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Tundra 3: Forests and fires foster feedbacks

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"Tundra 3: Forests and fires foster feedbacks"

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Part 1 looked at why “The permafrost won’t be perma for long.” Part 2 looked at whether the potential destruction of the tundra represents “The point of no return” for the climate, necessitating that we keep atmospheric concentrations of carbon dioxide below 450 ppm or else risk going to 800 ppm to 1000 ppm. Here I examine two local amplifying feedbacks that further threaten the permafrost — forests and fires.

Reduced snow cover and albedo (reflectivity) in the summertime Arctic landscape, caused by global warming, has added local atmospheric heating “similar in magnitude to the regional heating expected over multiple decades from a doubling of atmospheric CO2” (Science, subs. req’d). That same Science study warns “Continuation of current trends in shrub and tree expansion could further amplify this atmospheric heating 2-7 times.”

tundra-trees.jpg

The point is that if you convert a white landscape to a boreal forest, the surface suddenly starts collecting a lot more solar energy. That trend is occurring now, as seen in these two photos from a recent ScienceNews article, “Boreal forests shift north.”

“Upper photo taken in 1962 shows tundra-dominated mountain slope in Siberian Urals. A 2004 photo of the same site, below, shows conifers were setting up dense stand of forest.”

Now, another major study warns that the warming-driven northward march of vegetation poses yet another threat to the tundra.

The study, “Frequent Fires in Ancient Shrub Tundra: Implications of Paleorecords for Arctic Environmental Change,” finds:

greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21st century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as on land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere.

tundra-fire-2.jpg

The concern is not so much the direct emissions from burning tundra. As the article concludes:

… studies of modern tundra fires suggest the possibility for both short- and long-term impacts from increased summer soil temperatures and moisture levels from altered surface albedo and roughness, and the release soil carbon through increased permafrost thaw depths and the consumption of the organic layer.

Click on the image above to see just how much the fire changes the albedo (reflectivity) of the tundra landscape.

We must get serious about educing greenhouse gas emissions now, since the consequences of hitting 1000 ppm are simply too dire to risk (see “Is 450 ppm (or less) politically possible? Part 0: The alternative is humanity’s self-destruction“).

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15 Responses to Tundra 3: Forests and fires foster feedbacks

  1. caerbannog says:

    In addition, bark-beetle infestations are devastating forests further south, releasing still more sequestered CO2.

    Folks should check out http://www.for.gov.bc.ca/hfp/mountain_pine_beetle/maps/magnitudeMap2007.pdf
    and http://www.for.gov.bc.ca/hre/bcmpb/cumulative/2008.htm to get an appreciation of the magnitude of the infestation in British Columbia.

    The region of the most severe beetle infestation (with most of the trees dead or dying) spans an area on the order of half the size of California!

  2. Nylo says:

    I”m troubled about your last paragraph. Do you mean that if we don’t get serious about reducing greenhouse emissions now, we are going to hit 1000 ppm? When?

    As for the two photos provided, do you really see a decrease of the Albedo in the later photo compared to the earlier one? I see a lot more snow. Also, in the second photo, I see more and bigger trees in the same area, but I don’t see the forested area changing. Wherever I see a tree in the second photo, I can also find trees in the first one. Just less and smaller. It’s normal. Plants grow up, and there’s a 40 years time difference. And plants growing up is a good thing for CO2 absorption.

  3. Arne Marco says:

    I would say we are already 100 ppm over where we should be. It is not a question of reducing, is actual a question of stopping. Because of the long time the CO2 stays in the atmosphere and the time it takes to get there even if we stopped all CO2 emissions today, it will still grow for a time, surely to pass 400 ppm. Every ppm we allow CO2 to rise will gives us more problems in a near or far future.

    The danger lay in the unknown runaway processes that might have started already in the Arctic or in the tundras …

  4. Nylo says:

    A forest fire will lower the Albedo of a tundra with trees for a couple of months, until it snows again. Then, for the following 20 years, a tundra without trees would have quite a reduced albedo, wouldn’t it?

  5. Nylo says:

    Arne, if we stop all CO2 emissions today, CO2 concentration in the atmosphere will not only stop increasing but start to reduce. It is by keeping CO2 emissions stable instead of increasing that the concentration would continue to increase too.

  6. Joe says:

    Nylo — the photo was obviously not taken during the snow-covered season. That is when the Trees would dramatically change the albedo.

    The forest fire will change the albedo the most during the non-snow-covered season. It is an interesting question as to whether reduction in trees during the winter would have a bigger impact than the darker surface during summer — presumably the darker surface is much larger in the area of trees.

    I see more trees, but I’m not sure you can see the forest for the trees….

  7. Reader says:

    Hey, did you guys hear that An Inconvenient Truth is going to be made into an Italian opera? Isn’t that exciting?

  8. charlie says:

    Joe — great series. You are much stronger when doing this explaining, or “the wedges” than when on the attack.

  9. exusian says:

    Nylo wrote: “Also, in the second photo, I see more and bigger trees in the same area, but I don’t see the forested area changing.”

    More and bigger trees in an area where trees are typically few and stunted is not a change?

    There’s a reason the tree line is called the tree line.

    And there is a reason the tree line is moving northward.

    Obviously those reasons have escaped Nylo’s comprehension.

  10. Robert says:

    Arne

    “The danger lay in the unknown runaway processes that might have started already in the Arctic or in the tundras …”

    Another danger we don’t talk about much is the runaway process of global industrialization. This now looks unstoppable.

  11. agog says:

    To this layman’s eye the maps showing the extent of mountain pine beetle infestation in British Columbia linked to above by Caerbannog are very ominous indeed.

    Are the climate ramifications of losing an expanse of forest of this size (and more in the future, presumably) quantifiable? Even if methane isn’t an issue at those latitudes, am I correct in assuming the loss of carbon sink effect combined with carbon emissions from the inevitable forest fires will be significant?

    Joe, do please write about this if you haven’t already. (Cracking blog, btw.)

  12. agog says:

    Sorry. Have just found your April 25 post. Bleh! Grim stuff.

  13. hapa says:

    i’ve been wondering for a couple weeks now what constitutes a green roof. i’m starting to think it’s a highly-insulated cool roof, to increase albedo, instead of plants or PV shingles.it occurs to me that if photovoltaic devices could be made translucent, they could be placed on a white backing and have the light pass through them roughly twice, allowing reflection and generation at once.

  14. hapa says:

    cat’s-eye power.

  15. Dano says:

    Bark beetles are also devastating Colorado in the US, and are moving into Wyoming. Other beetles are in the pondo forests in Arizona and California. The understanding at this time is the cause is multiple factors – a combination of drought, warm winter temps and fire suppression.

    The issue in BC (I backpacked in Cathedral Lakes two autumns ago and can attest to the devastation) and the US is multifold. In Colorado there will be less snowpack – and down on the Front Range, that likely will result in depopulation in a few decades, as the aquifers will be depleted and less runoff will mean the current human population (future growth notwithstanding) won’t have enough water to sustain it.

    Best,

    D