"As the evidence for a large climate sensitivity accumulates and the evidence that it is low evaporates, our society needs to accept the science and begin thinking about what to do about it," says Andrew Dessler. (Credit: Ars Electronica Center/Flickr)

Why Earth might heat up faster than we thought

Climate scientists say previous estimates of how much the planet will warm if the amount of carbon dioxide in the atmosphere doubles—known as climate sensitivity—may be flawed.

“Over the past few years, a debate has raged in the scientific community over climate sensitivity,” says Andrew Dessler, professor of atmospheric sciences at Texas A&M University. “Many researchers found that the 20th-century warming suggested a lower climate sensitivity of about 4 degrees F, while climate models and the paleoclimate record suggested a higher climate sensitivity of 6 degrees F,” Dessler says.

“This difference may not sound like much,” says graduate student John Kummer, lead author of the study published in Geophysical Research Letters. “But it could have a profound effect on the impacts of climate change, such as heat waves, drought, and sea level rise.”

Ozone and aerosols

The researchers calculated climate sensitivity based on the 20th-century warming, but with one key difference.

“Previous estimates have assumed that all human emissions are equally effective at altering the climate,” Kummer says. “However, greenhouse gases like carbon dioxide are well mixed in the atmosphere—this means that, no matter where you go, the amount of carbon dioxide is about the same.

“Ozone and aerosols, on the other hand, have short atmospheric lifetimes, so they are mainly found near where they are emitted. This means that the heating from these constituents are highly localized.  Recent studies using climate models have suggested that this highly localized forcing is more effective at changing the climate.”

“What we did was to take the 20th-century observational record and calculate the climate sensitivity under the assumption that ozone and aerosols were about one-third more effective at warming the climate than well mixed greenhouse gases like carbon dioxide,” Dessler says.

“We found that this yielded a climate sensitivity of 6 degrees F, in good agreement with other estimates of climate sensitivity.”

Dessler is confident that the new method of calculation is an advance over previous calculations.

“We can now resolve the dispute over these different estimates of climate sensitivity,” he says.  “As the evidence for a large climate sensitivity accumulates and the evidence that it is low evaporates, our society needs to accept the science and begin thinking about what to do about it.”

NASA funded the study.

Source: Texas A&M University

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6 Comments

  1. Kris

    This report us absolutely bogus. The weather isn’t warming we just had the coldest winter on record. The don’t say anything about the effects of the Sun on climate change or multiple of factors are completely left out. Who trusts a report paid for by the government? Seriously? LOL

  2. Robert

    To say that climate change is not occurring because we had a cold winter is to completely misunderstand the implications of increasingly warm atmosphere and oceans. If you want to comment you can at least try to understand the issue.

  3. Kenneth

    Weather and climate are completely different things. We had a cold winter. The other side of the northern hemisphere was unusually warm. So warm that the Winter Olympic Games had to use man-made snow.

  4. Marc Blasband

    “The assumption that ozone and aerosols were about one-third more effective at warming the climate than well mixed greenhouse gases like carbon dioxide,”

    Where does this assumption come from?

  5. Graeme

    Kenneth – the “winter” Olympics were held at a resort where snow is very rare indeed. Palm trees line the streets.

  6. Good one Kris

    Good one, Kris! LOL. I suspect you live in the Eastern US, otherwise, you would have thought it was a very warm winter. Haha. http://www.ncdc.noaa.gov/sotc/service/global/map-percentile-mntp/201401.gif
    I know you were being sarcastic, but here is the “coldest” winter on record: http://www.ncdc.noaa.gov/sotc/service/global/lo-hem/201401.gif

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