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The little brightly colored Saturday Earthweek panel in the newspaper caught my eye today, as it often does: monkeys, or elephants, on the rampage, flooding, drought, ice-storms — all the weird weather highlights and animal response in one tight package. And this in particular: “Jet Stream Shift.”
The jet stream, as most of us know, is the enormous river of air, rushing from west to east at about 30,000 feet and up, which we ride for faster trips east, and our pilots try to avoid flying west. More importantly, it is the big player in our everyday weather. Storms, fair weather, heat and cold all are mixed, are shoved and follow this big, undulating air-born boa. And it’s shifting. What could this mean? Isn’t it moving all the time?
Yes it’s moving, as a dancer moves, but the dynamic average of its movement is shifting, away from the center (the tropics) to the edges (the poles.) Both the northern and southern jet streams are inching away from the tropics — which is to say, enlarging the tropics, moving the temperate zones north, making the north and south less arctic.
According to a paper published Friday in the journal Geophysical Research Letters the Northern Hemisphere’s jet stream moved northward on average at a rate of about 1.25 miles a year, 18 feet a day, from 1979 to 2001. The climate follows this movement. The tropics expand at this rate. The butterflies try to respond. The transitional vegetation gets less moisture, more heat: die or mutate. Life changes.
“Bascially look south of where you are and that’s probably a good guess of what your weather may be like in a few decades.”
This study follows other reports in 2006 that reversed the cause and effect but were recording the same phenomenon: the widening of the tropics, the dimunition of the poles — with effects already being felt in southern Australia, where as we have seen in recent weeks the 7th year of drought has contributed to alarming spikes in price of grains around the world.
Satellite measurements made from 1979 to 2005 show that the atmosphere in the subtropical regions both north and south of the equator is heating up. As the atmosphere warms, it bulges out at the altitudes where the northern and southern jet streams slip past like swift and massive rivers of air. That bulging has pushed both jet streams about 70 miles closer to the Earth’s poles.
It is not a case of a straight line poleward movement of increased heat, of course. The jet stream undulates, and is now undulating differently. Observers in England in 2007 and Southern California in 2005, of weeks of unusual torrential rain, pointed to unexpected and unexplained swings of the jet stream.
A Change In the Wind
Though none of the scientists involved in the observation and measurement of this movement can pin-point a connection to the larger issue of climate change, they are pretty sure the connection will be found. Meanwhile, the studies go on. The details are filled in. Citizens and governments notice more and being to connect local conditions to larger patterns, call for response. Will it be enough to change our habits and patterns or will they be changed for us by a changing world?