Study finds climate change is making Arctic seasons more like south

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As the Arctic warms small melt ponds are forming over vast expanses, like the one shown here in the Chukchi Sea between Siberia and Alaska in July 2011. (POSTMEDIA / HANDOUT / CLARK UNIVERSITY)

Newly published research says climate change has already altered seasons in the Arctic to make them more like southern regions.

And while tundra plant communities are already becoming shrubbier, scientists behind the paper say there's no way to predict what's going to happen as the change continues.

"We are doing a strange experiment," said Ranga Myneni of Boston University, co-author of the paper published Sunday in Nature Climate Change.

It's long been known that climate change is proceeding more quickly in the Arctic than anywhere else — about twice the global average.

Myneni, one of an international group of scientists behind the research, decided to look at how that warming is happening. He and his fellow researchers found the effect was on the difference between the seasons.

The amount that temperatures change as the seasons pass depends on latitude, said Myneni.

"In any given year, you start with a horizontal line that's the temperature profile of the equatorial regions. Gradually, you build up a bell shape as you go further north."

But most of the warming that's happening in the Arctic is taking place in winter, with somewhat less happening in spring and fall and the least occurring in the summer.

"If you start warming the winters more, and the transitional seasons a little bit more, you're basically flattening out the bell shape," Myneni said. "The bell in the North is looking less like a bell shape."

In effect, he said, climate change is giving the Arctic the temperature profile of the south.

Using satellite data, the team found the change that's already happened is equivalent to about five degrees of latitude. They then averaged 17 different climate models to suggest that by the end of the century, Victoria Island will have the same temperature profile as Wyoming.

What effect that will have on the plants and animals of the North is anyone's guess, Myneni said. Shrubs are already growing further north.

Myneni points out that warmer temperatures don't mean more hours of daylight. Nor will they improve thin Arctic soils or prevent melting permafrost from destabilizing the land.

There are too many variables in play to guess what's going to grow in the North or how that will affect associated animals.

"The Arctic is a feast for two-and-a-half months," Myneni said. "There's a tremendous amount of food available."

Animals from birds to whales flock north to take advantage, but timing is everything.

"It's seasonality that is important," he said. "Once you change seasonality, the whole food web is connected to that. We could not predict what the next 90 years will hold in terms of biology."

More research on the future of the Arctic is needed to try and understand what's in store, said Myneni.