If you live in northern NE United States or Maritimes Canada, in a sense you have just been through a "sort of" hurricane - an Extra Tropical Winter Cyclone
. The centre of this (most recent) low-pressure cyclone that's been hovering off New England and over Nova Scotia had dropped to 968 millibars and perhaps lower in isolated places. What does this actually mean?
(Click on image to see higher-resolution version, click again for downloadable full size)
Earlier that afternoon… when the pressure was at 978 millibars and dropping… I thought I'd investigate and learn what compares to it historically. (5
Typhoon Magi- 2010 Category 2 (978 millibars)
Hurricane Paula - 2010 Category 2 (981 millibars)
Hurricane Richard - 2010 Category 2 (978 millibars)
Hurricane Tomas - 2010 Category 2 (982 millibars)
Hurricane Carlos - 2009 Category 2 (978 millibars)
Hurricane Hannah - 2008 Category 2 (978 millibars)
Hurricane Edith - 1963 Category 2 (978 millibars)
Hurricane Four (before naming) - 1940 Category 1 (978 millibars)
Add to those some recent large North American winter cyclones - ie. 1 February 2010 Mid-Atlantic snowstorm (41 deaths - 978 millibars); 26 October Mid-West & Chicago Storm (960 millibars); as well as the Great 1975 Midwest Storm (wreck of the Edmund Fitzgerald - 978 millibars) and the unexpectedly huge and wet New England/New York storm of 1992 (with flooding of Vermont's capitol city Montpelier - 978 millibars).What's in a number?
Well, 978 millibars (or hundred-Pascals) equals 29" of barometric mercury pressure. Translated in real word terms on the ground - "A peripheral pressure observation of 978 millibars is equivalent to 75 knots based on the Atlantic pressure-wind relationship (Landsea et al. 2004)... discussing the 1850 Category 2 hurricane hitting Georgia, South and North Carolina, 24-25 August 1850 (1
So those big winds out there (and growing) can get really, actually scary. And on the ocean or close to the ocean, those are especially destructive. The present barometric pressure, dropped now to 968 millibars over Nova Scotia, is equivalent to some Category 2 and 3 hurricanes which have wrought huge destruction on North America.
Similar storms are now arising frequently off Greenland, and work their way quickly between Iceland and the UK/Ireland where they spin up to great speeds in excess of 100 knots in continuous winds. Over the past five years these have brought Scotland, England and northern Ireland to a near-total halt.
Strictly speaking, it is not just the absolute pressure of the Low but also how "tight" it is which determines wind speed… and the adjacency of a countering High pressure "pushes the gradient" so that each spinning whirlpool (downward and clockwise in the case of a High, and upward and counter-clockwise in the case of a Low) acts almost like a waterwheel… spinning the adjacent air. Where The Cold Comes From
See the isobars map I'm posting from 27 December with some highlighted high and low pressures (and their direction of travel). There are some particularly impressive reinforcing effects across the Arctic "helping" this storm over Nova Scotia.
It is like watching adjacent gears in motion, pinwheels whirling in the air - only in this case it is the "pinwheels" which are whirling the air and not so much the other way around, although the Coriolis effect in the northern hemisphere is contributing to the energy by giving the downward-spiraling Lows a counter-clockwise spin - like water going down a drain.
If the Highs and Lows are close together, they work together even more destructively… each spinning on opposite sides of a column of southward-moving or northward-moving air. On the westward side of Low (cyclone) the airflow is southward
in the winter northern hemisphere, carrying ultra-cold air south from Greenland. Much of this air is already sub-zero in temperature and comes from the heart of the Cold.
Where the Cold Comes From is pretty clear. Why the cyclones in wintertime are spinning so fiercely - with the fury of summertime hurricanes - is still not fully understood. The UK is getting stormier during winters, and the Gulf Stream's NEAW (North East Atlantic Water) warm current is slowing down. It used to be thought that to achieve the ultra-low barometric spins of hurricanes, the storm had to build over warm water. That clearly is not the only case.Can The Warm Go Away?
