The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change


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New Year, New Normal

It’s cold.

What I mean is that the weather is colder than its been recently in the part of the world where I happen to be. The simple answer to those who insist the world can’t be warming while they personally shiver is that climate change involves increased extremes, including the occasional extreme cold snap. But it’s also possible for one area to have record-breaking cold even as the world on average is unusually warm, as has happened in recent years. And it’s possible for conditions to seem unusually cold even while still above the 20th century average, because we’ve grown used to warmer conditions still.

I haven’t checked to see which of these concepts applied to New Years’ Day in Eastern Maryland, 2018.

What I know is that I turned up on Assateague Island for the annual New Years’ Day Beachwalk, which my husband usually leads, and conditions were brilliant, bright, and beautiful. Clear, blue sky, a stiff breeze whipping the waves to photogenic whitecaps, and a windchill of seven degrees.

I want to emphasize that this event is not supposed to be masochistic. It’s not like the Polar Bear Plunge, in nearby Ocean City, where people actually jump in the water on the first of January, no, it’s an educational walk where you get to stroll along with a naturalist, learning about the island’s history, its sand, and its sea shells. Some years over three hundred people show up.

This year, we had 34 people, almost half of them organizers, volunteers, and hangers-on. My husband did his best, under the circumstances, but there was no shelter from the wind anywhere, and people were having trouble concentrating because it was just too cold. He cut the walk in half and brought everyone back to the starting point early for hot chocolate. Then he and I went home and had Chinese take-out.

Everything everybody says about cold snaps in a warming world is true–climate change involves extremes in all directions, it can be cold here but warm elsewhere, and these temps only seem as cold as they do because everything has been so warm of late.

But what happens when we get used to warm weather?

It’s not like I’ve never experienced single-digit temps before–I used to live in New Hampshire, where I regularly biked to and from school in the winter. Cold was normal, and seldom bothered me. I dressed for the cold as a matter of routine. But now…do I need a hat, or is a hood good enough? How thick do my socks need to be? How many layers do I need? I can’t quite remember. I’m out of practice. Give me another week or two of this and it will all come back to me, but Monday morning I wasn’t there yet.

Whether a given temperature is historically normal or globally notable is less important for most people than whether it’s been typical lately. A surprising cold snap in Maryland might involve temperatures that are perfectly normal for Vermont or New Hampshire, but that doesn’t mean the Marylanders have adequate coats, hats, and gloves, nor do they necessarily have lifestyles and habits that make sense in such temperatures. Where a New Englander might have recreational activities that require cold temps (like ice fishing), on the Lower Eastern Shore, this kind of weather disrupts everybody’s plans. Sometimes the surprising cold is dangerous.

The way changing climate works, cold weather doesn’t go away, it just gets less likely. While I haven’t seen any figures on the matter, I’m wondering if rising average temperatures are resulting in more disruption–and more danger–when cold snaps do occur.

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It’s *%@$ing Cold

Actually, no it isn’t, at least not where I am. I’ve just been outside and the air is definitely brisk, I’d want a coat if I stayed out long, but it’s not unpleasant and the day looks beautiful and bright. But it is noticeably colder than it was yesterday, and I understand almost all of the United States is in a cold snap right now.

Predictably, the Internet is chattering about a “polar vortex” again, as if the term simply meant an unusually severe cold snap. It doesn’t–the polar vortex is not a weather event but a current within the atmosphere. There is always a polar vortex; it is the southern boundary of the polar air mass. It’s basically another name for the familiar jet stream. Sometimes the jet stream is almost straight, a circle drawn around the northern part of the globe. Sometimes it is wavy, bringing cold air farther south in some places and warmer air further north in other places. Right now, the boundary between polar and non-polar air is extremely wavy, and it is colder in Texas than in Alaska. What this is, really, is a good old fashioned cold-snap, albeit one that extends unusually far south.

There are signs that this year the media may shift to “arctic outbreak” as their buzzword of choice.

The current cold-snap is a little different than last year’s, where the cause of the extremely wavy boundary was debatable but might have been related to melting sea-ice in the arctic. Right now, we’re looking at the effects of the former Super Typhoon Nuri, which formed in the Western Pacific, became one of the most powerful storms of the year, and then weakened and recurved, heading northeast. By the time it reached Alaska it had lost its tropical characteristics (meaning its structure and the way energy moves through the system were no longer hurricane-like) but retained much of its power. Last week, the air mass formerly known as Nuri was among the most powerful storms in the Bering Sea ever recorded. Pacific storms can and do interact with the jet stream, causing weather changes hundreds of miles away. In this case, Nuri caused the boundary to become extremely wavy, freezing Texas.

Probably, some climate skeptics are wondering about global warming about now, and while I haven’t seen it yet, I expect some deniers are going to advance this cold-snap as proof against climate change. In writing this post, I’m being preemptive.

Yes, cold weather can be a symptom of global warming. A warmer atmosphere is generally more active, more prone to extremes of all kinds. A destabilized, extremely wavy polar vortex specifically could well be more common now that the arctic ice is melting, and Nuri, like all tropical cyclones, has a link to to global warming through the rising temperature of ocean water. This year’s Western Pacific typhoon season has not been startlingly intense (except for the monstrous Super Typhoon Vonfong, which fortunately weakened before it hit anyone), but it has been stronger than average. The sea has also been exceptionally warm.

But there are a couple of other points worth bearing in mind:

  • It isn’t cold everywhere. Yes, the weather is unusually cold today in the eastern half of the United States, but there are other parts of the world and some of those parts are unusually warm. An unstable polar vortex doesn’t actually make the average temperature of the world drop, it just redistributes cold air. Last year, while the Eastern U.S. was freezing and questioning the existence of climate change, the same weather patterns were causing record-breaking heat in California, Alaska, and parts of Europe. The hot weather exacerbated the California drought and caused a dangerous avalanche in Alaska that completely cut off one town’s road access. For the people there, global warming was not in doubt.
  • Coldness is relative and we have been spoiled by warm weather in recent years. Although the current “arctic blast” may break some local temperature records, it feels a lot colder than it really is because we’ve gotten used to the new normal of warm temperatures. Much of what we saw last winter would have been quite normal twenty or forty years ago (yes, I did just cite the cartoon, XKCD, but the cartoon in question does cite its sources and its author is an actual scientist).
  • Global warming means cold weather is rare, not that it never gets cold anymore. Yes, there are going to be genuinely cold years going forward, probably including some record-breakers where the entire planet is colder than it has been since record-keeping began. The weather on Planet Earth is extremely variable, and that isn’t going to change. What we are seeing, and will continue to see, is that the cold snaps are fewer and less severe than the warm spells. On average, we’re going up. 

This year, we have been especially far up. May, June, August, and September each broke global heat records. I am not certain, from the wording of my sources, whether May, June, and August were each in turn the hottest month ever, or simply the hottest May, June, and August ever. In either case, the records were based on a global average, meaning that they included measurements from places experiencing Fall or Winter at the time. September was definitely the hottest of any month ever recorded. 2014 is likely to be the planet’s hottest year on record, cold snaps in the U.S. notwithstanding. This is a big deal.

Weather.com put the situation in startling perspective:

Earth hasn’t set a monthly record for cold since December 1916, but all monthly heat records have been set after 1997.