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Scientists suggest that beaver ponds could worsen the effects of warming in the Arctic.
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Scientists suggest that beaver ponds could worsen the effects of warming in the Arctic.

Prior to this, the river in western Alaska had a vastly different appearance. In aerial photographs taken in the 1980s, it flowed smoothly through the tundra, resembling a thin thread. However, in more recent satellite images, it is now visible as a series of dark patches, with multiple large ponds separated by several meters.

The Arctic is currently undergoing a transformation due to large-scale landscape manipulation. However, this is not a human effort to alter the environment. Rather, it is the ongoing work of the North American beaver, with no indication of slowing down.

If the waddling rodents had not been making small advances, researchers would not have been able to detect them. However, the animals are now entering new regions, moving northward. The exact number of animals is uncertain, but the ponds they construct are difficult to overlook. In just the Alaskan Arctic tundra, the number of beaver ponds on streams has increased to at least 12,000 in the last two decades. Additionally, more lodges can be found along lakes and river banks.

Comparison of an aerial image of the Arctic tundra in Alaska from 1980 and satellite image from 2019

An ecologist from the University of Alaska, Fairbanks named Ken Tape is studying the increase of beavers in the northern region. He believes that this phenomenon is occurring on a large scale and his ongoing research suggests that the entire north slope of Alaska will be inhabited by beavers by the year 2100.

The increase in the number of beavers, which can reach a weight of up to 45kg, is a result of a decline in trapping and the transformation of a once inhospitable landscape. Due to global warming, the Arctic tundra has become more densely covered with shrubs, resulting in a shorter and milder winter season with increased water flow during the coldest months. As a result, beavers now use surrounding shrubs to build their dams and create deep ponds for their lodges instead of cutting down trees.

The recent additions create significant disturbance. In certain areas, the waterways serve as the main routes through the terrain, and the dams act as effective barriers. As these constructions increase in number, more land is submerged and there may be a decrease in clean water available for downstream consumption. However, there are also other, less noticeable impacts. The animals play a role in a cycle of cause and effect: changes in climate allow for the presence of beavers, whose ponds contribute to further warming, which then attracts even more beaver colonies.

The field of physics predicted that this event would occur. Beaver ponds are recently-formed bodies of water that cover exposed frozen ground. Due to the relatively warm temperature of the water, it causes the solid ground to thaw and release methane, a powerful greenhouse gas.

Scientists have gathered proof that this phenomenon is occurring. Using advanced satellite images, Tape and his team identified beaver ponds in the lower Noatak River region of north-western Alaska. They then studied infrared images taken by Nasa aircrafts flying over the area. Combining the two data sets revealed a noticeable connection between beaver ponds and areas with high levels of methane, which spread out for several meters around the ponds.

“The alteration of these waterways is a beneficial loop that is expediting the impacts of global warming, and that is worrisome,” states Tape. “They are hastening it at each of these junctures.”

Next year, the researchers will conduct ground measurements in order to better understand the methane levels. The Nasa images only capture a single moment in time, so more data is needed to determine how methane emissions change over time in beaver ponds. The researchers are particularly interested in whether the methane release remains consistent or decreases after a period of ten or twenty years.

Scientists are monitoring regions beyond Alaska as well, particularly in northern Canada where beavers are also migrating. The formation of ponds over permafrost will have a comparable impact. According to Tape, the extent of this issue in terms of geographical area and population is significant.

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Helen Wheeler, an associate professor at Anglia Ruskin University, collaborates with communities in the Gwich’in settlement area of northern Canada. In this region, the number of beavers seems to be increasing at a slower rate compared to Alaska, although surveys conducted using boats and drones still indicate a doubling since the 1960s. According to Wheeler, “While we have observed an increase in beavers, it is not as drastic as the exponential growth seen in certain parts of Alaska. The fluctuations from year to year likely reflect the harshness of the environment.”

The beavers have a positive impact as well. The small habitats they create can increase the diversity of the area. In addition, some groups may see the beavers as a potential food and clothing resource.

However, there are still concerns among many people. Although not all beavers construct dams, those that do can impact the quality of water and the movement of fish, as well as create barriers and hinder access to certain areas by causing floods and obstructing routes. Even without the added concern of methane emissions, both researchers and indigenous communities are questioning whether any actions should be taken.

In February, the topic will be open for debate among researchers, indigenous communities, and land managers who are part of the Arctic Beaver Observation Network. They will convene for their yearly gathering in Fairbanks, Alaska. This event will bring together specialists who oversee beavers in different areas to consider various solutions.

Tape suggests, “In the event of a problem, what actions can we take? I am without solutions.” He adds, “One option is to offer a reward and eliminate them, but once you cease, it will only be a matter of three to five years before you are faced with the same predicament. Additionally, it is practically infeasible to carry out such a task.”

According to Tape, people still consume them, although not as much as before. Personally, I have never tried it, but I believe that will soon change. I’ve heard it’s quite delicious.

Source: theguardian.com