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Climate 'out of balance,' prof says on Earth Day

Anita Weier  —  4/23/2008 11:57 am

Human beings have changed the composition of the air itself — the global atmosphere — and something has to be done about it, UW-Madison professor Jonathan Foley told the state Natural Resources Board Tuesday on Earth Day.

"Between 1950 and 2000, the world population more than doubled. The economy grew sevenfold. Food consumption almost tripled. Water use roughly tripled. Fossil fuel use increased fourfold," Foley said. "The planet started to notice."

A long-term rise of carbon dioxide, methane and nitrous oxide — mainly due to the burning of coal, oil and natural gas — warmed the Earth, he said.

Those heat-trapping gases multiplied what is a natural greenhouse effect, in which the sun heats the Earth and the Earth in turn gives off radiation in infrared waves. Those waves go into the atmosphere, which absorbs some of that heat and radiates it back down to Earth.

"The Earth is 30 degrees warmer than it would be without that natural greenhouse effect. Without it, life would never have evolved," Foley said.

But humans made the greenhouse a little thicker by burning fossil fuels.

"It's like putting an extra blanket on your bed in the winter. We warm the Earth's surface a little more. It's throwing our whole climate out of balance. It is a human-caused disturbance on a natural process," said Foley, founder and director of the Center for Sustainability and the Global Environment at the University of Wisconsin-Madison.

During the 20th century the average temperature of the planet rose by 1 degree centigrade.

"It takes a lot to change this. It was only 3 degrees colder in the last ice age," Foley said. "Ten of the warmest years on record were all in the last 15 years, and 2005 was probably the warmest ever."

Temperature records were set all over the United States in July 2006, and Wisconsin had its record warmest 12 months from July 2005 through June 2006."

Droughts, extremely heavy rains and flooding also have been caused by global warming, he said, as the cycle of rainfall and evaporation changes. Wisconsin has had drought conditions in the north and heavy rains in the south in recent years. Glaciers are melting and sea ice in oceans has shrunk in the summers.

"We have lost in two years an area of sea ice as large as the United States east of the Mississippi," he said.

Foley also reminded his listeners — including a packed room at DNR headquarters as well as the Natural Resources Board — that weather is more unpredictable than climate, and that a cold, long winter is not a sign that global warming is going away. Maximum temperatures have crept up, but cold temperatures have gotten much warmer, he said. Wisconsin winters now have very few below-zero days, and summers have few over 90-degree days, Foley added.

"We have very clear evidence of global warming, not only a smoking gun. We have the DNA evidence, the knife and the footprints," he said.

Though skeptics still contend that global warming does not exist or that it's not due to people, they do not have the data to prove it, Foley added.

"The scientists are absolutely sure. There is not an international debate. A handful of professional climate skeptics like to get on TV, but that doesn't make their science right. Of 928 papers published with data about climate change in the last 10 years, zero have said climate change is not happening," he said.

And the problem will worsen, unless drastic action is taken now, because the CO2 that we continue to put into the atmosphere lasts a long time. Even if we stopped burning fossil fuel now, the climate would continue to warm for 30 to 50 years, according to Foley.

Anita Weier  —  4/23/2008 11:57 am