It’s not just polar bears that are suffering as Arctic sea ice retreats.
Tens of thousands of reindeer in Arctic Russia starved to death in 2006 and 2013 because of unusual weather linked to global warming. The same conditions in the first half of November led to both famines, which killed 20,000 deer in 2006 and 61,000 in 2013.
Sea ice retreated and unseasonally warm temperatures contributed to heavy rains, which later froze the snow cover for months, cutting off the reindeer’s usual food supply of lichen and other vegetation.
“Reindeer are used to sporadic ice cover, and adult males can normally smash through ice around 2 centimetres thick,” says Bruce Forbes at the University of Lapland in Rovaniemi, Finland, who led the study. “But in 2006 and 2013, the ice was several tens of centimetres thick.”
This September saw the second-lowest level of sea-ice cover on record in the Arctic, and there is fear of another famine.
“If we see such events again this year, it could mean that they’re becoming more frequent,” says Forbes. “Now is the risk window, and if it happens again, it will be a major problem for traditional reindeer herders still suffering from losses in 2013.”
In both 2006 and 2013, ice in the Barents and Kara seas near the Yamal peninsula began to retreat in early November, a time when it normally builds up rapidly following the summer thaw. A lack of sea-ice cover led to soaring evaporation and humidity. This, combined with unseasonal warm air temperatures, led to abundant formation of rain clouds.
Prevailing winds blew the clouds over the southernmost tip of the peninsula, where indigenous Yamal Nenet herders were leading huge reindeer herds south. Torrential rain for 24 hours left all snow cover in the region sodden.
But within hours, temperatures plunged to -40 °C for the rest of winter, suddenly turning the waterlogged snow into impenetrable, solid ice for months that prevented feeding.
In 2013, these events led to the starvation of 61,000 of the 275,000 reindeer on the peninsula. “Losing 22 per cent of the population has never happened before,” says Forbes.
In 2006, about 20,000 of the animals died. More perished in 2013 because the impenetrable ice covered an area of 27,000 square kilometres from coast to coast. In the earlier year, the herders had some leeway because unfrozen corridors remained along both coastlines.
A repeat of such conditions this year could mean a double blow for reindeer and herders on the peninsula, because a huge cull of 250,00 reindeer is planned this Christmas to deal with claimed overgrazing issues and stamp out an anthrax outbreak in the animals.
This spread anthrax to other reindeer and, ultimately, to herders and their families, leading the Russian authorities to order emergency culling and vaccination of reindeer in the region.
Other Arctic researchers said the findings reinforced concerns about the potential impacts of reduced ice cover on wildlife and traditional Arctic communities.
“This is just another example of the interconnections between the various components of an ecological system,” says Peter Pulsifer, leader of the ELOKA project, which works with indigenous people to preserve local knowledge of the Arctic. “We’ve heard many concerns from residents on the potential impact of many kinds of environmental change on life and livelihoods in the Arctic.”
“This study serves to underline the fragility of Arctic ecosystems, and how sensitive Earth’s climate can be to changes in ice cover,” says Ed Blockley, lead scientist of the Polar Climate Group at the UK Met Office Hadley Centre in Exeter.
“Sea ice is an important component of the climate system because it regulates the transfer of heat and fresh water between the ocean and atmosphere,” says Blockley. “Although most notable in summer, Arctic sea-ice cover is declining in all seasons, and in the winter this decline is highest in the Barents and Kara seas in the Atlantic.”
Journal reference: Biology Letters, DOI: 10.1098/rsbl.2016.0466
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