The Earth is warming--that's a fact. Burning fossil fuels raises atmospheric CO2-concentrations--that's a fact, too. But that anthropologically elevated CO2-levels contribute to global warming--that's a religious question. Or so it has long seemed to be.

The Intergovernmental Panel on Climate Change (IPCC), the most authoritative body on global warming, has now concluded that humans "contributed substantially to the observed warming over the last 50 years." This is a big change from their last report, published in 1995, that said "the balance of evidence suggests a discernible human influence on global climate."

The panel also warns that temperatures could rise even higher than previously predicted if emissions of so-called greenhouse gases such as CO2 were not curbed. Estimated temperature increases over the next 100 years are between three and 11 degrees Fahrenheit. This upper bound is up from 6.3 degrees estimated in the last report in 1995. In comparison, current temperatures are only nine degrees Fahrenheit warmer than at the end of the last Ice Age thousands of years ago, but it is not necessary to look at the worst-case scenario. Even the lower bound of three degrees Fahrenheit would be the fastest warming over the course of human civilization.

The report's conclusion is even more striking, considering the process by which it was reached. The IPCC is a consortium of hundreds of scientists comprised of outspoken environmentalists as well as industry representatives. One of these critics of global warming is Dr. Richard S. Lindzen '60, Alfred P. Sloan Professor of Meteorology at MIT. Often described as a champion to political conservatives and industrial interests, he has become famous for statements such as "we don't have any evidence that [global warming] is a serious problem." On the basis of his own climate model, Lindzen has so far argued that CO2 does not contribute to global warming. Now, however, he helped write one chapter of the 1000-page assessment, and was recently quoted as saying that "there has to be a human component to the change that's under way."

Lindzen still maintains the argument that there is little solid evidence that climate change would have harmful effects. This statement, however, can be easily discredited simply because it falls outside his area of expertise. As a meteorologist, Lindzen could back his previous argument that global warming did not exist by his own well-documented climate model. Determining the effects of global warming, however, falls in the realm of ecologists who almost all agree that climate change at this unprecedented rate in recent history will have negative effects on our flora and fauna. As a statement signed by 2,500 economists--among them eight Nobel prize laureates--suggests, the economic community at large also believes that climate change will have negative effects on our economy. Although the summary of the IPCC assessment itself acknowledged the need for further research, it did not fail to mention the many negative consequences due to global warming, even if it follows the middle path as predicted in the report.

Especially in the light of the upcoming climate summit in The Hague later this month, it is finally time for Congress to face this reality. The climate meeting next month will bring together representatives of roughly 150 countries with the goal of working out further details of the Kyoto Protocol which they all signed in 1997. The protocol, however, has not been ratified by any industrialized country. Many European countries have made their ratification dependent on the decision reached in the U.S. Congress, since they feel they should not have to agree to cut emissions if the biggest polluter in the world does not agree to do so as well. The Republican Congress and Texas Gov. George W. Bush, on the other hand, do not want to sign the treaty since it excludes many developing countries, including India and China. They are right that excluding India and China from the treaty exempts the world's two most populous nations from contributing to the reduction of global CO2-emissions. The ultimate goal must be to include all developed and developing countries in a joint effort to curb the world's greenhouse gas emissions, but this cannot happen without U.S. leadership.

The new IPCC assessment clearly states that humans contribute to global warming. Let's face that reality and take the next logical step of ratifying the Kyoto protocol.