Arctic could see explosive 'greening' in decades due to global warming, study says
Land within the Arctic Circle is likely to experience substantial "greening" in the next few decades as grass, shrubs and trees thrive in soil stripped of ice and permafrost by global warming, a study says.
Wooded areas in the Arctic could increase by as much as 52 per cent by the 2050s as the so-called tree line - the maximum latitude at which trees can grow - shifts hundreds of kilometres north, according to computer simulations published on Sunday in the journal Nature Climate Change.
"Such widespread redistribution of Arctic vegetation would have impacts that reverberate through the global ecosystem," said Richard Pearson of the American Museum of Natural History's Centre for Biodiversity and Conservation.
The Arctic has become one of the world's hotspots for global warming. Over the past quarter-century, temperatures there have been rising roughly twice as fast as in the rest of the world.
"These impacts would extend far beyond the Arctic region," Pearson said. "For example, some species of birds seasonally migrate from lower latitudes and rely on finding particular polar habitats, such as open space for ground-nesting."
In a separate study also published on Sunday, Dutch scientists say that ice shelves in Antarctica - another source of worry in the climate equation - have in fact been growing thanks to global warming.
Meltwater that runs off the Antarctic mainland provides a cold, protective "cap" for ice shelves because it comes from freshwater, which is denser than seawater, the team from the Royal Netherlands Meteorological Institute says.
Ice shelves are the floating blankets of ice that extend from the coast. They are fed by glaciers that move ice down from the ice sheet and towards the sea.
The freshwater acts as a cold coating for the underside of the ice shelf, cocooning it from warmer seas, according to their study, appearing in the journal Nature Geoscience.
This would explain an apparent anomaly: why sea ice around Antarctica has been growing, reaching the greatest-ever recorded extent in 2010, the study suggested.
Other scientists, asked to comment on the work, concurred that the phenomenon was one of several unexpected impacts from global warming, a hugely complex interplay of land, sea and air.
If confirmed, it does not detract from the broader trend - and source of concern - from warming, they say.
"This is a major, new piece of work with wide implications for assessing Antarctica's ice mass in the coming decades," said palaeo-climatologist Valerie Masson-Delmotte of France's Laboratory for Climate and Environmental Science.