Arctic Sea Ice hit the news two ways this week. One was simple enough – the winter refreeze of the Arctic moved fast, as expected. After all last year's summer melt-off was the largest ever, so the remnant ice pack had a long way to go to rebuild itself, if only thinly, during the dark winter. At its peak, which we just past, it was the 6th lowest in the instrumented record. The second is not so simple. A slew of news outlets wrote up the causative link between loss of Arctic ice and the outbreak of bitter winter and spring weather – cold and snowy – in parts of the world at more temperate latitudes including the US and Europe. One might instinctively think that a less-cold Arctic would also mean less cold and snow to the south as well.
I've read a lot of the stories on this second topic and none do a particularly good job leading readers to see a natural way for a warming world to include a rapidly warming Arctic that in turn would make the rest of us more frequently reaching for parkas and mufflers. But there has to be a way to wrap our minds around this meteorological switcheroo. Instead, most of the explanations are longer on jargon and technical detail than material to let a reader exclaim ah HA, now I get it.
For instance, on Monday in UK's The Guardian l, John Vidal reports scientists' belief that low Arctic ice has promoted "the massive snowstorms and bitter spring weather ..across Britain and large parts of Europe and North America." Okay. He also says that the faster-warming Arctic means a weakening, and more wandering path, of the jet streams that usually blow strongly east-to-west around the Arctic. This, a source tells him, "allows the cold air from the Arctic to plunge much further south. The pattern can be slow to change because the [southern] wave of the jet stream is getting bigger." One gets an idea, but more clarity please. Surely one can do better explaining how warming can mean nastier winter storms and low temperatures.
Similarly at Australia's ABC network, reporter Ashley Hall cites a weakening jet stream as the cause of all that cold in northern (but not Arctic) parts of the world, and lays the blame for the jets stream's flabbiness on the ice loss. But that's it. The story just says the ice loss is a cause for the blizzards to the south. I looked through the Q&A the reporter had with two weather and climate experts to find a solid explanation for why a warming Arctic would send freezing weather south. I found none.
At NBC News John Roach, a freelancer with weather a specialty, giave it a shot. Again, the story says that the lower ice extent over much of the year weakens the northern system of jet streams that circumscribe Arctic air masses, leadng to a course that wanders farther north and south. It also says, opaquely, that this means the jet "transports less warm air over the land from the oceans." Hmm. But how does this contribute to icy Arctic blasts over that land?
OK, your turn, LA Times. There Monte Morin writes the right lede: "Anyone forced to shovel their car out of a snowbank this winter might wonder just how it is a blizzard can occur in a warming climate. The answer, climate sicnetists say, may hae to do with record sea ice losses in the Arctic." But other than refer to the jets stream is now taking a more meandering path, and also to the tendency of those meanders far to the south to get stuck in one position, one gets little sense why the UK or northeaster USA have these bouts of blizzards.
Perhaps reporters need to look harder in the toolbox for a way to explain this. That means, to me, a powerful metaphor that simplifies things. A suggestion that I have not yet figured out how to turn into a one-liner is that Earth's Arctic is springing leaks, like a kitchen ice box with the door left ajar. Warm air is wafting into it, making it a bit less cold up there even in winter. That has to mean cold air is coming out so the rest of the kitchen gets a few cold drafts. The overall system may be getting warmer too, maybe the oven is on, but near the ice box it's colder even as it's warmer inside the thing. A meandering jet stream is like the partly-opoen icebox door. It drags cold air out and to the south, while on hte return trip it dumps warmer air near the pole. I haven't worked it out. Somewhere in this news burst, and in the science behind it, is a good answer to climate contrarians who like to chortle, during an unseasonal blizzard, "Global Warming HAH! Take that, Al Gore." One wants to shout back : "Yeah the Arctic is warmer but it is still freakin' cold up there – and a piece of it just hit us way down here."
*UPDATE: While writing this I sent an email to Steve Vavrus, a climatologist at U. Wisconsin-Madison and a prominent source for reporters covering this news. I asked him if my leaky refrigerator or ice box (refrigerators with their compressor and radiators on their backsides complicate the analogy) metaphor works. He replied late yesterday:
Thanks for sending along this analogy. I think it makes sense, because when the circumpolar jet-stream winds are very strong and flowing a straight west-to-east path, then the bitterly cold polar air tends to remain locked up in the Arctic (closed refrigerator door). When the waves weaken and meander, then this pool of cold air can spill out more easily toward lower latitudes (and, as you say, some warmer air from the south can more effectively travel into the Arctic to warm that region). Obviously, things are more complicated in reality than this broad-brush description, but I think your analogy captures much of the essence of our hypothesis.
A broad brush analogy that ignores a few details indeed. Those are a specialty of mine and of most science reporters.
- Climate Central – Andrew Friedman, Michael D. Lemonick: Arctic Ice Hits Annual Max and it's 6th Lowest on Record ;
- National Geographic News – Daniel Stone: Is Shrinking Sea Ice Behind Chilly Spring? ; Nice job, actualy, explianing how the dipsy-doos of the jets stream now take Arctic air farther south than has been the usual. But leaves out that on the return leg it takes more warmth up there (a nice positive feedback for ice loss).
Grist for the Mill: Nat'l Snow and Ice Data Center Media Advisory on Arctic Sea Ice Maximum Extent ;