illness.”, while in reality you got ill by eating bad Oranges.
In more formalized words: Reaching a conclusion consistent with observations using invalid premises or model is not support for the model or reasoning.
One can also say: “reaching the right conclusion for the wrong reasons can never be support for the argumentation.”
Comment by Florens de Wit — February 19, 2007 @ 2:42 am
To Mr. Pielke Sr.,
Regarding point 1, I am curious as to why the words “Mountain glaciers and …” were omited from your quote of pg 7 of the IPCC summary, to read “Mountain glaciers and snow cover have declined on average in both hemispheres.” The time period they seem to refer to is shown on pg 6; which starts in the 20s, not the ‘later 80’s’.
Additionally, the Rutger’s graph you do link to seems optimized to show ‘anomolies’ of snow cover in the Northern Hemisphere (which you do distinguish), not the more general global snow cover patterns; and this seems to have less to do with mountain glaciers; additionally their graph starts in the mid 60’s, not the 80’s (nor the 20’s).
1988 is a bad year for snow cover, but starting there is just begging to have someone call you a cherrypicker. At best snow cover patterns might be better reffered to as ‘in recovery’. (?)
All in all you seem to be comparing half an apple to a pear, while ignoring the orange (glaciers).
-sam
( I’m nobody. A nobody at all. But the secrets of the universe don’t mind. They reveal themselves to nobodies that care. OUTER LIMITS: Galaxy Being)
Comment by Sam-Hec — February 21, 2007 @ 5:01 am
Sam-Hec Thank you for your comment.
The “Mountain glaciers and” was not included as the two climate metrics are separate. With respect to the time period that they start with in the 1920s, there hardly is the same data coverage than as there has been over the last couple of decades. Their figure is another example of mixing “apples and oranges” as the data quality and coverage varied so much over this time period. The use of the Northern Hemisphere snow cover data is appropriate as there is comparatively little land cover in the Southern Hemisphere. In any case, they specifcally stated that the decline was in “both hemispheres”.
Finally, please see our papers on the snow cover trends,
Pielke Sr., R.A., G.E. Liston, and A. Robock, 2000: Insolation-weighted assessment of Northern Hemisphere snow-cover and sea-ice variability. J. Geophys. Res. Lett., 27, 3061-3064.
Pielke Sr., R.A., G.E. Liston, W.L. Chapman, and D.A. Robinson, 2004: Actual and insolation-weighted Northern Hemisphere snow cover and sea ice — 1974-2002. Climate Dynamics, 22, 591-595 DOI10.1007/s00382-004-0401-5.
With respect to snow cover
Comment by Roger Pielke Sr. — February 21, 2007 @ 8:11 am
Roger - Howdy!
There are lots of fruits in this thread (apples, oranges, and cherries). You have emphasized four of the errors in the IPCC AR4 SPM. How much of it do you agree with? I’m personally around the 95% level … on the whole, I think it’s a pretty good summary and a reasonable starting point for discussion or policy consideration.
On another matter, the AMS Climate Change Informational Statement has been approved and is now posted. You blogged on the draft statement; any plans for an update?
I submitted fifteen criticisms and the final statement successfully repairs thirteen of them. So my agreement level with the AMS statement is around 98%, making it a very good statement in my opinion. I noticed that many of the points you blogged about were not significantly altered in the final statement, so the amount you agree with will probably be less.
Comment by John Nielsen-Gammon — February 21, 2007 @ 11:55 am
Hi John- Thank you for participating on Climate Science!
With respect to your questions, I did comment recently on the AMS Statement and it is posted here
http://www.climatesci.org/2007/02/05/the-february-2-2007-american-meterological-society-statement-on-climate-change/.
Clearly, you and I disagree on the IPCC Statement. My perspective is accurately represented by the Executive Summary findings in
National Research Council, 2005: Radiative forcing of climate change: Expanding the concept and addressing uncertainties. Committee on Radiative Forcing Effects on Climate Change, Climate Research Committee, Board on Atmospheric Sciences and Climate, Division on Earth and Life Studies, The National Academies Press, Washington, D.C., 208 pp.
