A new study out of Germany casts further doubt on the so-called global warming “consensus” by suggesting the atmosphere may be less sensitive to increases in carbon dioxide emissions than most scientists think.
A study by scientists at Germany’s Max Planck Institute for Meteorology found that man-made aerosols had a much smaller cooling effect on the atmosphere during the 20th Century than was previously thought. Why is this big news? It means increases in carbon dioxide emissions likely cause less warming than most climate models suggest.
What do aerosols have to do with anything? Well, aerosols are created from human activities like burning coal, driving cars or from fires. There are also natural aerosols like clouds and fog. Aerosols tend to reflect solar energy back into space, giving them a cooling effect that somewhat offsets warming from increased CO2 emissions.
The Max Planck study suggests “that aerosol radiative forcing is less negative and more certain than is commonly believed.” In layman’s terms, aerosols are offsetting less global warming than was previously thought. And if aerosols aren’t causing as much cooling, it must mean carbon dioxide must be causing less warming than climate models predict.
“Going forward we should expect less warming from future greenhouse gas emissions than climate models are projecting,” write climate scientists Pat Michaels and Chip Knappenberger with the libertarian Cato Institute, adding that this study could be a “death blow” to global warming hysteria.
Independent climate researcher Nick Lewis put out a study last year with Georgia Tech’s Dr. Judith Curry which found that the climate’s response to a doubling of atmospheric CO2 levels — a measurement called “climate sensitivity” was 1.64 degrees Celsius.
Lewis revised his findings based on the Max Planck aerosol study and found something astounding: climate sensitivity drops dramatically. Lewis also looked at climate sensitivity estimates given by the Intergovernmental Panel on Climate Change — often regarded as the world’s top authority on global warming.
The IPCC’s latest assessment put climate sensitivity between 1.5 and 4.5 degrees Celsius. The IPCC says that despite “the large uncertainty range, there is a high confidence that aerosols have offset a substantial portion of [greenhouse gas] global mean forcing.”
Basically, the IPCC says aerosols deflect a lot of warming — the opposite of the Max Planck study’s finding. Continue reading