Friday, March 8, 2002
Earth's climate in peril
Finally, a definitive scientific report, agreed to by 99.9% of the world's top 1000 climatologists, has been published on the effects of humans on the climate. The conclusions are grim: mankind is adversely affecting the environment in dramatic fashion. Global temperature is going to rise between 5 and 10 degrees F in this century, a tremendous amount in such a relatively short period of time. Exactly how much within this range depends on how much the world can reduce greenhouse gas emissions.
The Intergovernmental Panel on Climate Change (IPCC), a United Nations sponsored group of 600 climatologists from 70 countries, spent the last four years writing a comprehensive report, "Climate Change 2001: Impacts, Adaptation, and Vulnerability." The report, verified by the US National Academy of Sciences, summarizes hundreds of scientific articles in peer-reviewed journals that indicate a correlation between burning of fossil fuels, global warming, and negative effects on the environment. Dr. James McCarthy, Harvard professor and co-chair of the IPCC, presented a sobering outlook for the environment as The Concord Land Conservation Trust kicked off its 2002 Environmental Lecture Series at the CCHS auditorium on Feb. 11. The rest of this article summarizes Dr. McCarthy's talk on global climate change as documented in the IPCC report.
Graphs of worldwide concentrations of two common greenhouse gases, carbon dioxide and methane, show a dramatic increase in the last 20 years. A corresponding rise in global temperatures has been measured using records dating back to 1860. Tree ring studies and ice core samples provide baseline measurements of greenhouse gas concentrations and air temperature over the last 1000 years, further indicating a drastic change occurring over just the last two decades. Natural causes for temperature change such as volcanoes (volcanic gas and dust reflect sunlight, causing cooling) and variation in solar luminance (due to sunspots and other solar activity) have been measured and modeled, but they do not account for the recent increase in global warming. The conclusion is that over half of the recent warming is due to human activity.
The IPCC report states that both physical and biological systems have been affected by climate change, especially temperature rise. Insurance costs of extreme weather events have increased by a factor of 10 since 1950, adjusted for inflation. The sea level has risen over the last century, resulting in coastal flooding worldwide. Tropical storms have increased peak winds and precipitation. El Nino events in the Pacific are associated with increased droughts and floods. (Droughts can cause floods to be worse because water runs off very dry soil.) Asian summer monsoons have been increasing in variability. Record floods have occurred in China, India, and Africa in the last five years. The duration of ice cover on rivers and lakes in mid to high latitudes has decreased by two weeks over the last 100 years. Arctic sea ice has decreased in area by 10-15 percent, and in thickness by 40 percent, in the last 50 years. Species redistribution, such as bird migration patterns, has been in concert with regional temperature changes. The polar bear is in danger, and other species are going extinct. In 20-30 years, there will be no glaciers in Glacier National Park. Warming of the ocean is causing coral bleaching and destruction. The Gulf Stream itself may shut down because it relies on the sinking of cold, briny water in northern latitudes to create circulation.
Dr. McCarthy concludes with some things that individuals can do today to help avert a crisis. Companies that publicly voice some concern for the environment, such as BP, Amoco, Shell, Alcoa, and Dupont, deserve support some other companies, such as Exxon and Mobil, still publish ads ignoring recent scientific conclusions. Politicians, who are often unaware of the public's concern for the environment, give much more attention to written letters than to e-mail. More and more car companies are producing fuel-efficient hybrids in response to increasing demand by consumers who realize that automobiles are the biggest way that individuals generate air pollution.
© 2002 The Carlisle Mosquito