The AMS Statement failed to communicate these issues to our professional community. In addition, the Committee that completed the Statement has a clear conflict of interest (i.e. even involved with law suits on this subject). Even if you agree with the Statement, the completion of such a politically charged statement by just a few individuals (no matter how qualified in their specific research area) should be troubling to all us.
Comment by Roger Pielke Sr. — February 21, 2007 @ 12:15 pm
Florens de Wit, Thank you for your comments on my posting #21, especially for your pertinent “apples v. bad oranges� illustration.
In the SPM of the 2001 Assessment, the IPCC said that the higher projected temperature increases than in its 1995 assessment “are due PRIMARILY to the lower projected sulphur dioxide emissions in the SRES scenarios relative to the IS92 scenarios� (EMPHASIS added): that is, the Panel put forward the reduction in projected sulphur emissions as the MAIN reason for the increase in the upper end of its warming range to 2100 from 3.5 to 5.8C.
Projected SO2 emissions in 2000 in the IS92a emissions scenario used in the 1995 assessment were 79 TgS (IPCC, Climate Change 2001: The Scientific Basis, Appendix II, Table II.1.8); the corresponding projections in the SRES, which was published in 2000, were 69 TgS for all scenarios (also shown in Table II.1.8); and actual SO2 emissions in 2000, as estimated in the studies cited by Van Vuuren and O’Neill, 2006, Climatic Change, vol. 75, p. 38 were: Smith et al (2004a), 57.5 TgS; Amann (2002), 57 TgS; and Stern (2003), 51.9 TgS.
Thus the SAR projected SO2 emissions in 2000 to be 40-50% higher, and the TAR projected these emissions to be at least 20% higher. than they are now estimated to have been. These projections of sulphur emissions were used to project the sulphur aerosol burden (see the Note to SRES Table II.2.7) and thence to the projections of forcings and, ultimately, of temperatures. It raises a serious question about the models that the latter projections turned out to be close to the mark, notwithstanding the large difference between projections and outcome in the input assumptions relating to sulphur.
It is surprising that neither the scientists in IPCC Working Group I (WGI), nor the “Representatives from 113 governments [who] reviewed and revised the Summary line-by-line�, realised the need to adjust the input projections before comparing the output projections with observations and concluding that their rough correspondence STRENGTHENS confidence in near-term projections.
It is worth recalling in this connection that on 30 October 2002, before the IPCC had begun preparations for its Fourth Assessment Report, Dr. John Mitchell, Chair of the JSC/CLIVAR Working Group on Coupled Models, wrote to Dr. Pachauri, Chairman of the IPCC. on behalf of the Group to argue that:
“… [T]here is little scientific justification in running new scenarios since the resulting climate change outcome is unlikely to be indistinguishable (sic) from existing scenarios with similar radiative forcing… [W]e believe that [it] is better not to try and run new model experiments, but to stick to the scenarios used in the TAR. This will allow a better definition of the range of uncertainty in projected changes due to model uncertainty and natural variability, which are likely to dwarf any differences due to TWEAKING the existing emissions scenariosâ€? (EMPHASIS added).
The “tweaking� phrase was used repeatedly by WGI scientists at the IPCC Expert Meeting on Emissions Scenarios in Amsterdam in January 2003, as an argument against revising or extending the emissions scenarios used in the TAR for the IPCC’s Fourth Assessment Report. The IPCC did not producee a report on that Expert Meeting, in which the Co-chairs of IPCC WGI (Dr. Susan Solomon), WGII (Professor Martin Parry) and WGIII (Dr. Bert Metz) all participated, and subsequently decided that the emissions scenarios prepared in the late 1990s were suitable for use in the Fourth Assessment Report. The statement about the strengthening of confidence in the models (SPM, p. 13, first bullet point) shows that the IPCC has still not understood the implications of its decision to persist with the SRES scenarios notwithstanding the fact that the projections for 2000 were seriously astray in important respects.
