On global warming, the science is solid
by Andrew Dessler, Katharine Hayhoe, Charles Jackson, Gerald North, André Droxler, and Rong Fu, March 6, 2010In recent months, e-mails stolen from the University of East Anglia's Climatic Research Unit in the United Kingdom and errors in one of the Intergovernmental Panel on Climate Change's reports have caused a flurry of questions about the validity of climate change science.
These issues have led several states, including Texas, to challenge the Environmental Protection Agency's finding that heat-trapping gases like carbon dioxide (also known as greenhouse gases) are a threat to human health.
However, Texas' challenge to the EPA's endangerment finding on carbon dioxide contains very little science. Texas Attorney General Greg Abbott admitted that the state did not consult any climate scientists, including the many here in the state, before putting together the challenge to the EPA. Instead, the footnotes in the document reveal that the state relied mainly on British newspaper articles to make its case.
Contrary to what one might read in newspapers, the science of climate change is strong. Our own work and the immense body of independent research conducted around the world leaves no doubt regarding the following key points:
• • The global climate is changing.
A 1.5-degree Fahrenheit increase in global temperature over the past century has been documented by NASA and the National Oceanic and Atmospheric Administration. Numerous lines of physical evidence around the world, from melting ice sheets and rising sea levels to shifting seasons and earlier onset of spring, provide overwhelming independent confirmation of rising temperatures.
Measurements indicate that the first decade of the 2000s was the warmest on record, followed by the 1990s and the 1980s. And despite the cold and snowy winter we've experienced here in Texas, satellite measurements show that, worldwide, January 2010 was one of the hottest months in that record.
• • Human activities produce heat-trapping gases.
Any time we burn a carbon-containing fuel such as coal or natural gas or oil, it releases carbon dioxide into the air. Carbon dioxide can be measured coming out of the tailpipe of our cars or the smokestacks of our factories. Other heat-trapping gases, such as methane and nitrous oxide, are also produced by agriculture and waste disposal. The effect of these gases on heat energy in the atmosphere is well understood, including factors such as the amplification of the warming by increases in humidity.
• • Heat-trapping gases are very likely responsible for most of the warming observed over the past half century.
There is no question that natural causes, such as changes in energy from the sun, natural cycles and volcanoes, continue to affect temperature today. Human activity has also increased the amounts of tiny, light-scattering particles within the atmosphere. But despite years of intensive observations of the Earth system, no one has been able to propose a credible alternative mechanism that can explain the present-day warming without heat-trapping gases produced by human activities.
• • The higher the levels of heat-trapping gases in the atmosphere, the higher the risk of potentially dangerous consequences for humans and our environment.
A recent federal report, “Global Climate Change Impacts in the United States,” commissioned in 2008 by the George W. Bush administration, presents a clear picture of how climate change is expected to affect our society, our economy and our natural resources. Rising sea levels threaten our coasts; increasing weather variability, including heat waves, droughts, heavy rainfall events and even winter storms, affect our infrastructure, energy and even our health.
The reality of these key points is not just our opinion. The national academies of science of 32 nations, and every major scientific organization in the United States whose members include climate experts, have issued statements endorsing these points. The entire faculty of the Department of Atmospheric Sciences at Texas A&M as well as the Climate System Science group at the University of Texas have issued their own statements endorsing these views (atmo.tamu.edu/weather-and-climate/climate-change-statement; www.ig.utexas.edu/jsg/css/statement.html). In fact, to the best of our knowledge, there are no climate scientists in Texas who disagree with the mainstream view of climate science.
We are all aware of the news reports describing the stolen e-mails from climate scientists and the errors in the IPCC reports. While aspects of climate change impacts have been overstated, none of the errors or allegations of misbehavior undermine the science behind any of the statements made above. In particular, they do not alter the conclusions that humans have taken over from nature as the dominant influence on our climate.
This article was submitted by Andrew Dessler, professor of atmospheric sciences, Texas A&M University; Katharine Hayhoe, research associate professor of atmospheric sciences, Texas Tech University; Charles Jackson, research scientist, Institute for Geophysics, The University of Texas at Austin; Gerald North, distinguished professor of atmospheric sciences, Texas A&M University; André Droxler, professor of earth science and director of the Center for the Study of Environment and Society, Rice University; and Rong Fu, professor, Jackson School of Geosciences, The University of Texas at Austin.
Funny stuff.
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