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Sierra magazine
The Enemy of the Human Race

By James Hansen

When the history of global warming is written--hopefully in a cooler and saner future--climatologist James Hansen will likely be credited as the first to have sounded the alarm. In 1988, on a hot and muggy June day, he testified to Congress that humans were almost certainly responsible for raising worldwide temperatures. He was (and remains) in a position to know: NASA's Goddard Institute for Space Studies, which he heads, monitors temperatures at thousands of sites around the world and has documented an average increase of more than one degree since 1970.

Since his initial warning, Hansen has continued to ring the bell as loudly and forcefully as he can. This landed him in trouble with the George W. Bush administration, which in 2005 clumsily attempted to ban him from commenting publicly on climate change. Hansen continued to speak out. Recently he has focused his efforts on winning a worldwide moratorium on burning coal. Last December he and his wife, Anniek, made their plea directly to Barack and Michelle Obama. The following is an adaptation of that letter.

There are long lists of things people can do to mitigate climate change. But the sine qua non for solving the problem is to stop burning coal. Coal is responsible for as much atmospheric carbon dioxide as all other fossil fuels combined and is even more of a long-term threat given the earth's enormous coal reserves. (Oil, the second-greatest contributor to atmospheric carbon dioxide, is already substantially depleted.) The safe upper limit for atmospheric CO2 is 350 parts per million. We are currently at 385 ppm. Continued reliance on coal-fired power plants will raise atmospheric carbon dioxide to nearly 500 ppm. At that level, a conservative estimate for the number of species that would be exterminated is one million. Coal plants are factories of death.

The world must end coal emissions rapidly, through a moratorium on new coal-fired power plants and a phaseout of those that do not capture and store carbon dioxide (no commercial plants do at present). This is a great challenge but one with enormous side benefits, including reduced local pollution and a sharp decrease in the toxic mercury (a byproduct of coal-fired power plants) that is now accumulating in fish stocks throughout the oceans. If coal emissions are promptly phased out, other actions--for example, improved agricultural and forestry practices--could bring the level of atmospheric carbon dioxide out of the dangerous range and save the planet we know--the planet of stable climate in which civilization developed.

Photo: iStockphoto/Kngkyle2

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