Comment by Ian Castles — February 24, 2007 @ 1:40 am
As a newcomer to this site I am curious about your views on fellow MIT climatologists Lindzen and Emmanuel. Have been participating in the realclimate blog for a while and find the differences between the believers and the deniers quite amazing. Those who believe the AGW hypothesis has been proven are quite outspoken in their cant against the non-believers. I thought this was about science…
Comment by john graves — February 25, 2007 @ 2:52 pm
John - Thank you for looking at Climate Science!
Both Dick Lindzen and Kerry Emmanuel are internationally well respected scientists. Their conclusions on climate science are valuable contributions to the debate.
Comment by Roger Pielke Sr. — February 25, 2007 @ 6:39 pm
further clarification of my views at reasic/wordpress.com/2003-02-23/what-would-make-me-change-my-mind (I think, my computer skills are lacking…
Comment by john graves — February 25, 2007 @ 7:48 pm
Congratulations, Johh, on your “graduation”. You will find much less chaff (aka dogma) here than at realclimate, desmogblog, et al.
One big example - the fact that temperature changes lead CO2 changes in the paleorecord means that CO2 changes cannot have caused temperature changes in the past is understood here and ignored there for the most part (or the “reasoning” is that the original causes magically went away and suddenly CO2 took over…).
Comment by Tim Clear — February 25, 2007 @ 9:53 pm
Correlation does not necessarily imply causation. Thank you for your comments! Actually, I have been led to RC through junckscience and Dr. Matthews. I have been curious about GW for many years. My general suspicions about consensus are a result of an optimistic skepticism. Conspiracy theories have always intrigued me, as well. The complex, chaotic nature of the physical and human world mitigate against such global hypotheses. Renaissance man aside, none of us are smart enough to stay outside the mean (or median) for long without being noticed.
I have read the pre-release of the SR4 and took away, non-scientifically, a sense of a toning down of the retoric. My concern is that the science is giving way to policy (and consequent politics), as RC et al quibble over who said what and why their are apostate. The Brits lead the charge into ‘personal carbon allowances’, while a third of the global population strives to emulate the Western world. I heartily encourage and endorse their emergence from dung/wood burning technology. The millions of minds set free by proper caloric intake, pre/post natal care and simple human rights will compel all of us to continue our striving for excellence. Hope is preferred to fear, Simon wins over Erlichs/Stern - I hope!
Comment by john graves — February 26, 2007 @ 8:52 am
RE: #32 - I heartily encourage and endorse their emergence from dung/wood burning technology.
A trade off analysis between subsistence lifestyles and “developed” ones in the classical Western mold is fascinating. What you find is, higher life expectancy, lower cancer rates, and eventually slightly negative population growth. Sounds pretty good to me!
Comment by Steve Sadlov — February 26, 2007 @ 1:36 pm
Roger, thanks for your response (#26); sorry I missed the blog on the AMS statement the first time. It is possible (I am an example) to mostly agree with both the NRC report and the IPCC summary. I haven’t sat down and compared them word by word. They are not in direct conflict in the sense that the IPCC summary’s purpose is to summarize past science while the NRC report’s purpose is to guide future science.
With respect to the AMS process, ten seems like about the right number to draft a statement of this length effectively. Even if one person had drafted it, so what… the quality might have suffered, but the key step would still be the approval by the AMS council, our elected representatives. I would have been troubled if the statement had taken a political position, but it does not. The “politically charged” nature of the topic ensures that the statement will undergo careful scrutiny from all sides invested in the political process, so I have no doubt that any important errors in the statement that survived the public comment stage will be brought to light in this blog or elsewhere.
Comment by John Nielsen-Gammon — February 26, 2007 @ 6:11 pm
#33.
Yes, Steve. Wealth allows for each of those and many more, including an increasing awareness of species impact, concern about it and resultant action. If the doomsayers want results quick, encourage transferable property rights,equal human rights to women, minorities, etc., reasonable health care access, human productivity rights to parents and the right to succeed or fail in business, with minimal external interference. Fear is not an efficient stimulant, desire is more so.
