Arctic warming up twice as fast as the rest of the earth. One of the results of this trend is the permprust thaw, a layer of soil that has remained frozen for thousands of years in some areas. Frozen soil and vegetation now holds more than twice the carbon found in the atmosphere.
Like permafrost across northern Alaska, Canada, Siberia and other high latitudes, bacteria in the soil consume organic materials, releasing carbon dioxide or methane, and even more powerful greenhouse gas, into the lakes and atmosphere.
But a warmer, wetter climate may also cause more carbon from the plants on the ground to move into the lakes. Increased carbon flow from plants and soils to Arctic lakes generates more greenhouse gas emissions than water bodies. And in a largely indistinguishable region with millions of lakes, it is still a mystery how much carbon moves from country to lake, and eventually into the atmosphere.
New research by the University of Washington and the US Geological Survey suggests that many lakes pose a small threat to global carbon levels, at least for now. In the arid, arid regions of thousands of lakes – a landscape that accounts for about a quarter of the Arctic – many lakes act like independent units, and do not release much carbon dioxide.
"We found that not all high-width lakes are large chimneys of carbon into the atmosphere, and that the lakes in the area are not actively processed permafrost or carbon plant from the ground," said lead author Matthew Bogard, a postdoctoral researcher at the UW School of Environmental and Forest Sciences. "Documentation of the heterogeneous nature of northern lakes, as we have done here, will better define the role of Arctic lakes in the global carbon cycle."
The study will be published online February 11 in the journal Nature Geology.
The researchers visited 20 lakes several times during the year in the Yukon area of northeast Alaska: a vast, dry landscape dotted with thousands of lakes home to the Yukon River, the last largest river of North America. Their goal was to track the flow of carbon through the food network and test the chemistry of the water in each lake in search of carbon markers from permafrost over an area previously unexplored in this way. Almost all of the studies related to the existence of a handful of individual areas in the Arctic that do not necessarily represent the characteristics of lakes in the region, the researchers said.
"The problem we have overcome in this study is to get to very difficult logistics places to get a better picture of what is happening across the North Pole, which actually has millions of lakes," said senior author David Butman, professor of UW School of Environmental and Forest Sciences. "These findings show the need to better understand the diversity of ecosystems in this region."
During each of the field trips, the research team flies by floatplane from Fairbanks, Alaska, to a remote location of Yukon National Wildlife Refuge Apartments, a bustling area every summer with migratory ducks and other water birds. Their accommodations were modest: an old hunting lodge that the Brazilian fish and animal government had given her a safe place to sleep, cook, charge and filter out water after days on the ground. Black bears and deer are common in this area, evidenced by large thorns on the cell doors and windows to keep the animals away.
Every day the researchers flew from lake to lake, collecting water samples while squatting on the jet boats and releasing rain to the water to measure temperature, dissolved oxygen and other lake properties. On a good day, two researchers and a pilot could hit eight different lakes, sometimes forced to leave a person behind for part of the day if the lakes were too shallow to take off with a fully weighted airplane.
In their analysis, the researchers found that almost every lake they tested did not show any sign of ancient carbon from permafrost, and less production of carbon dioxide than expected.
Lakes emit carbon dioxide when it enters from external sources in the landscape, such as rivers and groundwater. Also, bacteria and animals produce it while digesting their food, and carbon dioxide can build up if they produce it faster than algae plants can suck it during photosynthesis.
But here, the research team saw evidence that many of the lakes were more balanced in the production and production of carbon dioxide than lakes in other regions. As a result, the lakes were a smaller source of carbon dioxide into the atmosphere than in other parts of the world.
"The implication is that not all lakes are hot spots to release carbon from land," said Butman. "But we still do not know how these landscapes will change in warmer climates, because this is the first time they've been questioned."
As the climate warms up, large wildfires are expected to sweep the Yukon apartments, potentially providing a huge load of carbon and lake land in this landscape that could trigger more carbon dioxide emissions. The current and current research work of the research team will assist in benchmarking what is happening now to better understand future changes.