The Arctic Has Barfed

I was scanning my blog stats the other day – partly to see if people were reading my new post on the Blue Mountains bushfires, partly because I just like graphs – when I noticed that an article I wrote nearly two years ago was suddenly getting more views than ever before:

The article in question highlights the scientific inaccuracies of the 2004 film The Day After Tomorrow, in which global warming leads to a new ice age. Now that I’ve taken more courses in thermodynamics I could definitely expand on the original post if I had the time and inclination to watch the film again…

I did a bit more digging in my stats and discovered that most viewers are reaching this article through Google searches such as “is the day after tomorrow true”, “is the day after tomorrow likely to happen”, and “movie review of a day after tomorrow if it is possible or impossible.” The answers are no, no, and impossible, respectively.

But why the sudden surge in interest? I think it is probably related to the record cold temperatures across much of the United States, an event which media outlets have dubbed the “polar vortex”. I prefer “Arctic barf”.

Part of the extremely cold air mass which covers the Arctic has essentially detached and spilled southward over North America. In other words, the Arctic has barfed on the USA. Less sexy terminology than “polar vortex”, perhaps, but I would argue it is more enlightening.

Greg Laden also has a good explanation:

The Polar Vortex, a huge system of swirling air that normally contains the polar cold air has shifted so it is not sitting right on the pole as it usually does. We are not seeing an expansion of cold, an ice age, or an anti-global warming phenomenon. We are seeing the usual cold polar air taking an excursion.

Note that other regions such as Alaska and much of Europe are currently experiencing unusually warm winter weather. On balance, the planet isn’t any colder than normal. The cold patches are just moving around in an unusual way.

Having grown up in the Canadian Prairies, where we experience daily lows below -30°C for at least a few days each year (and for nearly a month straight so far this winter), I can’t say I have a lot of sympathy. Or maybe I’m just bitter because I never got a day off school due to the cold? But seriously, nothing has to shut down if you plug in the cars at night and bundle up like an astronaut. We’ve been doing it for years.

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Snowstorms and Sea Ice

Cross-posted from NextGen Journal

“That’s some global warming”, Fox News proudly announced. “Rare winter storm dumps several inches of snow across South.” It’s cold outside, and/or it’s snowing, so therefore global warming can’t be happening. Impeccable logic, or rampant misconception?

It happened last winter, and again so far this season: unusual snow and extreme cold thrashed the United States, Europe, and Russia. Climate change deniers, with a response as predictable as Newton’s Laws, trumpeted the conditions as undeniable proof that the world simply could not be warming. Even average people, understandably confused by conflicting media reports, started to wonder if global warming was really such a watertight theory.

But sit and think about it for a minute. If it’s cold right now in the place where you live, that doesn’t mean it’s cold everywhere else. It’s simply not possible to look at your little corner of the world and extrapolate those conditions to the entire planet. There’s a reason it’s called global warming, and not “everywhere-all-the-time warming”. Climate change increases the amount of thermal energy on our planet, but that doesn’t mean the extra energy will be distributed equally.

That said, an interesting weather condition has been prominent over the past month, telling a fascinating story that begins in the Arctic. At the recent American Geophysical Union conference in San Fransisco, the largest annual gathering of geoscientists in the world, NOAA scientist Jim Overland described the situation.

Usually in winter, the air masses above the Arctic have low pressure, and the entire area is surrounded by a circular vortex of wind currents, keeping the frigid polar air contained. Everything is what you’d expect: a cold Arctic and mild continents. These conditions are known as the positive phase of the North Atlantic Oscillation (NAO), an index of fluctuating wind and temperature patterns that impacts weather on both sides of the Atlantic.

The negative phase is different, and quite rare: high pressure over the Arctic forces the cold air to spill out over North America and Eurasia, allowing warm air to rush in to the polar region. Meteorologist Jeff Masters has a great analogy for a negative NAO: it’s “kind of like leaving the refrigerator door ajar–the refrigerator warms up, but all of the cold air spills out into the house.” The Arctic becomes unusually warm, and the temperate regions of the surrounding continents become unusually cold. Nobody visually depicts this pattern better than freelance journalist Peter Sinclair:

So what’s been causing this rare shift to the negative NAO the past two winters? In fact, global warming itself could easily be the culprit. Strong warming over the Arctic is melting the sea ice, not just in the summer, but year-round. Open water in the Arctic Ocean during the winter allows heat to flow from the ocean to the atmosphere, creating the high pressure needed for a negative NAO to materialize. Paradoxically, the cold, snowy weather many of us are experiencing could be the result of a warming planet.

An emerging debate among scientists questions which force will win out over winters in Europe and North America: the cooling influence of more negative NAO conditions, or the warming influence of climate change itself? A recent study in the Journal of Geophysical Research predicts a threefold increase in the likelihood of cold winters over “large areas including Europe” as global warming develops. On the other hand, scientists at GISS, the climate change team at NASA, counter that extreme lows in sea ice over the past decade have not always led to cold winters in Europe, as 7 out the past 10 winters there have been warmer than average.

Amid this new frontier in climate science, one thing is virtually certain: global warming has not stopped, despite what Fox News tells you. In fact, despite localized record cold, 2010 is expected to be either the warmest year on record or tied for first with 2005 (final analysis is not yet complete). What you see in your backyard isn’t always a representative sample.

Why Is it So Cold???!!!!

Anyone who lives in the north-central United States, or most areas of Canada, can agree with me here: Spring and summer have been incredibly cold this year.

Yesterday, I asked a climatology prof that I know, “Is there a reason for this? Or is it just a fluke?”

There was a reason, as he explained. And it’s incredibly cool (to me at least) and in no way proves that global warming is all wrong.

Let’s help the story along with a map, courtesy of World Atlas (doodles and arrows are my own).

map

The jet stream (the black curvy line on the map) is the boundary between the cold polar winds and the warmer temperate winds. In the Northern Hemisphere, when the jet stream is south of you, your area will be cold. When it is north of you, it’ll be nice and warm.

The northwestern Pacific has been warm this spring and summer. This warmth is pushing the jet stream further north. BC is experiencing the effects of this change – it’s had unseasonably hot, dry conditions, which are aggravating their already-worrisome forest fire problem.

When the jet stream peaks northward, the prof explained, it has to follow that with a trough. The peak on the West coast was very strong, so the trough further eastward, in the continental US and Canada, has also been very strong. Areas as far south as Chicago have had many days where the jet stream is south of them, so they’re submerged in polar air.

So all spring and summer, the jet stream has been “stuck” in the (very approximate) shape you see above. As an El Niño just began, our area would usually expect a warm winter. However, should the jet stream stay stuck in this shape…..we might have a colder winter than normal. The Prairie winters are bad enough already. I can only imagine the “so much for global warming” comments which would happen if such a winter came to pass.

So, in a strange way, our area has been so cold because somewhere else has been really warm. This can’t prove that the Earth is warming, as no single event can.

But it certainly doesn’t disprove it.