Comment by john graves — February 26, 2007 @ 9:08 pm
Does the temperature of the earth’s core enter into the GW debate? It would seem to have a more immediate effect on changes in the temperature/heat content of the oceans, and would expain why the Oceans are warming faster? than the atmosphere.
Comment by Keith Rogstad — February 27, 2007 @ 7:12 pm
Keith- A very good question!
The assessments of the heat supplied from the Earth’s core is a quite small component to the Earth’s climate system, as the crust and the deep ocean quite effectively insulates the upper ocean, land surface and the atmosphere from a significant heating.
Comment by Roger Pielke Sr. — February 27, 2007 @ 9:15 pm
John-
The IPCC and NRC reports are significantly different. Where in the IPCC, for example, did they address the NRC statement that
“Despite all these advantages, the traditional global mean TOA radiative forcing concept has some important limitations, which have come increasingly to light over the past decade. The concept is inadequate for some forcing agents, such as absorbing aerosols and land-use changes, that may have regional climate impacts much greater than would be predicted from TOA radiative forcing. Also, it diagnoses only one measure of climate change—global mean surface temperature response—while offering little information on regional climate change or precipitation. These limitations can be addressed by expanding the radiative forcing concept and through the introduction of additional forcing metrics. In particular, the concept needs to be extended to account for (1) the vertical structure of radiative forcing, (2) regional variability in radiative forcing, and (3) nonradiative forcing…”
[http://books.nap.edu/openbook.php?record_id=11175&page=4]
I recommend that you do compare the NRC findings with the IPCC SPM. You will find that there quite different in very important ways, as has been documented on Climate Science.
On professional statements by scientific societies, if they insist on this, they should be voted on by all of the members. I would vote to reject the current AMS Statement since it is seriously biased in its presentation.
Comment by Roger Pielke Sr. — February 27, 2007 @ 9:30 pm
John Graves makes a very important point.
I have read a lot of commentary wrt to AGW, its putative contributors,and the economic and ecological externalities which might arise from policy shifts.
Speaking as a medical practitioner working with the poorer sectors of New Zealand society I can assure all privileged Western academics et al that these poor folk have zero concern re GW. I suspect that this lack of concern extends to 50 or more % of the human population.
Unless these folk are some how rapidly enriched and educated, there is no reason why they should care about the planet at all.
Comment by andrew montgomery — March 1, 2007 @ 4:12 am
Dear Dr Pielke
I have a question to which I have not received an answer that I can understand.
I am agnostic wrt to the human contribution to global warming.
I have read widely wrt the issue over the last 4 months and still do not undestand how it is that CO2 could exert a logarithmic feedback.
I need to understand climate science as thoroughly as is possible as I intend to enter the political arena.
I am not a “denialist” or “sceptic”.
I simply want to understand the processes.
I have degrees in medicine, biochemistry and cell biology.
I have read through the “blogs” by Tim Lmbert and Mr Rabett.
I have read the many references to which I have been directed.
I have concluded that there is a consensus re AGW, but not as to its extent.
I welcome any clarification
Regards
Andrew Montgomery
Comment by andrew montgomery — March 2, 2007 @ 5:42 am
Andrew - thank you for your interest in Climate Science.
With respect to the logarithmic relation between the atmospheric concentration of CO2 and its absorption of long wave radiation, this occurs because more and more of the wavelengths become saturated as the concentrations increase. Observations of CO2 absorption in the atmosphere and in laboratories confirm this behavior and the models adopt parameterizations based on this relationship.
For more details, I recommend the book;
Remote Sensing of the Lower Atmosphere: An Introduction by Graeme L. Stephens (Hardcover - April 1, 1994)
[although since it is an expensive book, checking from a library would be recommended at least until you look at it].
Comment by Roger Pielke Sr. — March 2, 2007 @ 7:18 am
Thankyou Roger
Comment by andrew montgomery — March 2, 2007 @ 9:20 pm
Dr Pielke
I have looked at the related papers and the discussion concerning water vapor .
It appears to me that you have clearly an important point there and am disappointed that the IPCC crowd couldn’t (wouldn’t ?) try to find an argument supporting their views .
