Study: Black Carbon From Burning Rainforests Beginning To Speed Up Andean Glacial Melt

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Smoke plumes billow from Amazon forest fires and travel with the wind, carrying aerosols such as black carbon to settle upon the surfaces of mountain glaciers, darkening snow. As a result, the snow’s albedo — the amount of light and radiation reflected from the surface — is reduced as absorption is increases. With less sunlight reflected, the glacial energy balance is disrupted and the glacier melts more rapidly.

“What we found in our study was that for the tropical Andean glaciers, the main source of black carbon is the Amazon biomass burning. And that the black carbon content in snow due to Amazon fires is sufficient to cause melting,” study lead author Dr. Newton de Magalhães Neto of Brazil’s Rio de Janeiro State University, told Mongabay. The phenomenum may be relatively new, as the Amazon rainforest historically was too wet to burn significantly; climate change coupled with deforestation has caused it to grow increasingly dryer over recent years.

The research team used data from past fire events, precipitation, glacial melting and the movement of smoke plumes from the southwestern Amazon to model effects on glacial melting, specifically for the Bolivian Zongo Glacier. The research focused on black carbon deposition in 2007 and 2010, years when fires surpassed the devastating levels seen in 2019. According to the researchers’ model, both black carbon and dust in low concentrations (10 parts per million) on the surface of the snow can increase annual melting on the glacier by 3-4% separately, or by 6-8% in combination. Higher levels of dust (100ppm) can increase annual glacial melting by 12-14% when combined with black carbon.

“For us that was not a big surprise. We already knew that in Greenland, surface melting occurs not only due to greenhouse gases warming, but also due to surface deposition of black carbon,” said de Magalhães Neto. “Greenland receives large amounts of black carbon of fossil fuel origin due to North American and European industrialization, boreal forest burning from Canada, and from coal use in Russia, and black carbon plays a key role in the surface melting process.”

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https://news.mongabay.com/2020/01/what-starts-in-the-amazon-doesnt-stay-there-fires-melting-andes-glaciers/