Observer: Meteorologist Jennifer Francis of Rutgers University, New Jersey” “The Arctic is warming faster than any other place on Earth.””“”Arctic temperatures have increased at more than twice the global rate. You can see this in the sea ice in summer there. In just the three decades, it has declined by 40%. About 1.3m square miles of sea ice have disappeared. That is an astonishing amount of ice to lose and it shows just how much heating is going on up there. More to the point, that warming is now changing weather patterns across the northern hemisphere.” / How the warming of the Arctic affects our weather has much to do with the origins of the jet stream. Air in the tropics is warmer than the Arctic and it rises. As a result, the atmosphere there is higher than it is over the Arctic. “A gradient is created and air slides down this atmospheric hill towards the Arctic,” said Francis. “This flow of air, high up in the atmosphere, from the tropics to the Arctic, is the crucial ingredient in the creation of the jet stream. The world rotates from west to east, however, and that rotation whips up this northward flow of air that descends over higher latitudes and sends it flying east round the globe as the jet stream. Earth rotates from west to east and that is what drives the jet stream in the same direction. ….The trouble is that the gradient between the atmosphere in the lower latitudes and in the Arctic is being disrupted by global warming. As the Arctic heats up disproportionately, so does the atmosphere at the north pole and as it warms up, it rises. The net effect has been to erode the gradient between the top of the atmosphere over the tropics and the top of the atmosphere over the Arctic. Less air pours down towards the north pole and less air is whipped up by Earth’s rotation to form the jet stream. It is becoming less of a stream and is behaving more like a sluggish estuary that is meandering across the upper atmosphere at middle latitudes.”
Future Today
