Loughborough: Before the end of this century, most of the Arctic will for the first time receive more rain than snow across a whole year. That’s one of the key findings of a new study on precipitation in the Arctic which has major implications – not just for the polar region, but for the whole world. While a reduction in frozen ocean surface is one of the most widely recognised impacts of Arctic warming, it has also long been anticipated that a warmer Arctic will be a wetter one too, with more intense cycling of water between land, atmosphere and ocean.
The shift from a frozen region towards a warmer, wetter Arctic is driven by the capacity of a warmer atmosphere to hold more moisture, by increased rates of evaporation from ice-free oceans, and by the jet stream relaxing.
The Arctic water cycle is expected to shift from a snow-dominated one towards a rain-dominated one during the 21st century, although the timing of this is uncertain. Now, a team of scientists have published a study in the journal Nature Communications which suggests that this shift will occur earlier than previously projected. The effect will be particularly strong in autumn, with most of the Arctic Ocean, Siberia and the Canadian Archipelago becoming rain-dominated by the 2070s instead of the 2090s.
Such a profound change to the Arctic water cycle will inevitably affect ecosystems on land and in the ocean. You might intuitively expect that a warmer and wetter Arctic would be very favourable for ecosystems – rainforests have many more species than tundra, after all. But the plants and animals of the Arctic have evolved for cold conditions over millions of years, and their relatively simple food web is vulnerable to disturbance.The new study underscores the importance of the global 1.5°C target for the Arctic.