A great article was posted on the Guardian website yesterday, written by Dr John Abraham, in which he highlights research that shows that if it weren't for aerosols, Arctic sea ice loss would've been even greater:
Pollution is slowing the melting
of Arctic sea ice, for now
Human carbon pollution is melting the Arctic,
but aerosol pollution is slowing it down
NASA satellite photo of the minimum extent of Arctic sea ice in 2005 that occurred on September 21, when the sea ice extent dropped to 2,05 million square miles (53 094 969 million square kilometers). Photograph: HO/AFP/Getty Images
The Arctic is one of the “canaries in the coal mine” for climate change. Long ago, scientists predicted it would warm quicker than other parts of the planet, and they were right. Currently, the Arctic is among the fastest-warming places on the planet. Part of the reason is that as the Arctic warms, ice melts and ocean water is uncovered. The ocean is darker than ice so it in turn absorbs more sunlight and increases its warming. This is a feedback loop.
Another reason is that the Arctic doesn’t get that much sunlight so increased energy from the atmosphere has a bigger influence there than it would have elsewhere.
Scientists have looked to the Arctic for clues and hints of human climate change over the past decades. The fact that the Arctic is warming has led to a 70% reduction in the volume of summer sea ice – an enormous loss of ice.
Decline in September Arctic ice extent (not volume). Illustration: NASA
A recent paper just published in the Journal of Climate by the American Meteorological Society takes an in-depth look at how fast the Arctic ice is melting and why. According to the paper, the authors completed a detection and attribution study of Arctic sea ice decline from 1953 to 2012. That is 60 years of data that tell the picture of climate change. The “detection” part of this study was about detecting what long-term trends are apparent over these six decades. The “attribution” part of the study is figuring out what is the cause of the trends.
In terms of attribution, the authors looked for “fingerprints” of human activity. Humans emit greenhouse gases that trap heat. We know that and we have known that for a long time. Greenhouse gases make the Arctic warmer. But, other things are happening too. There are natural changes to the Arctic. There are also other human pollutants that affect the ice. For instance, humans emit small particles called “aerosols” that can get into the atmosphere and block sunlight. So, these human aerosol emissions can actually cause cooling.
The authors concluded that the combined cooling effect from human aerosols was detected in all three datasets of ice. That means, it didn’t matter whose measurements you used – the effect of aerosol cooling was present.
So how much of an effect do aerosols have? It turns out 23% of the warming caused by greenhouse gases was offset by the cooling from aerosols. Unfortunately, this isn’t good news. It means that if/when humans reduce our aerosol pollution, the warming in the Arctic and the ice loss there will be worse.
Read the rest of the article here (I get quoted at the end of it!).