It has been a bad week for the environment. On Monday, a United Nations conference unanimously approved a report confirming that the threat of global warming is both real and intensifying. It identified human activity as the chief culprit. If we needed more proof that we are poor stewards of the environment, while the conference was studying the study, a freighter ran aground off the coast of Ecuador, leaking oil that threatened the famous Galapagos Islands with irreparable damage. If we need an image to understand the price of our carelessness -- if the formulas of the U.N. report are too abstract -- the listing, rusting hull of the Jessica serves all too well.

The report approved by the U.N. conference was prepared by the Intergovernmental Panel on Climate Change, a nonpartisan group of hundreds of scientists and experts. The report, the most comprehensive study ever conducted on global warming, was three years in the making and each line was scrutinized by delegates from 100 governments at the U.N. meeting in Shanghai. While it draws on two previous reports, the conclusions of this study -- refined by sophisticated computer analysis -- are frightening.

According to the report, the Earth's average temperature could rise by as much as 5.5 C over the next 100 years -- the most rapid change in 10,000 years. Rising temperatures will melt polar ice caps, which would raise sea levels by as much as 85 cm. Islands and low-lying areas would be flooded. Tens of millions of people would have to move as countries like Bangladesh and Egypt were inundated. Weather phenomena like El Nino would become more common. Temperate zones would shift; farmlands would be hit by drought and new fertile areas would be created. But during the intervening period, hunger is likely to increase worldwide. Diseases would spread.