Deniers delight — a negative climate feedback!

Occasionally, deniers commenters say I focus too much on the inordinate number of positive or amplifying feedbacks, whereby an initial warming causes changes that lead to more warming:

But just to show how balanced this blog is, I’m happy to report that researchers have found a (temporary) negative feedback that could slow some of the impacts of global warming:

The Arctic may get some temporary relief from global warming if the annual North American wildfire season intensifies….

Smoke transported to the Arctic from northern forest fires may cool the surface for several weeks to months at a time, according to the most detailed analysis yet of how smoke influences the Arctic climate relative to the amount of snow and ice cover.

Here is the full study, “Radiative impact of boreal smoke in the Arctic” (subs. req’d). This qualifies as a negative feedback because global warming has been predicted to lead to more wildfires (see “Global warming and the California wildfires” and “California wildfires update“). Here is “NOAA satellite image, June 30, 2004, showing wildfire smoke blanketing Alaska”:


“Smoke in the atmosphere temporarily reduces the amount of solar radiation reaching the surface. This transitory effect could partly offset some of the warming caused by the buildup of greenhouse gases and other pollutants,” said Robert Stone, an atmospheric scientist with the university and NOAA Cooperative Institute for Research in Environmental Sciences (CIRES) and lead author of the study, which recently appeared in the Journal of Geophysical Research.

How much solar energy is prevented from reaching the surface depends on the smoke’s opacity, the elevation of the sun above the horizon, and the brightness of the surface, according to the study.

So all you delayers out there who have been saying for years that the negative feedbacks overwhelm the amplifying feedbacks … well, you’ll still find no support for that Pollyannish view in the scientific literature. Even if the entire West burns to a cinder thanks to climate-driven wildfires, the Arctic is going ice free several decades ahead of what the models had predicted. And then it appears the really scary feedbacks will kick in (see “Tundra 4: Permafrost loss linked to Arctic sea ice loss“).

The time to act is still yesterday.


7 Responses to Deniers delight — a negative climate feedback!

  1. Adrian says:

    “Weeks to months”, huh? Is that enough time for all of the carbon emitted by the fires to disappear or does the smoke just give us a temporary lull before continuing faster than ever?

    I had read about how much additional carbon was being released due to Pine Beetles and other pests killing off huge swaths of forest in British Columbia and comparing it to industry and transport emissions. I’ve gotten used to thinking about human activity first, but these secondary effects can be just as large and often go unconsidered.

  2. Tom G says:

    The fires release CO2.
    The fires also leave blackened earth which will draw more heat. The smoke will shield the dark earth, but the smoke will not last forever. Even if the fires burn until the winter snows puts them out; the dark earth will be there next spring.
    The smoke will drop soot over a very wide area including Arctic ice. Of course soot is black, draws heat and will increase the rate of melt unless it is quickly covered with snow.
    I consider this smoke a positive feedback disguised as a negative.
    Sorta like pushing in the clutch on a stick-shift vehicle.
    There’s an interruption of power, but next up is a higher gear…

  3. jorleh says:

    As you pointed, the deniers are blind. The facts are there to see and taste, and these criminals continue business as usual. Why? Because they are evil.

  4. RhapsodyInGlue says:

    I believe this is yet another case of the dangers of reporting individual scientific papers in mainstream media. Papers are often very narrowly focused. This paper for instance is focused on the aerosol effects of fires. Right in it is a disclaimer that it doesn’t look at the albedo change effects from the soot.

    I doubt any of the scientists involved would say that it implies fires are a negative feedback, merely that while briefly aerosolized in the atmosphere the particles have a negative feedback effect.

    I find it very ironic that our citizenry ranks horribly low when it comes to math and science education, and yet everyone seems to think they know enough to debate the implications of every new scientific paper. Most Americans have such poor grasp of what science is about that merely thinking about it creates a reasonable doubt in the their minds… and a tendency to inaction.

  5. Joe says:

    Tom, Rhapsody — I had hoped my irony was more obvious.

  6. RhapsodyInGlue says:

    Rest assured, your irony was. The coverage on say PlanetGreen TV, however, presented this study as if it actually meant fires would help mitigate GHGs.

    I believe individual studies are misused by both sides of the debate. Caveats, limitations and nuances are often left out of coverage and sadly, most people are ill equipped to make an informed decision about the prudent interpretation of scientific results.

    The business as usual crowd has done a very good job of convincing the public that it’s valid to demand that science be debated as part of the political discourse. That is a flawed notion.

  7. was being released due to Pine Beetles and other pests killing off huge swaths of forest in British Columbia and comparing it to industry and transport emissions