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With 2019 on track to be one of the warmest years on record, a major new study reveals the impact of warming temperatures on Arctic vegetation, animal species, and human communities who rely on the stability of the Arctic food chain to survive.
The study, published today in Science Advances by an international team of researchers, reports that the Arctic has warmed by 0.75° Celsius in the last decade. By comparison, it has taken the entire planet 137 years to warm by nearly the same amount (0.8° C). With the Arctic feeling the brunt of global warming, major changes have been observed to its landscapes.
‘Vegetation in the Arctic initially responded to warming with an increase in productivity and a shift in dominant species,’ says Dr Marc Macias-Fauria from the School of Geography and Environment, University of Oxford. ‘Shrubs and grasses increasingly replacing mosses and lichens – the tundra is literally becoming taller. The problem with this is that a shrubbier tundra means decreased surface reflectance over large areas of the north. This causes incoming energy from the sun to be absorbed and stored more efficiently in the ground, which contributes to enhanced warming.
‘Moreover, the biggest issue with better insulated ground temperatures is that it heats up and thaws permafrost in the far north, which releases carbon trapped in the frost into the atmosphere, which further accelerates global warming. There is far more carbon stored in Arctic frozen soils than contained in all living vegetation on the planet, so this is a serious concern.’
Changes in the natural vegetation and soil conditions can have very large impacts on Arctic animal species. ‘As the Arctic warms, we see more southern species that traditionally have never lived in the Arctic moving northwards,’ says Macias-Fauria. ‘This disrupts habitats and the food chain. Changes in the flowering and greening of plants due to warming temperatures also affects the availability of food – pollinators and all animals in the Arctic depend on getting plants’ timings right to survive on the tundra. Plants in the tundra are the base that drives the terrestrial food chain, and hence they can potentially affect all animals living in there and depending on terrestrial resources.’
Even where food is available at the right times for the animals living in the Arctic, changes in weather patterns can have devastating effects. As the Arctic warms up, rain in winter becomes more common, which creates a layer of ice that prevents animals from accessing plant life under the snow. In 2013, a single bad winter event of rain on snow was enough to starve 61,000 reindeer in the Yamal peninsula in Siberia.
‘There are very hard-felt impacts on local livelihoods when an event like this occurs, in particular to people living off reindeer husbandry,’ explains Macias-Fauria. ‘A mass death event like the one in 2013 leaves many families with no source of income. Most local Arctic people fully or partly depend on gathering, hunting, harvesting and/or herding local animal and plant produce, and they are feeling these changes first-hand.’
The comprehensive report represents the efforts of an international team of 15 authors specialising in an array of disciplines in order to create a full picture of the effect of global warming on the Polar Regions. The study documents widespread effects on wildlife, traditional human livelihoods, tundra vegetation, methane release and loss of sea and land ice. They also examined consequences for the polar regions as the Earth inches towards 2°C warming, a commonly discussed milestone.
‘Under a business-as-usual scenario, the Earth as a whole may reach that milestone in about 40 years,’ says Dr Eric Post, lead author on the study from University of California, Davis. ‘But the Arctic is already there during some months of the year, and it could reach 2 degrees warming on an annual mean basis as soon as 25 years before the rest of the planet.
‘Many of the changes over the past decade are so dramatic, they make you wonder what the next decade of warming will bring. If we haven’t already entered a new Arctic, we are certainly on the threshold.’