Global Warming Fears Melting

Global Warming Fears Melting
May 1, 2004

James M. Taylor

James M. Taylor is senior fellow for environment and energy policy at The Heartland Institute, and... (read full bio)

New data from the National Aeronautics and Space Administration (NASA) and studies appearing in two respected scientific journals raise serious questions about the science underlying alarmist predictions of global warming.

NASA: Predictions "Exaggerated"

In the March 13 Journal of Climate, Ken Minschwaner of the New Mexico Institute of Mining and Technology and Andrew Dessler of the University of Maryland reported on atmospheric research they conducted for NASA. Discussing the importance of water vapor assumptions in climate models, they noted, "In most global climate models, an initial warming caused by additional CO2 and other greenhouse gases leads to enhanced evaporation at the surface and a general moistening of the atmosphere. Since water vapor is a strong infrared absorber, the added moisture causes further warming. The amplifying effect can be quite large, increasing the global average warming by 70%-90% compared to calculations that maintain a fixed water vapor."

According to the new NASA data, water evaporation has not increased nearly as much as alarmists have predicted and have factored into their computer models.

As a result, according to the March 18 New York Times, "Dr. Minschwaner said the new research raised questions about the high end" of temperature predictions from the Intergovernmental Panel on Climate Change, which estimates the Earth's climate could warm 2.5 to 10º Fahrenheit in the next century.

According to Environment & Energy Daily, the new data show "predictions about global warming have exaggerated its potential effects."

"Since water vapor is the most important heat-trapping greenhouse gas in our atmosphere," stated a related March 15 NASA press release, "some climate forecasts may be overestimating future temperature increases."

Stated NASA, "In most computer models relative humidity tends to remain fixed at current levels. Models that include water vapor feedback with constant relative humidity predict the Earth's surface will warm nearly twice as much over the next 100 years as models that contain no water vapor feedback."

However, "The increases in water vapor with warmer temperatures are not large enough to maintain a constant relative humidity," NASA quoted Minschwaner as saying.

"These new findings will be useful for testing and improving global climate models," said NASA.

Computer Models Fail Test

Another study, published at the same time as the analysis of new NASA data, also undercut claims that computer models are accurate predictors of future climate.

The study, published in Climate Research (25:185-190), noted that "an important test of model predictive ability and usefulness for impact studies is how well models simulate the observed vertical temperature structure of the troposphere under anthropogenically-induced-change scenarios."

In other words, the predictive accuracy of alarmist computer models can be assessed by feeding past atmospheric data into the models and observing how well the resulting predictions match up with the current climate. "If this predicted feature of global warming is not evident in the real world," stated Sherwood Idso of the Center for the Study of Carbon Dioxide and Global Change, "there is little reason to believe anything else the models predict, including both the cause and (or) magnitude of the observed surface warming."

Importantly, according to the Climate Research study, "at no time, in any model realization, forced or unforced, did any model simulate the presently observed situation of a large and highly significant surface warming accompanied with no warming whatsoever aloft."

Moreover, noted the study, "significant errors in the simulations of globally averaged tropospheric temperature structure indicate likely errors in tropospheric water-vapor content and therefore total greenhouse-gas forcing. Such errors argue for extreme caution in applying simulation results to future climate-change assessment activities and to attribution studies (e.g. Zwiers and Zhang, 2003) and call into question the predictive ability of recent generation model simulations."

New Studies Further Debunk Kilimanjaro

A new study in the March issue of International Journal of Climatology further debunked alarmist claims that global warming is causing a retreat of the famous alpine glacier atop Africa's Mount Kilimanjaro.

Alarmists have recently used the backdrop of Mount Kilimanjaro to gain international media coverage for their predictions of catastrophic human-induced climate change. Showing photographs they claim document a significant decline in Kilimanjaro's snowcap over recent decades, alarmists have used Kilimanjaro as an effective visual-byte for "irrefutable evidence" that significant global warming is occurring.

Senator John McCain (R-Arizona) displayed such before-and-after Kilimanjaro photos in support of his unsuccessful recent attempt to pass a global warming bill in the U.S. Senate. (See "Global Warming Bill Defeated in Senate," Environment & Climate News, November 2003.)

According to the new study, however, reductions in the Kilimanjaro snowpack are due to regional recent dry weather patterns rather than a warming of the atmosphere. The study's authors found no evidence that human factors have played any role in the regional dry spell or any other factor associated with the retreat of the Kilimanjaro glacier.

"Now the pendulum has swung," commented the March 23 New York Times. "The authors wrote that the dry weather both limited the snows that help sustain tropical glaciers and, by reducing cloud cover, allowed more solar energy to bathe the glacier. In dry, cold conditions, the ice vaporized without melting first, a process called sublimation. There was no evidence that rising temperatures had caused the melting."

The International Journal of Climatology study supports the conclusions of other recent studies that have cast doubt on the asserted link between global warming and the retreat of the Kilimanjaro snowpack.

According to a November 24, 2003 article published in Nature magazine, "Although it's tempting to blame the (Kilimanjaro) ice loss on global warming, researchers think that deforestation of the mountain's foothills is the more likely culprit. Without the forests' humidity, previously moisture-laden winds blew dry. No longer replenished with water, the ice is evaporating in the strong equatorial sunshine."

Added S. Fred Singer, professor emeritus of environmental sciences at the University of Virginia and president of the nonprofit Science & Environmental Policy Project in Arlington, Virginia, "Surface measurements of East Africa show no warming trend. Weather satellites show a pronounced cooling trend of the atmosphere there. No one has questioned these data."

"Kilimanjaro turns out to be just another snow job, precipitated by a journalistic community that has lost its desire for critical factual investigation when it comes to our globe's environment," summarized Pat Michaels, research professor of environmental sciences at the University of Virginia and a past president of the American Association of State Climatologists.


James M. Taylor is managing editor of Environment & Climate News. His email address is taylor@heartland.org.

James M. Taylor

James M. Taylor is senior fellow for environment and energy policy at The Heartland Institute, and... (read full bio)