Fifty Years of Pan Evaporation and Solar Radiation Data: What Do They Tell Us About Climate Change?

Center for the Study of Carbon Dioxide and Global Change ^ | 01/07/03 | Number_cruncher

[Number_Cruncher]

Fifty Years of Pan Evaporation and Solar Radiation Data: What Do They Tell Us About Climate Change?

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Reference
Roderick, M.L. and Farquhar, G.D.  2002.  The cause of decreased pan evaporation over the past 50 years.  Science 298: 1410-1411.

Background
"As the average global temperature increases," say the authors, "it is generally expected that the air will become drier and that evaporation from terrestrial water bodies will increase."  However, as they continue, "terrestrial observations over the past 50 years [when they assume the planet warmed by ~0.15°C] show the reverse."  Hence, they set out to explain this seeming "paradox."

What was done
Based on measurements of total solar irradiance (RS) from the northwest part of the former Soviet Union (49-67°N) for the period 1960-1990, which revealed RS to have decreased by 2 to 4% per decade, the authors used an energy balance approach to calculate the expected change in annual pan evaporation, comparing their result with the observed change in this parameter over the same region and time period.

What was learned
The authors ended up demonstrating that the observed decrease in pan evaporation is both qualitatively and quantitatively consistent with "what one would expect from the observed large and widespread decreases in sunlight resulting from increasing cloud coverage and aerosol concentration."

What it means
Based on this finding and assuming the data used to derive it are correct, either (1) the general expectation that global warming should lead to significantly increased pan evaporation is wrong or (2) there was little to no net warming over the period 1960-1990.

Each of these alternatives tends to undercut the conceptual foundation for climate-alarmist claims of significant CO2-induced global warming over this period; for they suggest the existence of fundamental deficiencies in our understanding of either (1) basic meteorological phenomena, as in the first case, or (2) the temperature history of the earth, as in the second case.

[Number_Cruncher]

Fred Singer stated: "Geophysical historical data do not support the claim that a warmer planet would be catastrophic. Studies of tree rings, ice cores and ocean sediment cores indicate that the Earth's temperature was considerably warmer than today at 1,000, 3,000 and 6,000 years ago. Global temperature changes, as rapid and large as those forecasted by climate models, have occurred in the past with no detrimental effects." Now pan evaporation is another proxy that may indicate no recent warming. Earlier this week, the change in species distribution was reported as 3.8 miles/decade, equivalent to a change in global temperatures of 0.025 C/decade.

The following times series indicate little or no recent warming: 1) MSU satellite, 2) balloon thermistors, 3) balloon pressure transducers, 4) pan evaporation, 5) species movement, 6) tree rings, 7) ice cores, and 8) ocean sediment cores. The odd man out is surface measurements that indicate a warming, but these measurements are poor (see, for example, http://www.webace.com.au/~wsh/)

[Celtjew Libertarian]

Bump for later read.

[Uncle Miltie]

Environmentalism is a Religion. You don't expect them to rely on science like this, do you?

[larryjohnson]

I have to bookmark this in order to bookmark all the bookmarks you have on your profile page. I am retired with meteoroogy and aerospace engineering degrees. Retired but I don't seem to have the time to read up on this topic. Tell me your interest.Better yet tell us about yourself on your profile. Fred Singer and his site are favs of mine as voices of scientific reason and logic and we have emailed.

[PeaceBeWithYou]

Ping.

[Ernest_at_the_Beach]

Thanks for the ping!

Thanks for posting this - Number_Cruncher.

Global Warming Hoax :

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[Free the USA]

thanks for the ping

[Number_Cruncher]

More on the lack of warming here: http://www.sepp.org/NewSEPP/tempratureTrends-Singer.htm

Key quote: "We have been examining some dozen published proxy records that show temperatures beyond 1980. So far none show a warming since 1980. Contrary evidence is often cited: shrinking of mountain glaciers and of Arctic sea ice; warming of the deep ocean; rise in sea level during the 20th century. All of these observations can be accounted for in terms of the delayed effects of a previous natural warming and thus not necessarily due to any human influence."