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Chaos Full-tilt a have descended into the Arctic, a region that is now warming twice as fast as the rest of the planet. This summer, it was hot under an unprecedented heat and the forest fires have devastated up to now 2,4. million in Alaska, releasing massive amounts of carbon dioxide. It is so hot that thunderstorms, more common in the tropics, strike near the North Pole.
Add to this bizarre affair a strange, perhaps counter-intuitive, conclusion in the far north of Canada, right next to Greenland. Researchers have found that glacier-fed watersheds actually absorb a significant amount of carbon dioxide, unlike a typical carbon dioxide-emitting river. On average during the 2015 melt season, per square meter (to be clear, not in total) these glacial rivers consume twice as much CO2 like the Amazon rainforest. Ironically, melting glaciers under the weight of global warming can contribute to carbon sequestration, making these watersheds a previously unrecognized CO.2 sink.
If you were looking for a way out of our imminent climate catastrophe, however, that's not it. On the one hand, the sequestering powers of glacial meltwaters can not keep up with our uncontrollable emissions, or even other emissions induced by climate change from the Arctic, such as melting permafrost . And if we continue to melt the glaciers, we will also run out of meltwater. Nevertheless, the results are a key element in understanding the monumentally complex carbon cycle on this planet.
Glacial rivers are very different from rivers elsewhere in the world. A striking difference is that they are largely abiotic: algae and fish do not usually colonize them because they are too cold. So, instead of being filled with life, they are filled with sediment.
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"As these glaciers retreat or advance, as they do each year, they actually form a lot of very fine sediments that open wide open onto the landscape," says Kyra A. St. Pierre , biogeochemist at the University of British Columbia and lead author of a new article describing the results. Glacial meltwater picks up these sediments, making them rich in minerals. These rivers of meltwater then congregate in glacial lakes rich in minerals.
Jessica Serbu
The problem with carbon dioxide is that it flows freely on the surface of the water – the water can both absorb and release the gas. In a typical river, organisms consume organic matter and emit CO2or breathable, as humans do. Thus, the river becomes a net producer of carbon dioxide because it is saturated with so much CO2 that water simply can not dissolve CO2 from the air. The same goes for ponds and lakes around the world: they are emitters of greenhouse gases.
Glacial meltwater, on the other hand, does not have this organic respiration, so it can dissolve more CO2 from the air. Sediments that meltwater collects along the way consume the CO2 which is dissolved in the water. "Sediments mix in the water and mix with the carbon dioxide in the atmosphere, which changes the chemistry of the river as it travels downstream," says St. Pierre. When the sediment reacts with CO2Part of the material dissolves, so that the river becomes a sinuous carbon sink.
To an impressive degree, actually. During the relatively low melting season of 2016, rivers in this Arctic watershed consumed twice as much carbon per square meter per day as the Amazon rainforest. But the year before, which saw three times the melting of the ice, the rivers consumed on average twice as much as the Amazon. At one point, they captured 40 times more CO2 like the Amazon per square meter. But again, it's not in total. The Amazon rainforest stretches over 2 million square kilometers, an extent that vastly eclipses the size of this glacial watershed.
Yet, there emerges a carbon sink up here neglected. It would be extremely difficult to tell the world how much carbon melt is being captured, even before climate change begins to wreak havoc in Arctic systems. But the beauty of this work lies in the fact that it brings a certain understanding to complex phenomena. "The Arctic is moving much faster than even our best models predicted," says Rose Cory, a biogeochemist at the University of Michigan, who did not participate in this work. "And to be able to model or project what is happening, we need to have this process information."
Researchers need to better understand the impact of the rapid melting of glaciers on freshwater systems. And also how much CO2 these meltwaters can capture, allowing scientists to establish more robust carbon budgets or estimate the amount of carbon we can emit into the atmosphere if we want to achieve the objectives of the Paris Agreement. "I think this study is a very good example of the work needed," says Cory.
To be clear, this study did not find the geochemical savior of mankind in glacier meltwaters. These rivers and lakes aspire of CO2, Yes. "But at the same time, you also have these other changes in the high and low Arctic that will dominate the CO.2 relax from the warming, "says Cory. "For example, thawing permafrost will release carbon dioxide, which can not be offset by what happens in these glacial lakes."
Nevertheless, a carbon sink is a carbon sink and a better understanding of these complex processes makes it possible to better target a chaotic carbon cycle.
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