The study found that the greening of the Arctic occurred due to the “rapid increase in summer air temperatures over the past three decades.”
Researchers used Landsat data and additional calculations to estimate the peak greenness for a given year for each of the 50,000 sites that were selected across the Tundra. Between 1985 and 2016, about 38 per cent of the tundra sites across Alaska, Canada, and western Eurasia showed greening. 22 per cent of sites greened between 2000 and 2016, while 4 per cent browned.
The two images show the changing landscape in Arctic. (Source: Nasa)
The Arctic lost 3.74 million sq km of ice cover in 2020
Meanwhile, the Arctic sea ice cover shrank to the second-lowest extent in 2020 by 1.44 million square miles (3.74 million square km). The increase in the ice melt is being subjected to the Siberian heat wave that pushed the average temperature in the region to 8 to 10 degrees Celsius warmer than average.
“It was just really warm in the Arctic this year, and the melt seasons have been starting earlier and earlier. The earlier the melt season starts, the more ice you generally lose,” NASA
quoted Nathan Kurtz, a sea ice scientist at Goddard Space Flight Center in Greenbelt as saying. The lowest extent of ice cover shrinking on record was set in 2012.
The image on the right shows the ice cover loss, which can have detrimental impact on global system. (Nasa)
According to NASA, dramatic drops in sea ice extent in 2007 and 2012, along with generally declining summers, have led to fewer regions of thick, multi-year ice that has built up over multiple winters. A recent study showed that warmer water from the Atlantic ocean, which is typically deep below the colder Arctic waters, is creeping up closer to the bottom of the sea ice and warming it from below.
Global impacts of a warmer Arctic
With the pole losing its ice and the tundra getting greener the change can have a devastating impact on local ecosystems, regional and global weather patterns, and over 4 million human lives who call the frozen land, home.
Arctic sea ice acts as a huge white reflector at the top of the planet, bouncing some of the sun’s rays back into space, helping keep the Earth at an even temperature. As the melting heightens, there is less ice to reflect these rays, and more heat is absorbed by the ocean, magnifying the warming effect. The Arctic also helps circulate the world's ocean currents, moving cold and warm water around the globe. The change in the biome will affect this movement, triggering events on a global scale from irregular El-Nino occurrence to unannounced droughts.
Polar bear sow and cub walk on ice floe in norwegian arctic waters as the lose their habitat to climate change.
“The Arctic tundra is one of the coldest biomes on Earth, and it’s also one of the most rapidly warming,” said Logan Berner, a global change ecologist with Northern Arizona University in Flagstaff, who led the research. “This Arctic greening we see is really a bellwether of global climatic change – it’s a biome-scale response to rising air temperatures,” he added.
While active plants will absorb more carbon from the atmosphere, the warming temperatures could also be thawing permafrost, thereby releasing greenhouse gasses. “Whether it’s since 1985 or 2000, we see this greening of the Arctic evident in the Landsat record,” Berner said. “And we see this biome-scale greening at the same time and over the same period as we see really rapid increases in summer air temperatures.”
An Arctic Fox looks on as the surrounding turns green owing to climate change.
Hinting at global climate change, the study pointed, “It is possible that indirect drivers of vegetation change, such as permafrost thaw and nutrient release, are accumulating in response to warming of summer air temperatures, or that plants are limited by other environmental constraints.” While wildfire is another contributor to greening and browning in the Arctic the study indicates that their contribution is currently quite small at a pan-Arctic level due to infrequent occurrence.