There was something strange on U.S. weather/drought maps recently. The northern hemisphere, or "polar" jet stream was shown plunging down into Mexico. It was down where the sub-tropical jet stream is supposed to be.
Mexico. Not Oregon or even northern California but Mexico, a country that actually dips down into the tropics. I do tend to pay attention to the jet stream, especially when it heads north up toward Alaska. That tends to bring us warm, southern air and, in high summer, we get a high pressure cell that builds out in the Pacific off Vancouver Island that means hot, dry, sunny conditions - our respite from the Rain Festival we celebrate the other nine months of the year.
The northern/polar jet has changed. It's no longer the gently undulating air current of the past. It now swoops way up and way down and the increase in the north-south transition is slowing its west-east flow. That easterly flow has been what has brought moderate fluctuations in temperature and precipitation. The old jet stream was essential for modern agriculture. Today's jet stream, with its magnified amplitude, brings droughts here and floods there, searing temperatures here and freezing temperatures there. You get the picture, this is not a good thing.
The Poster Child nation for the new jet stream has to be Britain. 18-months back Britain was in the jaws of a severe drought. Rivers were drying up, their beds exposed to the sun. The country was facing a drought emergency. Finally that wave moved on and a new one arrived, this time bringing floods and temperatures ranging from miserably cool to utterly frigid. This Easter Sunday was Britain's coldest on record. Across the northern hemisphere, unpredictable extremes are the new normal.
"The persistence of the spring's grim weather is particularly striking
for it comes after a series of other extreme meteorological events in
recent years. Last winter, a severe drought triggered stern warnings by
the Environment Agency that water rationing and hosepipe bans would soon
have to be introduced – until several months of torrential rain
produced widespread flooding.
"Our weather, always unpredictable,
is now fluctuating on a grand scale and becoming increasingly hard to
forecast long-term. The challenge for meteorologists is to explain these
unexpected outbreaks of climatic unpleasantness.
"'There is no
doubt that the recent weather has been highly changeable – on both sides
of the Atlantic,' said meteorologist Nicholas Klingaman of Reading
University. 'We have blizzards and flooding. America has had droughts
and scorching temperatures.'
"'The Arctic is warming faster than any other place on Earth,' said
meteorologist Jennifer Francis of Rutgers University, New Jersey. '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
"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
"'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.'
"'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.'
"The effects of this meandering
are now being felt. As the jet stream slows, weather patterns tend to
stick where they are for longer. In addition, the modest waves in the
stream have increased in amplitude so that they curve north and south
more frequently, bringing more weather systems northwards and
southwards. Hence the cold conditions that have been brought south over
Britain and which have persisted for so long."
"Until recently, this mighty stream
of air flew round the planet, in a slightly wavy path, between 30 and 60
degrees north. However, times are changing – and so is our atmosphere."
Now, you might have thought that this sort of jet stream shift, not to mention our world's broken hydrological cycle, would have been on every leader's lips because these things are bound to play hell with your grandkids' lives. Yet, judging by the lipflap from the Liberal leadership candidates, these things don't exist or at least they're not important enough to debate. They've got plenty of time to discuss how we're going to extract, upgrade, transport and sell the world's highest-carbon, unconventional petroleum to world markets but none of them want to touch what strategies like that will hold for our grandchildren. The New Dems are no better and the Harper Cons are at least a couple of shades worse or perhaps they're simply more honest about bitumen-peddling in a modern petro-state.