Hold on folks… the times they are a-changin’

Melting Arctic sea ice aims Frankenstorm Sandy directly at the Big Apple

Paul Beckwith,
B.Eng, M.Sc. (Physics),
Ph.D. student (Climatology)
and Part-time Professor,
University of Ottawa 

by Paul Beckwith

Frankenstorm Sandy is a scary beast. A hybridization between a tropical hurricane and a mid-latitude cyclone, her behavior is not natural at all. Moving northward off the east coast, Sandy is turning left toward land instead of right toward the sea. Sandy’s being blocked from moving north by a high pressure area of enormous magnitude, and being sucked west by a low pressure region of very exceptional (and highly unusual) strength.

Thus the designation “Frankenstorm”.

Because the Earth rotates on its axis, circulating air deflects toward the left in the Southern Hemisphere and to the right in the Northern Hemisphere. This deflection is called the Coriolis Effect and explains why storms in the northern hemisphere generally always turn to the right. Sandy should be turning right.

The Coriolis Effect - image credit: NOAA

So why is Sandy turning left towards the U.S. east coast? That’s where meteorology comes in - and the meteorology is now a lot different thanks to climate change. How so?

As I wrote in my last blog, push something and it moves a little … push it a little more and it moves a little more. This is called a “linearity” response. But sometimes a little push can lead to something totally unexpected! This is called “nonlinearity” and, contrary to what one might think, nonlinearities are inherent in most systems - like our atmosphere. Until recently, our atmosphere and oceans behaved like linear systems: incremental dumping of greenhouse gases into the atmosphere caused incremental changes, like rising temperatures and predictable rates of ice melt. But things are now changing unexpectedly fast – nonlinearity is kicking in! Make no mistake about it, Frankenstorm Sandy IS a nonlinearity event; totally unpredicted and totally unprecedented - the latest example of global weirding.

For the first time in at least 3 million years, the Arctic icecap will soon completely disappear. Without it, sunlight that would normally reflect back out to space will be absorbed by the water - warming it and the air above it. The old climate models predicted the Arctic Ocean wouldn't be ice-free for 30 years or more, but now we know it could be gone in as little as 3 years (and no more than 7). When this happens, the temperature differential (between the Northern and Southern hemispheres) will be reduced even further, and in short time.

NASA image with data from the U.S. Defense Meteorological Satellite Program’s Special Sensor Microwave/Imager.
The line on the image shows the average minimum extent from the period covering 1979-2010, as measured by satellites. 

Meteorology 101 shows us this change (reduction) in the temperature differential slows west-to-east winds and jet streams. And as fast jet streams slow, they become much wavier and travel much more north and south (this is contributing to the large high pressure area we are seeing directly north of Hurricane Sandy and large low pressure area over the United States).

If you think this storm is bad, get used to it. Frakenstorms like Sandy will become commonplace, the new norm, as it were.

As I write this blog for Sierra Club Canada, Frankenstorm Sandy maintains (and may even be gaining) strength as she approaches the U.S. coast. She’s expanded in size so much that gale force winds are now covering an area over 1500 km in diameter.

Sandy is now the largest hurricane ever recorded in the Atlantic basin. Her winds have reached 150 kilometers per hour and her barometric pressure has dropped to 940 millibars (among the lowest pressure ever measured anywhere in the continental United States).

As I’ve been predicting in my blog since August, hold on folks… the times they are a-changin’.

NOAA's GOES-13 satellite captured this image of Hurricane Sandy on Oct. 28 at 1302 UTC (9:02 a.m. EDT).
The line of clouds from the Gulf of Mexico north are associated with the cold front that Sandy is merging with.
Sandy's western cloud edge is already over the mid-Atlantic and northeastern U.S. (Credit: NASA GOES Project)

Originally posted October 29, 2012, at Sierra Club Canada; posted here with author's permission