PARIS, France (AP) -- The world's leading climate scientists said global warming is "very likely" (99 percent chance) man-made, according to a new 20-page report obtained Friday by The Associated Press.
Human-caused warming and rises in sea-level "would continue for centuries" because the process has already started, even if greenhouse gas concentrations were to be stabilized. The report by a group of hundreds of scientists and representatives of 113 governments contains the most authoritative science on the issue
On sea levels, the report projects rises of 7-23 inches by the end of the century. That could be augmented by an additional 4-8 inches if recent surprising polar ice sheet melt continues. The 2001 report projected a sea level rise of up to 35 inches. Many scientists had warned that this was being too cautious and said sea level rise could be closer to 3 to 5 feet (150cm) because of ice sheet melt.
Rising sea levels and stronger hurricanes
The panel quickly agreed Thursday on two of the most contentious issues: attributing global warming to man-made burning of fossil fuels and connecting it to a recent increase in stronger hurricanes. Negotiations over a final third difficult issue -- how much sea level rise is predicted by 2100 -- went into the night Thursday with a deadline approaching for the report
"I hope that policymakers will be quite convinced by this message," said Riibeta Abeta, a delegate whose island nation Kiribati is threatened by rising seas. "The purpose is to get them moving."
Meanwhile, the U.S. government delegation was not one of the more vocal groups in the debate over whether warming is man-made, said other countries' officials. And several attendees credited the head of the panel session, Susan Solomon, a top U.S. government climate scientist, with pushing through the agreement so quickly.
The Bush administration acknowledges that global warming is man-made and a problem that must be dealt with, Bush science adviser John Marburger has said. However, Bush continues to reject mandatory limits on so-called "greenhouse" gases, even as he acknowledges the existence of climate change.
1. Introduction The greenhouse effect is responsible for the Earth's warm, livable atmosphere. Gases like methane and carbon dioxide trap heat near the surface, keeping the Earth about 33 C (60 F) warmer than it would be without its natural blanket of protective gas. The greenhouse effect is a natural phenomenon, but human activity can enhance its effect and destabilize the climate.
2. Gases Water vapor, methane, carbon dioxide, CFCs, ozone and nitrous oxide are all greenhouse gases (GHGs). Carbon dioxide (CO2) is the most important, followed in descending order by methane, CFCs, ozone and nitrous oxide. Climate scientists say human activities that pour enormous volumes of these gases into the atmosphere are raising the planet's temperature.
3. Sun The sun sends energy toward Earth in the form of light and radiation. We experience solar radiation as light and warmth on a sunny day.
4. Atmosphere When the sun's rays strike the atmosphere, some of the radiation is immediately reflected into space. The radiation that gets through the atmosphere heads toward the Earth's surface.
5. Earth Solar radiation that passes through the Earth's clear atmosphere is absorbed by the ground, water, plants and other objects. As the sun warms objects, they emit infrared radiation. This is the energy we know as heat. A portion of the solar radiation that reaches the Earth's surface -- particularly areas covered by ice, snow or the ocean -- also bounces back into space, where its heat energy dissipates.
6. Heat and gasesMolecules of greenhouse gases in the atmosphere absorb infrared radiation and release heat, which raises the temperature of the ground and air and warms the Earth's surface. Infrared radiation has a longer wavelength than visible light, so it is easier for molecules like carbon dioxide and water vapor to absorb energy and trap the sun's energy beneath Earth's atmosphere.
7. Into space Some infrared radiation continues on its path out of the atmosphere and into space. The energy the sun sends to the entire Earth averaged over a whole year is roughly 343 watts per square meter. When that energy hits the Earth's surface, some of it is absorbed and some of it is reflected back into the atmosphere. The net outgoing energy -- that is, radiation that goes back into space -- is 240 of the original 343 watts per square meter
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