I: 2 degrees Celsius, or 3.6 degrees Fahrenheit. Industrialized countries hope they can limit global warming to that figure. We asked NPR's Richard Harris to look at how scientists arrived at that number in the first place.</s>RICHARD HARRIS: In 1992, the nations of the world signed onto a treaty in which they agreed to prevent dangerous interference with the earth's climate. There's no easy way to define dangerous, but scientists like Michael Oppenheimer at Princeton began thinking about how much delicate ecosystems like coral reefs and human systems like agriculture could tolerate.</s>MICHAEL OPPENHEIMER: And ultimately, numbers in the range of 2 degrees Celsius began to surface.</s>RICHARD HARRIS: Studies over the years kept coming back to that number. So the European Union decided to adopt 2 degrees as its climate-change limit. Earlier this year, most of the other industrialized countries, including the United States adopted it as well. End of story? Not quite.</s>MICHAEL OPPENHEIMER: There's a new concern over the last five years or so with the ice sheets.</s>RICHARD HARRIS: Greenland and Antarctica might start to melt rapidly, even at 2 degrees of warming, pushing sea level up as much as six feet this century and more after that. Also, African delegates in Copenhagen are none too happy with the 2-degree goal. Lumumba Di-Aping from Sudan says if the globe warms 2 degrees on average, Africa would heat up by substantially more. Di-Aping says that would turn Africa into a furnace.</s>LUMUMBA DI: Two degrees is a certain death for Africa.</s>RICHARD HARRIS: Richard Harris, NPR News.
The industrial world has set a goal of preventing the global average temperature from rising more than 2 degrees Celsius, that's 3.6 Fahrenheit, above preindustrial levels. That number will be discussed a lot during the global warming talks in Copenhagen.