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April 9, 2007

Climate Change

A Warming Planet

UN panel warns of broad, catastrophic disruptions if greenhouse gases rise unabated

Bette Hileman

On April 6, a United Nations panel outlined broad, eventually catastrophic changes in the planet that will occur if emissions of greenhouse gases are not curbed. As global temperatures continue to rise, species extinctions will increase, water shortages will spread, and droughts and floods will become much more widespread, warned the Intergovernmental Panel on Climate Change (IPCC) in its report on impacts.

The areas of the world most vulnerable to the impacts of a warming planet are the Arctic; sub-Saharan Africa; small island states; and the large, highly populated river deltas of Asia, says the report, which was prepared by the IPCC's Working Group II.

"It is the poorest of the poor people in the world, even the poorest in the most prosperous nations, who are going to be the worst hit and are the most vulnerable, as far as the impacts of climate change are concerned," IPCC Chairman Rajendra K. Pachauri said at a news conference in Brussels. "This certainly requires attention because people who are poor are least able to adapt to the impacts."

"At the global level, there is a man-made climate signal coming through on plants, animals, water, and ice," said Martin Parry, cochair of Working Group II. "For the first time, we are no longer arm-waving with models, saying this might happen. This is empirical information on the ground. When put together, 29,000 data sets provide a picture of the impacts of climate change around the world," he explained.

Furthermore, Parry said, future impacts can now be estimated more systematically and for a greater range of sectors and regions. As temperatures increase, there will be greater water availability in the areas where it is already moist and widening droughts in the low-latitude, semiarid regions, such as sub-Saharan Africa, the American Southwest, and the Middle East, he said. "It is exactly what we don't want. It makes the world more inequitable."

With a small amount of warming, Parry continued, food production will increase at high latitudes and decrease at low latitudes. But if temperatures rise about 3 oC from the 1980-99 average, "you get a global downturn in agricultural productivity," and 40% of the species around the globe will become extinct, he said. With only a 2 oC temperature rise, millions more people will face risk of flood every year, he warned.

The average global temperature has already risen 0.77 °C since 1850, and 0.27 °C from the 1980-99 average. Under current projections with no significant reductions in emissions, global temperatures are expected to rise 2 °C by the 2050s and 3 °C by the 2070s from the 1980-99 average.

The 1,572-page report was prepared by more than 200 scientists, and the summary of the report was approved by officials from 120 countries. It will be discussed at the upcoming meeting of the Group of Eight industrial nations in June. There, the European Union is expected to try to convince the U.S. to make stronger efforts to cut carbon dioxide emissions.

In an April 6 press briefing about the report, James L. Connaughton, chairman of the White House Council on Environmental Quality, insisted that the U.S. is taking action on climate change even though it has not ratified the Kyoto protocol. "We are leading the way with actually dozens of advanced technology partnerships," he said.

Impacts of warming rise with rising global temperatures
0-1 °C 1-2 °C 2-3 °C 3-4 °C 4-5 °C
Increased water stress for hundreds of millions of people Up to 30% of species at risk of extinction     More than 40% of species extinct
Increasing wildfire risk Most corals bleached Widespread coral mortality 30% of global wetlands lost Global economic losses up to 5% of GDP
Increased sickness and mortality from heat waves, floods, and drought Cereal productivity tends to decrease at low latitudes   Cereal productivity goes down almost everywhere  
      40% of biosphere becomes a net carbon source  

NOTES: Temperature rise is relative to the 1980 to 1999 global average.?? All of the impacts increase with rising temperatures.

SOURCE: Intergovernmental Panel on Climate Change

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