© Zhangwei Ding (distributed via imaggeo.egu.eu)
In brief
News from the Arctic (2024.01)
© Terry Feuerborn on Flickr.com, CC BY-NC 2.0 DEE
Less sea ice could mean more trees in the Arctic
CREEPING TREELINES
A group of researchers from three American universities have found that the climate crisis may be prompting trees to expand north and at higher elevations. The team studied tree cover in Alaska’s Brooks Range, particularly white spruce, and found that the trees were gaining ground in the Arctic. They linked these changes to the loss of Arctic sea ice.
When sea ice retreats, large areas of open water are left behind, creating what is known as a warming “lake effect.” Typically associated with North America’s Great Lakes, this phenomenon speeds up evaporation and leads to heavier snowfall on nearby land. This layer of snow is making it easier for trees to survive in harsh Arctic conditions by insulating the ground and covering up and protecting small seedlings and saplings. It also keeps the ground warm enough for soil microbes to churn out the nutrients that trees need to grow. These insulating snow layers are also speeding up permafrost thaw, making it easier for trees to take hold in the soil.
The researchers used satellite imagery to track changes to the treeline in recent years. Over a four-year period, they also hiked some 2,400 kilometres to inspect trees and gather data. They concluded that distance to sea ice predicts tree growth and the probability of the forest advancing north.
Ice-free Arctic Ocean closer than predicted
SEA CHANGE
The Arctic Ocean could be seasonally ice-free up to 10 years earlier than scientists once thought.
According to a study published by researchers from the University of Colorado Boulder in the US, the region could have summer days with practically no sea ice within the next few years. As early as 2035, it could experience consistently ice-free conditions each year in September, the month when sea ice concentrations are typically at their minimum. By the end of the century, the ice-free season could last several months each year.
However, the exact year in which this will happen depends on how quickly the world reduces the amount of fossil fuels it burns.
The expected changes “would transform the Arctic into a completely different environment, from a white summer Arctic to a blue Arctic,” explains Alexandra Jahn, associate professor of atmospheric and oceanic sciences and a fellow at University of Colorado Boulder’s Institute of Arctic and Alpine Research. “So even if ice-free conditions are unavoidable, we still need to keep our emissions as low as possible to avoid prolonged ice-free conditions.”
The study defines “ice-free” as fewer than one million square kilometres of ice remaining because the region would be mostly water in that case. That amount represents less than 20 percent of what the Arctic’s seasonal minimum ice cover was in the 1980s.
© Tim Irvin / WWF-Canada
Climate crisis bringing big changes for Arctic rivers
NEW WATER PATTERNS
As the Arctic warms, thawing permafrost and intensifying storms could change how water moves into and through Arctic rivers, according to a new study.
The researchers used historical data, sophisticated computer models of Earth’s climate, and hydrology to reach their findings. They say the changes won’t affect just Arctic rivers, but also coastal regions, the Arctic Ocean and, potentially, the North Atlantic Ocean.
The region is already seeing more precipitation and thawing permafrost, leading to stronger river flows. Although most water going into Arctic rivers currently flows atop frozen permafrost in spring, the researchers predict that as the Arctic warms, more annual river flow will come from underground sources through subsurface pathways in the degrading permafrost.
When water flows through this soil, it picks up different chemicals and metals, such as nutrients and dissolved carbon, and can transport these to the ocean. As a result, coastal lagoons may become fresher, which would affect organisms throughout the food chain. In addition, warmer river water would melt coastal sea ice earlier in the season.
Deep-sea mining could worsen the climate crisis
HABITAT DESTRUCTION
A study published in the journal Frontiers in Marine Science reveals that deep-sea mining could increase the scale and speed of climate change by affecting seafloor creatures that store carbon.
The scientists from Norway and the UK surveyed seafloor animals, such as corals, sponges and snails, at 17 different sites on the floor of the Barents Sea. What they found was that these organisms store a far larger amount of carbon than was previously believed—and deep-sea mining could disrupt this.
“Previous estimates have underestimated how much carbon is being removed by marine life because they were based on data from troughs on the ocean floor,” explains Terri Souster, a researcher at The Arctic University of Norway and the study’s lead investigator. “We systematically assessed a wider range of seafloor sites and found that far more carbon is being removed in continental shelf waters.”
Seafloor creatures extract carbon from their food and the surrounding water to grow and build their skeletons or shells. When they die, much of that carbon stays locked away in their shells and skeletons, which sit in sediment on the sea floor. Deep-sea mining and trawling could reduce the oceans’ natural ability to remove carbon from the atmosphere by disturbing or destroying these habitats.
By WWF Global Arctic Programme
