The Arctic is on the front lines of climate change. It is a region that is warming faster than other parts of the globe, and the ice at the North Pole has become thinner and less extensive and with each passing decade. The Arctic Ocean also functions as a carbon sink; it can absorb about 180 million tons of carbon every year.
However, as the climate changes, conditions in the Arctic are being upended. Recent research has shown that as the frozen ground in the planet's North, permafrost begins to thaw, runoff that carries high levels of carbon is moving through the Mackenzie River in Canada, portions of the Arctic Ocean are now releasing more carbon than they absorb. The findings have been reported in Geophysical Research Letters.
The southeastern Beaufort Sea absorbs sediment and dissolved carbon that collects in rivers that run through the Northwest Territories of Canada. Some of that carbon is released into the atmosphere though natural processes.
In this study, the researchers aimed to learn more about what is happening to the carbon there using complex models that integrated over two decades worth of data collected by instruments on land and in the sea. The discharge of water and elements was modeled from 2000 to 2019.
This work showed that outgassing, the movement of carbon from water into the atmosphere, is intensifying so much that instead of acting as a carbon sink, the area now releases about 0.13 million metric tons of carbon dioxide per year into the atmosphere, about as much as 28,000 gas-powered cars. There was some seasonal variation due to changes in river flow.
Researchers have also started to notice a striking phenomenon in Arctic rivers: they are turning orange. Near the Brooks mountain range in the Yukon Territory in Canada, at least 75 streams and rivers in the area have turned a bright orange color in the past five to ten years. Scientists are still trying to figure out what is causing this disturbing change, but a leading hypothesis suggests that it is due to permafrost that is releasing oxidizing iron and sulfuric acid into the rivers. The pH of those waters is also changing dramatically and becoming highly acidic.
Scientists are also concerned that toxic metals may be seeping into the water as the permafrost continues to thaw, which could pose serious threats to wildlife that relies on the rivers for sustenance or survival.
An article in Scientific American describing these events has highlighted the dramatic changes in the Salmon River. This waterway was once so pristine that a 1980 conservation act described it as “water of exceptional clarity.” Now, however, the river is turning orange because of so many oxidized iron minerals.
While scientists will certainly continue to investigate the exact mechanisms that are causing the rivers to turn color, it is yet more evidence that urgent action is immediately needed to reduce the flow of carbon dioxide and other greenhouse gases like methane into the atmosphere.
Sources: NASA, Geophysical Research Letters
