Why spring is so cold

As Northern Hemisphere temperatures remain below normal more than a week into the official start of spring, a team of meteorologists and climate scientists are pointing to recent research that suggests sea ice cover is a likely culprit.

Recent imaging from the U.S. National Snow and Ice Data Center showed a historic minimum in Arctic ice cover last fall, and current data reveals that sea ice cover-which recently reached its maximum for the year-is at its sixth lowest extent in the satellite record.

Less Arctic sea ice-which is caused by global warming-alters atmospheric circulation in a way that leads to more snow and ice, said climate scientist Jiping Liu, who led a 2012 study on the topic published by the Proceedings of National Academy of Sciences.

It's a tough thing to understand. Less ice at the top of the world, often considered the planet's thermostat, might normally signal warmer global temperatures, not colder ones.

But the way weather works isn't so simple. Without a substantial ice cover, Arctic wind is less constrained. The jet stream-the belt of cool air that regulates weather around most of the Northern Hemisphere-then dips farther and farther south, bringing cold air from the Arctic closer to the Equator, Kazinform quotes National Geographic.

The result is much colder weather dipping into the spring much longer, and more forcefully, than normal.

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