How the Greenhouse Effect Contributes to Winter Woes

By Jonathan Byrne

Reblogged from Cape Cod Bay Watch’s blog. Posted there by Karen Vale on January 13, 2014

Jonathan Byrne writes about the greenhouse effect, a complex natural process that plays a major part in shaping the earth’s climate and ultimately our daily lives. Jonathan is an earth and space sciences teacher at Weymouth High School, and a professional member of the American Meteorological Society. Climate change is one of his passionate interests (see his most recent publication here). 

I recently spent the better part of a December weeknight dislodging my vehicle from a hostile snow bank on Commonwealth Avenue in Boston. My plastic shovel was no match for the glacier beneath my wheels.  Aside from personifying a Don Quixote style quest, I muttered about media outlets and their naive spin about northeast snow storms “Looks like the coast is going to escape the brunt of the storm as the snow is expected to change to rain and cut down on the accumulation”!  Oh sure! Let’s break out the ol’ party favors and celebrate! Then we can all go out and shovel this virtual “ reduced accumulation” of cement before it solidifies and entombs our set of wheels until the spring thaw!  Then afterward we get to whip up a mean cup of hot chocolate and make an emergency appointment with our chiropractor!

As I tirelessly shoveled away my ice weary murmur shifted to the Industrial Revolution and greenhouse gases.  (Say what?)  That’s right! And I don’t mean the “greenhouse” where you might buy Auntie Mabel a cactus for her eightieth birthday. I’m talking about the enhanced greenhouse effect resulting from an atmosphere thickened by the burning of fossil fuels; the liquefied remains of our distant ancestors from Carboniferous period three hundred million of years ago.

So what does all this mumbo jumbo have to do with chipping away at a snow bank on snowy December night in Boston’s Back Bay? I though you’d never ask!

Pull up a chair and follow this chain of cause and effect if you will:  Greenhouse gases have warmed the mean terrestrial surface temperature by approximately 0.8 deg Celsius since the turn of the twentieth century, which has also warmed sea surface temperatures by approximately one degree Fahrenheit (natural cycles such as the Atlantic Multi-decadal Oscillation aside). Now when an old fashioned winter nor’easter comes roaring up the coast, and the winds shifts into the northeast across the relatively warm seas surface waters, the “boundary layer” (lowest several hundred meters of the atmosphere is warmed increasing the probability of a mixed precipitation event i.e. frozen mixed with liquid precipitation especially along the coastal plain.  (One can only ponder, perhaps even shudder over how the Pilgrim Nuclear Power Plant contributes to the warming of Cape Cod Bay through the channeling of billions of gallons of heated water i.e. over 32 degrees above the ambient temperatures filling 3,000 acres of Cape Cod Bay!).

However winter weather woes do not end there. The increased sea surface temperatures also contribute to the intensity of the precipitation through greater instability and evaporation; and also the magnitude of the storm system itself through steepening the temperature difference (or temperature gradient) between the cold sector to the west of the storm track and the warmer marine air to the east.

This in turn, strengthens yet another precipitation producing mechanism called the coastal front, or the convergence boundary between the warmer marine air and the colder air over the interior. This phenomenon typically gives folks living along and west of the route 495 belt bragging rights (or the cursing rights, depending on one’s perspective!) for the heaviest snow accumulations.

Nonetheless another daunting thought crosses my shivering mind as I do my best Ucorn Cornelius impression with my makeshift ice pick:  The downy flakes descending over my shoulders are also the product of a re- expanding polar ice cap.

You heard that right! A touch of the ironic enhances the mystery of the world I say.  We have approximately 53,400 square miles more ice covering Santa’s real estate (i.e. the Arctic) as compared to 2012. In fact according to the IPCC the rate of warming since 1998 has slowed to half the value as compared to the period beginning on 1951 up until 1998. Once again the ocean system is at least partially the culprit. As the Atlantic continues to linger in warm phase, the Pacific is cooling!  The bottom line is climate change is indeed just a little more complicated than spewing a few greenhouse gases into the atmosphere and making the terrestrial environment warm and toasty.

Stay tuned for future blogs from Jonathan.

The original post can be found at http://www.capecodbaywatch.org/2014/01/how-the-greenhouse-effect-contributes-to-winter-woes/.

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