The original version of this post was published almost exactly 4 years ago (2010-01-11) when extreme storms and snow caused havoc in Western Europe. Given that many of the same “so where’s your global warming now?” gotcha tropes are flying around again since the severe cold weather hit Northern America, it seems like it needs repeating (with some minor updates). Scroll down for new links to articles elsewhere explaining recent extreme weather events (including the difference between this year’s polar vortex collapse and 2010’s shift of the jet stream).

Snow covering the UK, satellite photo January 2010

I knew that people would look at the extreme winter weather currently blanketing the Northern hemisphere and start saying ridiculous things about global warming.

Not one of them seems to realise that the only thing that has ever stopped the UK (and other nations around the North Atlantic) from having the same winters as Moscow (at a similar latitude) is the twin effects of the oceanic Gulf Stream (North Atlantic Conveyor) and the atmospheric Jet Stream over Europe, both bringing warm water and warm air currents from subtropical areas of the North Atlantic.

The 2010 winter whiteout was because the Jet Stream has shifted south. Shifts in air currents are a predicted effect of global warming, and since these currents help distribute equatorial heat to the poles, it is totally consistent with the science of global warming that changes in these air currents will lead to less effective thermal redistribution and thus colder winters at higher latitudes.

THE GLOBAL OCEAN CONVEYOR—The global ocean circulation system, often called the Ocean Conveyor, transports heat throughout the planet. White sections represent warm surface currents. Purple sections represent deep cold currents. (Illustration by Jayne Doucette, WHOI)

If they think this is counterintuitive, wait until the Gulf Stream shifts and/or shuts down. The atmospheric/air currents are largely dependent upon the oceanic currents (aka the Global Ocean Conveyor) that carry warm water away from the equator to the poles. The effects of global warming on the oceanic thermohaline circulation that drives these currents (and particularly the Gulf Stream) are being studied in increasing detail and abrupt shifts in its force, extent, (and its eventual cessation altogether) have happened in the past and are predicted effects of global warming (more fresh water from icecaps and glaciers entering the Northern oceans leads to less salty oceans leads to shutdown of Oceanic Conveyors).

This winter will seem mild in comparison. And while Eurasia and North America freeze, the tropics will bake in drought. Climate chaos, not just climate change, will be what we have then.

Links for 2013-2014 extreme weather events:

• 2013 was the hottest year on record for Australia, with lots of records broken.
• 2013 was Australia’s hottest year, warm for much of the world
• The Paradox of Antarctic Sea Ice 2: Research vessel trapped by summer sea ice
• Factbox: What is a polar vortex?
• Here’s What The ‘Polar Vortex’ That’s Hitting The US Actually Is

I’m sure you’ll understand why this post has been placed on full comment pre-moderation.

Categories: culture wars, Science

Tags: blast from the past, climate change, climate science, extreme weather