IPCC Reduces Global Warming Projections

Published April 1, 2007

On February 2, the Intergovernmental Panel on Climate Change (IPCC) released the Summary for Policymakers of its Fourth Assessment, even though the full report will not be released for three months. The summary claims there is an increasing likelihood that humans are causing a warming of the climate, but it also predicts less global warming than was forecast by previous IPCC reports.

The U.S. Senate Energy and Natural Resources Committee, chaired by Sen. Barbara Boxer (D-CA), held a series of hearings on climate change in January and February. The U.S. House Science and Technology Committee, chaired by Rep. Bart Gordon (D-TN), conducted a full committee hearing on climate change on February 8, specifically addressing the release of the IPCC summary.

“Congress is holding hearings on a theory which has no evidence to support it, and ignoring the evidence that mostly all of the recent warming is part of a natural cycle that is not dangerous and is unstoppable,” said Dennis Avery, director of the Center for Global Food Issues and a senior fellow at the Hudson Institute.

“Instead of addressing real problems, Congress is occupying itself with elaborate hearings on global warming and with fabricating outlandish schemes of controlling the emission of carbon dioxide (read: the use of energy),” agreed Dr. S. Fred Singer, president of the Science and Environmental Policy Project. “All these schemes are quite ineffective in reducing the global growth of atmospheric CO2–never mind in having any effect on climate. The schemes do have one thing in common: They will damage the U.S. economy and hurt the pocketbooks of every consumer of energy–the folks who drive cars, heat their homes, and pay electric bills.”

Avery and Singer are the coauthors of Unstoppable Global Warming Every 1,500 Years, which was #24 on the New York Times best-seller list in early March.

Science Revised to Fit Summary

The 18-page IPCC Summary was formally approved at the 10th session of Working Group I in Paris. The work is the product of 33 drafting authors and 18 draft contributing authors.

The study authors were representatives of governments, not the scientists who produced the data. Prior to release of the Fourth Assessment in May, IPCC scientists will have to revise their scientific assessments to comport with the assertions made by the nonscientists in the Summary.

“The Summary for Policymakers is designed to be a propaganda document that will promote global warming alarmism. It is not written by the scientists who wrote the report, but by the governments that belong to the IPCC,” said Myron Ebell, director of energy and global warming policy at the Competitive Enterprise Institute.

The IPCC has published three “assessments” of climate change; the first in 1990, one in 1995, and another in 2001.

Less Warming Predicted

The new Summary states most of the observed warming “since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” Scientific measurements confirm that since the mid-20th century the planet cooled for 30 years and then warmed for 30 years.

Despite the Summary’s assertion that the human influence is driving much of the recent warming, the document presents a far less alarmist view of potential warming scenarios than was presented in the IPCC’s 2001 Third Assessment.

The new Summary’s middle-of-the-road projection is for a roughly 2.5º C increase in temperatures by the end of the twenty-first century. This is down from the Third Assessment’s projected 3.0º C temperature rise.

Additionally, the “worst-case” scenarios have also been toned down. The Third Assessment projected a 5.8º C rise in temperatures as a worst-case scenario, while the new Summary projects a 4.5º C worst-case scenario.

Small Sea Level Change

The Summary suggests sea level will increase between 7 and 23 inches by the end of the century, with “best estimates” calling for roughly 13 inches. This estimate is also a significant downward revision from the Third Assessment, which projected a worst-case sea level rise of 3 feet.

The document estimates there will be a loss of ice in Greenland, but that the “Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.”

The Summary further states there is no scientific link between global warming and severe weather events such as tornadoes, refuting assertions made by global warming alarmists and in Al Gore’s movie An Inconvenient Truth.

Better Data Undermine Alarmism

The document further states that the scientific community has better data than it has had in the past and has made use of this improved data in the new report.

“The IPCC Summary projects less temperature rise and less sea level rise than it did in 2001,” observed Iain Murray, senior fellow with the Competitive Enterprise Institute.

Referring to the complete Fourth Assessment due to be released in May, Murray said, “The underlying science from the full report itself will predict climate change impacts over the next century more modest than previous reports, and far below claims made by organizations and individuals predicting imminent catastrophic changes.”

Michael Coulter ([email protected]) teaches political science at Grove City College.

For more information …

The IPCC’s Summary for Policymakers, released February 2, is available through PolicyBot™, The Heartland Institute’s free online research database. Point your Web browser to http://www.policybot.org and search for document #20737.