We do rely on the warmth of the mid and northern Atlantic to warm us here in eastern North America, as well as in western Europe… just as much in the winter as in the summer.
If the NEAW were to stop, the North Atlantic would turn into an icebox (along with regions adjacent to the ocean like western Europe, UK/Ireland, Iceland, New England and the Canadian Maritimes). Ironically, warming of the glaciers of the far northern Arctic and southern Antarctica may leave us with "no summer" in parts of the northern hemisphere. Warmer atmosphere means a colder North Atlantic.
This kind of abrupt "turn-around" of winter climate has
happened once and most likely three times before, during the Holocene - about 12,800 years ago and again about 8200 years before present (BP). At 12,800 BP there may have been a obscuring cloud hanging over much of the earth for decades, following a series of devastating comet explosions, meteorite impacts and vast incinerating fires (the likelihood of this is still being debated by some).
If curious search "Carolina Bays" or "Younger Dryas Extinction Event" for all sides of this debate.
In 8200 BP (preceded by the rising-ocean flooding of Norway's once-dry tundra plain and the release of its stored methane) there was a rapid warming of the atmosphere, an increased melting rate of the Laurentide Ice Sheet (still covering a lot of Canada) and the Greenland Ice Sheet; and eventually another torrent of glacial meltwater into the E. Greenland to Labrador current… desalinating the North Atlantic Deep Water (NADW), reducing the thermohaline "pump" enough the NEAW to finally collapse. (3
Recent research (2
) shows now that in the earlier 12,800 BP episode, the severe cold spell lasted for 110 years.
As for 8200 year "cooling event," my own coarse study of ocean sediment indicates that the NEAW warm current stayed "shut off" for about 85 years, beginning in the century of 8200 years BP. There was no summer after that - but rather, life was freezing all year in regions adjacent to the North Atlantic.
Because this was accompanied by a just-previous rapid rise in sea level, many formerly inhabitable areas of Europe (for instance "Doggerland" - now mostly under the North Sea) became bitterly cold as well as wet - basically uninhabitable… a "gods-forbidden place" especially when these challenges were soon followed by the daunting (and related) tsunami from the collapse of part of the Norwegian coastal shelf. (4
) Most archaeologists just beginning to look back at myths (and realising they aren't myths at all) are finding coastal settlements under several metres of water whose inhabitants must have suffered terribly.
Only when the Laurentide ice sheet had melted almost completely, the former Lake Agassiz was drained, and the current Great Lakes and St. Lawrence drainage system established did the Gulf Stream's NEAW re-assert itself. Summer came back, and people could survive in the coastal northlands again. Moreover, all the methane released by Norway's former tundras had been exhausted and the atmosphere had stopped being so warm.
This "8200 Cooling Event" plunging the overall temperature up to an average of 5° C in some places. The cooling change in 12,800 was also extremely rapid and even more severe - over a matter of weeks… not years… and brought the average temperatures down even more. Wooly mammoths found frozen with buttercups in their stomachs proved not to be an exaggeration of some paleobiologist, but the aftermath of a horrific blizzard and permanently-dropping temperatures in the middle of what was once "springtime." Creatures froze in their tracks.
A similar and relatively recent "cooling event" lasting more than 30 years also followed the springtime 1159 BC eruption of the Icelandic volcano Hekla, when the Sun was completely blocked from view for three years in most of Europe, Asia and North America... summer and winter… and caused almost universal mortality through starvation (or fluoridosis) in most of central and northern Europe. (personal research)Are We Headed There Now?
The caution for us now, is that today (and tomorrow) our case is just a bit different and in some ways worse than it was 12,800 and 8200 years ago.
The polar regions of the north hemisphere are today warming much
faster than the equatorial lands, even if one hears seeming un-scary news that the global climate is "only" one degree or two degrees warmer than in the past.
