2013's extended winter being endured by the USA's north and northeast, and by England and Europe, is caused by the Arctic Ocean's warming. Global warming melts the ice and warms the sea, which changes the jet stream... which controls northern weather. During late summer and early autumn of 2012, a new idea came out of some climate modeling being done at the National Snow and Ice Data Center (NSIDC). To be honest, it had been floated before, but this was the first time it was supported by robust data and modeling. What was the thrust of this new idea? That the melting of arctic ice has reduced the sea ice to the extent that the open water is holding enough heat to affect the western leg of the jet stream, slowing and dissipating it. This is allowing storms normally carried rapidly on the back of a strong and fast jet stream across late winter and early spring land in northern America and Europe, to misbehave. They linger, pick up moisture and strengthen, and dump "late winter" blizzards days after the spring equinox.
But over the winter this notion seemed to be forgotten. Many major news media carried the stories in August, September and October of 2012. However, by March 15, 2013, when the maximum surface coverage of Arctic Ocean Ice occurred all seemed to be lost. No major news outlet was following up. Then came the solstice... and 2013's extended winter was upon the land, with freezing rain, sleet and blizzards. The storms meandered, they stalled, they moved in unexpected directions, they... dawdled. And winter hung on; cold, wet, miserable and unexpected. What on Earth was going on?
The Oceans are heat sinks.
At a Climate Nexus news conference held Tuesday, March 26, it was pointed out that sea ice is white and reflects heat, while sea water is blue and absorbs heat. The loss of ice has been going on for a very long time. Eighty percent of the volume of arctic sea ice has disappeared in the past 30 years... sucked into the battle to normalize the temperature of the water (slightly above freezing) versus the temperature of the ice (exactly freezing). In the process, the region of the world scientists call "the planet's air conditioner" has pretty much gone out of sync with the planet it's supposed to be air conditioning. The result? Extended winter. And it's going to get worse.
As recently as 2006, scientists were predicting the end of Arctic summer sea ice by mid-century. During the winter of 2012-2013, sea ice went from the lowest area on record, 1.3 million square miles, to 5.4 million square miles. But that nearly five times expansion still left the arctic ice at its sixth lowest level ever recorded. Worse, it's only a single year's ice, which means it is very thin, easily broken up and rapidly melted (breaking it into smaller pieces hastens the melt, of course, because the melt proceeds from all the edges). Storms have been hammering the arctic ocean these past few years right as the Ice begins to retreat, breaking it up. Now, scientists are saying summer ice stands a good chance to disappear entirely by late summer 2020.
The warmer the Arctic Ocean becomes the less effective and more erratic will become the air conditioning effects and storm mitigation effects of the planet's "air conditioner." Lingering winters and springtime blizzards won't be humanity's only challenge; challenges will include the diversity and constancy of what used to be occasional and scattered local climatological events -- droughts, temperature extremes and extended precipitation as storms stall and meander about.
It has been suggested that Earth is headed into another "little ice age," with weather like the world suffered through from AD 800 through the 1600s. That's doesn't seem likely. What does seem likely is that the Earth is headed into a period of erratic extreme weather which will include distorted temperatures and precipitation delivered in volumes and quantities that are unuseable at the time, and that do nothing for the future needs for water.
One final note... it is not true as deniers claim, that the planet has not continued to warm over the past fifteen years or so. As this article shows, the arctic air conditioner is not the only part of the planet on which global warming is playing havoc. The rate of warming sped up at the turn of the century, and has now returned to its original rate which is substantially slower. Nonetheless, the warming of the globe, in the air, on land and sea, continues apace.