One side effect of a warmer Arctic, it will be cleaner due to black carbon scavenging

No polar bears and Arctic foxes  aren’t scavenging carbon, but more moisture during summer months will.

Arctic air may become cleaner as temperatures rise

The air in the Arctic is cleaner during summer than during winter. Previous studies have shown that for light-scattering pollutants, this seasonal cycle is due mainly to summer precipitation removing pollutants from the air during atmospheric transport from midlatitude industrial and agricultural sources.

With new measurements from Barrow, Alaska, and Alert, Nunavut, Canada, Garrett et al. extended previous research to show that light-absorbing aerosols such as black carbon are also efficiently removed by seasonal precipitation.

Precipitation removes these particles from the air most efficiently at high humidities and relatively warm temperatures, suggesting that as the Arctic gets warmer and wetter in the future, the air and snow might also become cleaner. If Arctic aerosols have a net warming effect, as is believed to be the case, precipitation removing these particles from the air would represent a negative climate feedback, mitigating anticipated Arctic warming.

Source: Geophysical Research Letters, doi:10.1029/2011GL048221, 2011 http://dx.doi.org/10.1029/2011GL048221

Title: The role of scavenging in the seasonal transport of black carbon and sulfate to the Arctic

Authors: Timothy J. Garrett: Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah, USA;

Sara Brattstrom: Meteorologiska Institutionen, Stockholms Universitet, Stockholm, Sweden;

Sangeeta Sharma and Douglas E. J. Worthy: Environment Canada, Toronto, Ontario, Canada;

Paul Novelli: GMD, ESRL, Boulder, Colorado, USA.

Abstract:

In a prior study, a decade-long dataset of ground-based aerosol and carbon monoxide measurements from Barrow, Alaska (71°N, 157°W) was used to show that surface air in the Arctic is clean during the summer, less due to inhibited transport of pollutants from mid-latitudes, and more because of efficient wet scavenging at temperatures near freezing. Here, the analysis is extended to light-absorbing aerosols, such as black carbon, and to measurements from Alert, Canada (82°N, 62°W). The data imply that both light scattering and light absorbing aerosols have similar seasonal cycles, independent of location, and they are controlled nearly equally by wet scavenging. Removal is particularly efficient at high relative humidities and warm temperatures, which suggests that a future warmer and wetter Arctic may also be cleaner. Assuming aerosol pollutants generally have a warming effect in the Arctic, such an increase in wet scavenging would represent a negative Arctic climate feedback.

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22 thoughts on “One side effect of a warmer Arctic, it will be cleaner due to black carbon scavenging

  1. So, um… another automated self-regulating system?

    The theory would then be thus: Aerosol pollutants increase warmth. Warmth removes aerosol pollutants. With said aerosol pollutants gone, warmth decreases. Decreased warmth means more aerosol pollutants. Repeat.

    As usual, I’m left wondering: where is the panic? Where is the emergency? Where is the catastrophe?

  2. So black soot falls on ice, ice then melts dropping black soot to ocean floor, bare water now exposed to arctic nights, water freezes clean and hard, rinse and repeat. Yep sounds like something to panic about. /sarc

  3. Hey, measurements! And not a single mention of models! Furthermore, it’s not worse than we thought! Incredible.

  4. We all concentrate on the ice thickness at the minimum ice extent in the summer but it could be that ice thickness varies at the maximum extent of the ice after winter.When we have faster growth of ice as we had in 2008 then the ice does not reach such a low minimum ,if we see a repeat of 2008 this winter then we might see an increase in arctic ice minimum next summer.

  5. So, soot on the ice increases evaporation/sublimation rates. The water vapor carries energy up into the atmosphere, where it mixes with airborn aerosols to form clouds. Energy is released when the water vapor condenses, half of which is radiated out to space. The condensed ice/snow then falls to the ground to cover the soot on the ground and remove soot from the air. Seems strongly negative to me, and supports willis’s cloud thermostat theory in the arctic.

    this ties into a study I linked to in tips and notes as well.

  6. While nice to see this data in a peer reviewed article, it’s one of those “duh” points of interest that anyone who looks toward the horizon after a long dry spell followed by a significant rain event can see with their own two eyes. Here in NW Louisiana we’ve been experiencing this two year drought and the air particulates have been very high. We’ve received a few light showers recently that have, in the short term, improved air quality. They have been insignificant in terms of easing the drought by no more than greening up grass and reducing the wildfire threat in the areas which recieved this moisture.

  7. This post proves that this isn’t “a lousy denial site” like everyone claims. We accept that global warming is happening… just not when people are all “doom and gloom” about it.

  8. This also ties into an hypothesis I came about myself early on in the whole AGW meme. I had seen a piece about the Arctic Ocean becoming ice free and another piece about some heavy lake effect snow off the Great Lakes. Well, when you put two and two tegether, does this not show that there is a very strong feedback mechanism? I observed the very process I supposed would happen two winters ago here in NW La. The ground was warm and saturated and a powerful cold front came over the area. I went out at night with a strong LED flashlight with a tight hotspot (beam). While the sky was clear, it was snowing small pin flakes via evaporation-condensation at the surface. Any aerial surface that had already frozen was showing a light accumulation of this frozen precipitation.

    Now put this into a grand scale overland near an unfrozen Arctic ocean once the air temps drop below freezing in September and you set the stage for tremendous amounts of frozen precipitation to build the supposedly melting ice sheets.

    I only see negative feedback to an open Arctic Ocean and don’t see much wrong with an hypothesis that warmer open ocean in the Arctic is followed by quickly growing ice sheets overland.

  9. Katherine says:
    September 22, 2011 at 9:21 am

    Absolutely – now we just need the rest of climate science to try the same thing!

  10. They are looking forward to the next funding cycle and getting their dibs in.
    How can they assume a warmer future, particularly for a region that gets almost no solar input during the vast majority of the year?

  11. ……as the Arctic gets warmer and wetter in the future,

    This is the clever art of the unsupported assumption. The DMI temperatures don’t appear to show ‘warmer’ being what is happening.

  12. Is the reason for lower soot in the arctic summer that less is being produced in China to heat homes and buildings?

    They also state “Precipitation removes these particles from the air most efficiently at high humidities and relatively warm temperatures…”. Do their new measurements from Barrow, Alaska, and Alert, Nunavut, Canada, Garrett et al. show high humidities and relatively warm trmperatures? How warm is relatively warm? I see more questions thatn answers in this article.

  13. Well, that’s all very fine if the Arctic becomes warmer and wetter. But what if it becomes colder and drier? Will the soot then force it to get warmer and wetter despite itself?

    The bind moggles.

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