Yet already on average some northern Siberian, Canadian, Russian and Alaskan tundras are 6° C warmer
than back in the '50's and before… and once again those regions (and the northern seabeds) are bubbling off increasing large amounts of methane. This gas, mixed with the carbon-loaded atmosphere, will trap heat much more efficiently than CO2 - and once again will force the heating of the lower atmosphere. That in turn will provide more accelerated heating of the northern latitudes - to melt more tundra, down further into the methane-clathrate rich permafrost… around and around.
This is a closed-loop feedback system with increasing negative outcomes for living species, as well as (of course) changing the movement of ocean currents, and of air currents in the atmosphere. Some of this has never been seen before… so there are only speculative models of where it will go from here -- if we don't stop over-warming the planet.
While many advocates like the slogan "Stop Global Warming," to my mind, this is much too abstract. I'd say we should set our sight on actions and changes to accomplish the specific goal of "Stop Melting the Tundra Permafrost!
Any other course will leave us completely without options for recovery. This is one tipping point we don't want to tip over.(This article reflects some original research and theoretical modelling of Holocene climate-forcing sequences by Michael Cerulli Billingsley, Research Consultant for the Irish Spiritual Heritage Association and member of the International Permafrost Association, Royal Astronomical Society of Canada and the American Geophysical Union amongst others.)
1. Historical Climate Variability and Impacts in North America
, Lesley-Ann Depigny-Giroux and Cary J. Mock, p. 89 (Springer, 2009)
2. "Big Freeze Plunged Europe into Ice Age in Months" (NASA Earth Observatory) - William Patterson et. al, presented at the 2009 BOREAS conference, Rovaneimi, Finland at http://earthobservatory.nasa.gov/Newsroom/view.php?id=41518&src=eoa-manews
3. "The 8.2ka cooling event related to extensive melting of the Greenland Ice Sheet" - H. Ebbesen, A. Kuijpers, M. Moros, J. Lloyd, M.-S. Seidenkranz and S. Troelstra, Climate of the Past Discussions vol. 4 (2008) pgs. 1219-1235 athttp://www.clim-past-discuss.net/4/1219/2008/cpd-4-1219-2008-print.pdf
4. "The catastrophic final flooding of Doggerland by the Storegga slide tsunami" - Bernard Weninger et al., Documenta Praehistorica XXXV (2008) at http://arheologija.ff.uni-lj.si/documenta/pdf35/weninger35.pdf
5. List of Category 2 Hurricanes (with minimum pressures) - posted by "HurricaneStriker" on Storm2k at http://www.storm2k.org/phpbb2/viewtopic.php?f=42&t=110009
Hurricane Sergio (2006): 965 mbar
Hurricane Michael (2000): 965 mbar
Hurricane Hector (2006): 966 mbar
Hurricane Lane (2000): 967 mbar
Hurricane Juan (2003): 969 mbar
Hurricane Nora (2003): 969 mbar
Hurricane Elida (2008): 970 mbar
Hurricane Paul (2006): 970 mbar
Hurricane Otis (2005): 970 mbar
Hurricane Hilary (2005): 970 mbar
Hurricane Irene (2005): 970 mbar
Hurricane Marty (2003): 970 mbar
Hurricane Jimena (2003): 970 mbar
Hurricane Ignacio (2003): 970 mbar
Hurricane Douglas (2002): 970 mbar
Hurricane Humberto (2001): 970 mbar
Hurricane Aletta (2000): 970 mbar
Hurricane Carlos (2009): 971 mbar
Hurricane Flossie (2001): 972 mbar
Hurricane Ida (2009): 975 mbar
Hurricane Gil (2001): 975 mbar
Hurricane Richard (2010): 978 mbar
Hurricane Paula (2010): 981 mbar
Hurricane Tomas (2010): 982 mbar
6. Additional pick-up reading (no light task). I just came across this book-length research project, and became immediately intrigued. Dan Dorritie's "Killer in Our Midst" - http://www.killerinourmidst.com/index.html#anchorContents
He reviews the past 20k-plus years of climate change and the implications, especially with regard to methane... well thought through... for our immediate future.All original writing (cc) Creative Commons limited copyright (share with attribution) 2010 Michael Cerulli Billingsley