But the long-term consequences of the ice loss are far more substantial and far more difficult to predict, says Masters. The reason? The jet stream, the fast-flowing river of air that helps to regulate temperatures and weather patterns across much of North America and parts of Europe.Many climate scientists believe the jet stream could change in major ways thanks to warming temperatures and shrinking ice in the Arctic. By moving cold and warm air around the earth, the jet stream helps even out its overall temperature. If the Arctic gets warmer, there’s no need for the jet stream to move as quickly as it does now.“If you’ve got more heat in the Arctic, the jet stream decreases in strength,” he added. “When the jet stream slows down, now that means that when you have an extreme period of weather, it tends to hang around longer.”

You might not think that what happens in the Artic has much bearing on what happens in Texas or Moscow or southern provinces of China, but a study published in 2012 in Geophysical Research Letters has drawn a convincing connection. Blowing around the periphery of the Arctic is the polar jet stream – a region of high speed wind that blows west to east, and helps drive wind circulation around much of the northern hemisphere.  The jet stream is powered by the temperature difference in fall and winter between the Arctic and the more temperate areas just to its south. But as the Arctic ice has receded, the Arctic Ocean waters have absorbed more heat in late summer and early fall.  In late fall and early winter, they’ve given that heat up, back into the atmosphere. That, in turn, has led to warmer Arctic autumns and winters, which has reduced the temperature difference that fuels the jet stream. The result is that the jet stream is now weaker than it once was – about 14% weaker than it was in 1980. Why does this matter? Because a slower jet stream makes it easier for ‘blocking’ weather patterns to develop.  Blocking weather patterns are the ones that hover over a region rather than moving on – like the drought that basted Texas in 2011 and decimated its forests and hay and wheat crops to the tune of more than $7 billion in damage, and like the heat wave that enveloped Moscow and much of the rest of Russia for most of the summer of 2010, killing an estimated 55,000 people in July and August of that year.

"We might change the pattern of the jet stream," he said, "might make it flow further to the north, and dip further to the south, be a more windy-twisty jet stream." That could generate more storms and even greater extremes in temperature.

The Arctic sea ice, essentially, it is a big reflector of solar energy during the summer, and that keeps the Arctic cooler than it normally would be. It acts like an air conditioner in a sense for the Earth's climate system. And that helps not only keep the Arctic cooler, but also the globe as well. And it's basically a sink for heat that comes in at the equator, gets transported to the north. And then you lose the heat in the Arctic. And those -- that transfer of heat from the equator to the poles, that essentially helps set up things like the jet stream, our prevailing winds, our weather tracks. And so as we start to lose the ice cover and we warm up the Arctic, essentially, that's changing the balance between the equator and the poles. And that will shift things like storm tracks and the jet stream, and that will change weather patterns.

“We’re in uncharted territory,” says James Overland of the University of Washington. The weakening jet stream means “wild temperature swings and greater numbers of extreme events”. The last time the Arctic is believed to have been ice-free is during the Eemian period, about 125,000 years ago, when global sea levels were between four and six metres higher than today. However, current atmospheric CO2 levels are already far higher than during the Eemian; indeed, you would have to go back several million years to find any era in the Earth’s history to match today’s levels of this powerful heat-trapping “greenhouse gas”.Lags in the system mean that we have so far experienced only the very mildest of the effects of the ever-growing heat imbalance in our climate system.

What climate change does is make many "natural" events more frequent and worse. By continuing to pump millions of tons of carbon pollution into our atmosphere every single day, we are throwing Earth's complex climate system out of whack, and this is the price we pay. Science tells us that the destructiveness of this storm was fueled by climate change -- driving higher sea levels that pushed up storm surge, and higher ocean temperatures that contributed to the monstrous size of the storm and loaded extra rain into the clouds. Science has identified another powerful potential factor: The record-breaking melting of Arctic sea ice's impact on the jet stream may have created the block of high pressure above Greenland that drove Sandy west into the continental United States, rather than allowing it to spin off east into the North Atlantic, as most late-season hurricanes do.

Climate change is driving more extreme weather – by heating up the atmosphere, pumping more energy into storms, and heating the air to the point that it can more easily suck away moisture or concentrate it in one point.  As the planet continues to warm, all of those factors will increase, leading to more heat waves, more droughts, and more floods. And the changes to the Arctic, it seems, will exacerbate this, by slowing down the jet stream, and making it more likely that the extreme weather conditions that develop get locked in place, hammering the same regions for protracted lengths of time.

It is difficult to overstate the magnitude of what is now unfolding in the Arctic region. The Arctic ice cap used to cover 2 per cent of the Earth’s surface, and the ice albedo effect meant vast amounts of solar energy were bounced back into space from the bright white ice mass.Losing this ice, and replacing it with dark open ocean, creates a dramatic tipping point in planetary energy balance.“The extra radiation that’s absorbed is, from our calculations, the equivalent of about 20 years of additional CO2 being added by man,” Prof Wadhams said.With global carbon dioxide (CO2) emissions already spiralling far beyond the levels that scientists have warned present grave risks to humanity, the injection of a massive new source of additional energy into Earth systems could hardly have come at a worse time.

Arctic sea ice is an important component of the global climate system. The polar ice caps help to regulate global temperature by reflecting sunlight back into space. White snow and ice at the poles reflects sunlight, but dark ocean absorbs it. Replacing bright sea ice with dark ocean is a recipe for more and faster global warming. The Autumn air temperature over the Arctic has increased by 4 - 6°F in the past decade, and we could already be seeing the impacts of this warming in the mid-latitudes, by an increase in extreme weather events. Another non-trivial impact of the absence of sea ice is increased melting in Greenland. We already saw an unprecedented melting event in Greenland this year, and as warming continues, the likelihood of these events increase.

the complete meltdown of the Arctic could roughly double the rate of warming of the planet as a whole.