food for thought

From: Reuters, Sept. 27, 2007
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Reuters, September 27, 2007

U.N. CLIMATE PANEL REPORT'S KEY FINDINGS

[Rachel's introduction: Here is a concise summary of the findings of the Feb., 2007, report from the U.N.'s Intergovernmental Panel on Climate Change (IPCC), representing the work of 2,500 researchers from more than 130 nations.]

Here are the key findings on climate change from a February 2, 2007 report by the U.N. Intergovernmental Panel on Climate Change, which represents the work of 2,500 researchers from more than 130 nations.

Evidence Of Human Causes

** "Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (human) greenhouse gas concentrations," it says. The IPCC says "very likely" means at least a 90-percent probability.

** "The level of confidence that humans are causing global warming has increased a lot," report author Peter Stott said.

Temperature Increases

** It is very likely that extremes such as heat waves and heavy rains will become more frequent.

** "For the first time we have a best estimate of what we can achieve if we keep emissions levels lower," said report chair Susan Solomon.

** The report does not include possible warming from methane, a potent greenhouse gas, escaping from melting permafrost.

** Warming is expected to be greatest over land and at high northern latitudes, and least over the Southern Ocean and North Atlantic.

Sea Level Rises

** The report cites six models with core projections of sea level rises ranging from 7.2 to 23.6 inches this century. That is a narrower and lower band than the 3.5 to 34.6 inch gain forecast in 2001.

** If the Greenland ice sheet melts proportionally to the temperature increases, then sea levels would rise by up to 31.6 inches this century.

** Some models show an ice-free Arctic in summer by 2100, meaning that sea ice floating in the water disappears, but not ice resting on Greenland.

** If the Greenland ice sheet melted completely, that would lead to a 23.1-foot (7-metre) sea level increase.

Changing Ocean Currents

** The report predicts a gradual slowdown this century in ocean currents such as the one that carries warm water to northwest Europe.

** "It's very unlikely there will be an abrupt breakdown in ocean currents in the 21st century," said Jurgen Willebrand, the report's author with special expertise in ocean effects.

Hurricanes

** The report says it is "more likely than not" that a trend of increasing intense tropical cyclones and hurricanes has a human cause.

** It predicts such tropical cyclones will become more intense in the future.

** "There may not be an increase in number, there may be a redistribution to more intense events -- which is what has been observed in the Atlantic since 1970," Stott said.

Copyright Reuters 2007