New Research: Volcanoes May be Slowing Warming

March 4, 2013


Well, not much, really. Certainly not enough to keep sea ice melt, ice sheet loss, glacier melt, and extreme weather events from accelerating beyond projections.  Useful input to the discussion in any case. Implications for geo-engineers?

University of Colorado:

A team led by the University of Colorado Boulder looking for clues about why Earth did not warm as much as scientists expected between 2000 and 2010 now thinks the culprits are hiding in plain sight — dozens of volcanoes spewing sulfur dioxide.

The study results essentially exonerate Asia, including India and China, two countries that are estimated to have increased their industrial sulfur dioxide emissions by about 60 percent from 2000 to 2010 through coal burning, said lead study author Ryan Neely, who led the research as part of his CU-Boulder doctoral thesis. Small amounts of sulfur dioxide emissions from Earth’s surface eventually rise 12 to 20 miles into the stratospheric aerosol layer of the atmosphere, where chemical reactions create sulfuric acid and water particles that reflect sunlight back to space, cooling the planet.

Neely said previous observations suggest that increases in stratospheric aerosols since 2000 have counterbalanced as much as 25 percent of the warming scientists blame on human greenhouse gas emissions. “This new study indicates it is emissions from small to moderate volcanoes that have been slowing the warming of the planet,” said Neely, a researcher at the Cooperative Institute for Research in Environmental Sciences, a joint venture of CU-Boulder and the National Oceanic and Atmospheric Administration.

The new study relies on long-term measurements of changes in the stratospheric aerosol layer’s “optical depth,” which is a measure of transparency, said Neely.  Since 2000, the optical depth in the stratospheric aerosol layer has increased by about 4 to 7 percent, meaning it is slightly more opaque now than in previous years.

“The biggest implication here is that scientists need to pay more attention to small and moderate volcanic eruptions when trying to understand changes in Earth’s climate,” said Toon of CU-Boulder’s Department of Atmospheric and Oceanic Sciences.  “But overall these eruptions are not going to counter the greenhouse effect. Emissions of volcanic gases go up and down, helping to cool or heat the planet, while greenhouse gas emissions from human activity just continue to go up.”

6 Responses to “New Research: Volcanoes May be Slowing Warming”

  1. I was thinking reflections like that would be seen as increase in some wavelength measured from a satellite.

  2. rayduray Says:

    When I look at images of the planet from space, one photo always jumps out at me. It’s the brown clouds over China and India.

    I understand the point of the Neel study. But I do have to wonder at humanity’s willingness to foul its own nest.

    For those with an interest in volcanoes, I recommend the Eruptions blog:

  3. […] Well, not much, really. Certainly not enough to keep sea ice melt, ice sheet loss, glacier melt, and extreme weather events from accelerating beyond projections. Useful input to the discussion in …  […]

  4. So, as we know, the IPCC graphs were off by a fraction of a degree – specifically, they predicted more warming.

    …Could this be the reason why? Someone better crunch those numbers!

  5. joffan7 Says:

    Of course the volcanoes won’t increase their activity without limit, so eventually the climate will jump back to the carbon-dioxide driven trajectory.

    And volcanoes don’t have an influence on ocean acidification, so that continues unabated.

  6. […] still figuring things out (like for example that the models predicted too much warming because we underestimated the cooling of volcanic eruptions), but the evidence remains incredibly strong that CO2 is, next to the sun, the main driver of […]

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