What Dust May Have To Do With Earth’s Rapidly Warming Poles

by | 1.9.2013 at 11:31am | 1 Comment
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A 2005 dust storm over the Gulf of Alaska originated with glacial sediments left by retreating glaciers. (NASA)

As earth’s climate warms, scientists have tried to understand why the poles are heating up two to three times faster than the rest of the planet. Airborne dust, it turns out, may play a key role.

In a new study in Nature Climate Change, researchers show that at the peak of the last ice age, some 21,000 years ago, the poles were 10 times dustier than today, while areas closer to the equator had twice as much dust. During this time of extreme cold, New York City was under two miles of ice and up to 12 degrees F colder than today while Greenland was about 45 degrees F colder. The study’s authors suggest that higher atmospheric dust concentrations at the poles during the last ice age helped to cool earth’s surface and prevent snow and sea ice from melting during summer.

Lambert has traveled to Antarctica to extract ice cores that contain a record of dust and climate fluctuations in the past. (Patrik Kaufmann)

Strong winds sweep dust containing tiny mineral particles from the ground and into the air, across continents and oceans. In the atmosphere, dust influences climate by reflecting and absorbing sunlight, influencing cloud formation and seeding the oceans with nutrients that allow microscopic plants to grow. In today’s world, the poles have relatively little dust.  Scientists are unsure why the polar regions were so much dustier during glacial periods than interglacials like today, but stronger winds and changes in atmospheric circulation and precipitation patterns probably played a major role.

Climate modelers have struggled to reproduce the extreme cooling that took place at the poles compared to the rest of the planet during the last ice age, casting doubt on the accuracy of their forecasts. “This failure makes it hard for climate models to accurately predict how much warmer the poles will get in the future,” said the study’s lead author, Fabrice Lambert, a climate scientist at Korea Institute of Ocean Science and Technology. “We find that the models underestimate glacial polar dust concentrations as well.”

Today, temperatures are rising rapidly as humans put large amounts of heat trapping gases such as carbon dioxide and methane into the air. Could dust help to cool things off? Some scientists think that the future could be dustier as climate change, the razing of forests and over pumping of ground water create more deserts. In Asia and Africa, a doubling of dust emissions in some regions over pre-industrial levels has already occurred. At the same time, increases in soot and other industrial atmospheric particles that warm the climate could more than offset any dust-related cooling.

“Humans are changing the planet in so many ways that it’s hard to say how it all will influence climate in the end,” said study coauthor Gisela Winckler, a geochemist at Lamont-Doherty. “We know that dust and other atmospheric particles are an important piece of the puzzle, and that more observations from the past can help us better understand what will happen in the future.”

More

Arctic Dust Storms: Really? Washington Post, Nov. 24, 2010

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One Response to “What Dust May Have To Do With Earth’s Rapidly Warming Poles”

  1. Rick Poynter says:

    I find the statement that atmospheric solids such as soot from industrial process can add to global warming interesting. I’d be intrigued to learn whether the dust in the polar atmosphere contributed to cooling around 21,000 years ago, because of reflection or because of the influence of atmospheric solids on the specific heat of the atmosphere? My guess is that higher atmospheric solids will inevitably increase the specific heat of the atmosphere, so that where the ambient temperature remains below 0 deg. C, higher solids would support an increase in the accumulation of ice, but above 0 deg C, the reverse would apply, compared with what would apply with lower or no atmospheric solids. All the popular talk about human induced climate change since the beginning of the industrial age has tended to focus on GHG, and CO2 in particular, but it wouldn’t surprise me to find that atmospheric solids ultimately prove to be of greater significance than say increased CO2 levels, essentially because of the effect of solids on the specific heat of the atmosphere. The much greater volume of industrial activity (and land mass) in the northern hemisphere, would seem to support this basefd on what appears to be happening at the poles at present, and the simple comparison of what it feels like, being anywhere in Europe in summer with a reported day time air temperature of 30 deg C, compared with a reported 30 degree C summer day anywhere in New Zealand, is like chalk and cheese. 30 Deg C in Europe is comfortable. 30 deg C in NZ you’re getting fried!

    Some atmospheric dust will be inherently reflective, but not all, and presumably even the reflective dust will increase the atmospheric heat sink potential during the hours of darkness?

    I have no idea how the concentration of atmospheric solids diminishes with altitude, nor with latitude, but I’d be very interested in some learned comment.

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