W
hy has the warming trend slowed?
Climatologists aren't sure. What they do know is that the average air temperatures at the earth's surface have risen only about 0.2 degrees Fahrenheit since 1998 — the hottest year of the 20th century — even as humanity has continued to pour vast quantities of carbon dioxide and other greenhouse gases into the atmosphere. The world pumped roughly 110 billion tons of CO2 into the air between 2000 and 2010 — about a quarter of the total put there by mankind since the start of the Industrial Revolution. According to the prevailing models of man-made climate change, greenhouse gases heat the planet by trapping solar radiation in the atmosphere that might otherwise radiate into space. So the additional emissions over the past decade should have caused average temperatures to continue to climb as steeply as they did in the 1980s and 1990s. Climate-change skeptics say the plateau in warming proves that the climate isn't as sensitive to greenhouse emissions as scientists claim, and that it would therefore be foolish to adopt costly measures to limit the use of fossil fuels that emit CO2. "There is no problem with global warming," said Ian Plimer, an earth sciences professor at Australia's University of Melbourne. "It stopped in 1998."
Climatologists aren't sure. What they do know is that the average air temperatures at the earth's surface have risen only about 0.2 degrees Fahrenheit since 1998 — the hottest year of the 20th century — even as humanity has continued to pour vast quantities of carbon dioxide and other greenhouse gases into the atmosphere. The world pumped roughly 110 billion tons of CO2 into the air between 2000 and 2010 — about a quarter of the total put there by mankind since the start of the Industrial Revolution. According to the prevailing models of man-made climate change, greenhouse gases heat the planet by trapping solar radiation in the atmosphere that might otherwise radiate into space. So the additional emissions over the past decade should have caused average temperatures to continue to climb as steeply as they did in the 1980s and 1990s. Climate-change skeptics say the plateau in warming proves that the climate isn't as sensitive to greenhouse emissions as scientists claim, and that it would therefore be foolish to adopt costly measures to limit the use of fossil fuels that emit CO2. "There is no problem with global warming," said Ian Plimer, an earth sciences professor at Australia's University of Melbourne. "It stopped in 1998."
Do climate scientists agree?
No. They concede that temperatures haven't risen as rapidly as they did in the previous two decades, but say the world is still getting warmer due to man-made emissions. Despite the plateau in average temperatures, climatologists point out, the 2000s were hotter than the 1990s, and nine of the 10 warmest years on record have occurred since 1998. Overall, the world has warmed by 1.4 degrees Fahrenheit, which sounds modest, but is a tremendous amount of heat for the entire surface of the earth, already causing major melting of the polar ice caps and noticeably more extreme weather throughout the world. Still, that doesn't explain what happened to the "missing heat" — the warmth the last decade's greenhouse gas emissions should have trapped in the atmosphere.
No. They concede that temperatures haven't risen as rapidly as they did in the previous two decades, but say the world is still getting warmer due to man-made emissions. Despite the plateau in average temperatures, climatologists point out, the 2000s were hotter than the 1990s, and nine of the 10 warmest years on record have occurred since 1998. Overall, the world has warmed by 1.4 degrees Fahrenheit, which sounds modest, but is a tremendous amount of heat for the entire surface of the earth, already causing major melting of the polar ice caps and noticeably more extreme weather throughout the world. Still, that doesn't explain what happened to the "missing heat" — the warmth the last decade's greenhouse gas emissions should have trapped in the atmosphere.
1 comment:
Average global temperature history since 1975 is like a hill. We went up the hill from 1975 to 2001 where the average global temperature trend reached a plateau (per the average of the five government agencies that publicly report average global temperature anomalies). The average global temperature trend since 2001 has been flat to slightly declining but is on the plateau at the top of the hill. Claiming that the hill is highest at its top is not very profound. The temperature trend has started to decline but the decline will be slow; about 0.1 K per decade for the planet, approximately twice that fast for land areas.
GW ended before 2001. http://endofgw.blogspot.com/
AGW never was. http://climatechange90.blogspot.com/2013/05/natural-climate-change-has-been.html
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