Cause of global warming is still debated
Published Feb. 9, 2007
In 1988, the World Meteorological Organization and the United Nations Environment Programme created the Intergovernmental Panel on Climate Change to assess the problem of global climate change, more popularly known as global warming.
The IPCC released the first section summary for policymakers of its fourth report on Feb. 2. The last full report was released in 2001. This section is the first of four to be released and deals mainly with the physical science of the problem, said Kristen Averyt, project member of IPCC Working Group 1. It will be released in its completion this spring.
"Hopefully, the information in the document will allow policy makers to make informed decisions about public policy," she said.
The report's authors, comprised of more than 1,000 scientists from more than 60 countries, reaffirmed that the global climate is indeed changing. They concluded that global warming is occurring with a 90 percent chance that humans are responsible, Averyt said.
The next sections of the report will deal with the impact of climate change, humans' vulnerability and reducing the phenomenon's negative impacts.
MU professor of atmospheric sciences Tony Lupo was a reviewer of the report's summary and contributed writings for the second IPCC conference's report. Although Lupo agrees temperatures are indeed rising throughout the globe, he does not think it can necessarily be attributed to humans yet.
"There is not enough evidence to blame humans," Lupo said. "Given the knowledge and data we have now, it is impossible to find the human contribution to climate change."
But the summary released by the IPCC has a much different tone.
"The observed widespread warming of the atmosphere and ocean, together with ice mass loss, support the conclusion that it is extremely unlikely that global climate change of the past fifty years can be explained without external forcing and very likely that it is not due to known natural causes alone," the report states.
Lupo said one of the main things scientists examined at the conference is the rise in carbon dioxide levels in the atmosphere. This is also one of the main arguments used to support the assertion that humans are causing climate change.
"Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years," the report states.
But Lupo said carbon dioxide alone cannot explain climate change.
"On a time scale of centuries or millennia, there's a very strong correlation between carbon dioxide and heat," he said. "But on a time scale of decades, the correlation is more tenuous."
Lupo said throughout the earth's history, there have been many instances of climate change, including periods of increased warming that melted parts of the polar ice caps. He cited numerous other factors that could play a part in climate change, including solar fluctuations, lack of volcanic activity and oceans releasing heat.
Based on the current model, global warming will begin to strongly affect humans by the middle of the century, Lupo said.
"There's a broad spectrum of opinion out there from 'game over' to 'if we are causing it, we should do more because carbon dioxide is good for plants,'" Lupo said.
Lupo said he thinks the action the government takes will depend on whether the Democrats win the elections in 2008.
The IPCC will release the second section of its report after the panel meets in Brussels, Belgium, in April.