Clearly if global evaporation increases then global precipitation increases all averaged over several months to 1 year .
There is only 1 way I see that could change it over a longer period (no idea how long but perhaps longer than 1 year) and that is by increasing the average time of residence of water vapor in atmosphere .
In that case we would have a transitory where the water vapor content of the atmosphere would increase with increasing evaporation yet not generate an increase of precipitations immediately .
I see at least 2 reasons why that would not hold water (no pun intended) :
- first a notion of a transitory would imply that we had an equilibrium before . But there had never been an equilibrium so this kind of transitory has been taking place since a billion of years and the system would be producing E=P all the time regardless of the absolute amount of water in atmosphere .
- second while I can see why in theory a water molecule would decide to condensate later if it has a higher energy (thus increasing time of residence) , I am not sure that that is what happens in the clouds where the slight increase in energy coming from the temperature increase would be negligible wrt the condensation process on nuclei . The poor understanding of this process nonwithstandig .
Therefore it should follow that if dP = 0 then dE = 0 (in average) .
However what is not clear to me is if IPCC says that dE0 (in average) what would be probably false considering that observation tells us that dP = 0 or if it says that the water content of the atmosphere changes what might be true or false and depend on millions of other parameters .
Did you obtain a clarification of that statement ?
Comment by Tom Vonk — March 15, 2007 @ 9:12 am
A correction to the § before last , it should read :
“However what is not clear to me is if IPCC says that dE is different from 0 (in average) what would be probably false considering that observation tells us that dP = 0 or if it says that the water content of the atmosphere changes what might be true or false and depend on millions of other parameters .”
Comment by Tom Vonk — March 15, 2007 @ 9:16 am
Tom - Thank you for your comments.
Unfortunately, there has been no further response on the issue. Clearly, regardless of residence time of water in the atmosphere, if the input (evaporation increases), the atmosphere will not continue to accumulate this additional water indefinitely, but precipitation must necessarily increase. When the accumulation of any of the added water ends, evaporation will equal precipitation. This is straightforward mass conservation which I do not know how to explain any clearer to Issac Held and Gavin Schmidt.
Comment by Roger Pielke Sr. — March 15, 2007 @ 9:42 am
Thanks for your answer Roger .
What I thought , but I might be wrong , is that they agree with the idea that E=P (that’s mass conservation after all) but NOT with the timing .
They seem to say “As the atmosphere can accomodate more water vapor than it has right now , when the temperature increases , the additional water vapor begins to get stored in the atmosphere first and transforms in additionnal precipitation only when some (unknown) saturation ceiling is hit .”
If that interpretation is right , then they obviously think that this saturation ceiling has not yet been hit .
That would be the idea of a transient evolution .
For instance if I have a system in equilibrium and apply brutally a temperature echelon , that’s what might well happen for a certain time .
But that idea seems so absurd that they must mean something else and I can’t still understand what it might be .
The least what one could say is that they are not very helpful in providing reasons why they write some very strange things .
Comment by Tom Vonk — March 15, 2007 @ 11:46 am
Re: #31 and @all
As a novice I have some questions about that.
What exactly triggers the effect of temperature fall from the temp/CO2 diagram?
I’m no scientist, but I took my time to study this all for some weeks now and begin to form my own opinion about climate change.
CO2 rising is indeed existent, no doubt.
But is this really the main trigger for global warming?
I read about influence of the suns magnetic field on earth and that sounds proper and plausibly to me.
Although some moan about that and deny this theorie, I found an essay some days ago, that says not even earth is going through global warming, but many other planets and moons in our solar system do so too.
What about the CO2 theorie now?
If solar influence and cosmic rays as supposed generators for cloud condensation nuclei and therefore responsible for clouds, this whole CO2 discussion might be redundantly.
Or not?
And another question:
Is the now existing more than doubled solar magnetic field responsible for continental drifting and therefore Tsunami?
Can you help me with this?
(Sorry for my bad school english)
Comment by Peter MĂĽller — March 28, 2007 @ 3:43 pm