National Geographic: Global warming allegedly causes longer and more intense cold spells: also "human activity can be blamed for some 60 percent of the observed rate of [Arctic sea ice] decline since 1979"

Arctic Sea Ice Hits Record Low—Extreme Weather to Come?

The chief culprit? Global warming. The potential upshot? Longer and more intense extreme-weather events such as heat waves, cold spells, and droughts...In a new study, detailed recently in the journal Geophysical Research Letters, Stroeve and her colleagues analyzed nearly two dozen computer climate models to determine the extent to which global warming is responsible for the increasing shrinkage of Arctic sea ice.

Her team determined that human activity can be blamed for some 60 percent of the observed rate of decline since 1979, with the rest due to natural climate variability.

"If you run these climate models and you don't put in the observed record of greenhouse gases, none of them show the ice declining," Stroeve said. "None of them are able to capture what's happening today without including greenhouse gases." (Learn about the greenhouse effect.)
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"Many extreme weather events are associated with weather patterns that are stuck or moving very slowly ... including droughts, cold spells, heat waves," Francis said. (See a graphic of extreme-weather trends.)

"I would not be at all surprised to see another unusual winter around the Northern Hemisphere" this year or next.