I had a plan for this week’s post, I really did, but then Siberia had to hit triple digits, and Africa had to have a giant dust storm, and there is really no way I can fail to acknowledge either story.
Hot Time in the Old Town Tonight
The situation in Siberia is, briefly, that the region has been unusually warm for months, now, producing a string of unusual and worrying events, such as melting permafrost (a tank resting on what used to be stable permafrost tipped over, causing a major diesel spill) and a big jump in wildfire activity. That the small town of Verkhoyansk hit 100.4° F. on Saturday is just the latest of the weird news.
High north heat-waves are, all by themselves, not that unusual. 100.3° set a record, but 90° is not unheard-of for the region, especially inland–the interior of continents tend to have extreme temperature swings, and when the sun shines 20 hours a day or more in the summer, things can occasionally heat up. Although “Siberia hits 100°!” makes an attention-getting headline, the real story is not one hot day but an entire pattern of unusually warm weather, where heat waves not only get hotter but last longer and come more frequently.
It’s easy–and more or less accurate–to say “it’s because of anthropogenic climate change,” but I like to dig a little deeper, look at how the general trend of a warming planet connects to, say, one hot day in Siberia in June. I should be clear that since I am not a climatologist or a meteorologist, my digging is necessarily provisional. You should definitely read the sources I cite for yourself before you quote me. But I do sometimes notice things. For example, as much as we are told that specific weather events can’t be tied definitively to climate change, I often see what looks, to my layman’s eye, like just such a tie.
There are several reasons why the air might get hot in Siberia, and they can layer on top of each other.
- The average temperature, the baseline around which weather varies, is slightly but definitely warmer than it used to be.
- Polar regions are, in general, warming faster than the rest of the planet in a process called “polar amplification.” Basically, a region that’s covered in snow most of the time is going to be cooler than an otherwise similar region that isn’t, because snow reflects light that would otherwise warm the area. So the high north (and Antarctica) is not just gaining a more insulating atmosphere, like the rest of the planet, it’s also losing its reflective snow blanket.
- This particular spring was very warm, so the snow and ice melted unusually early. Summer got a head start, as it were.
- A high pressure system parked itself over Siberia and refused to move. Atmospheric systems that don’t move cause problems because their effects tend to be cumulative–a long-lasting heat wave has time to get very severe.
All four happened to occur at the same time this year, producing record-breaking heat. There is definitely an element of chance, there, but of this recipe for a hot day, the first two ingredients are obviously anthropogenic climate change. The fourth ingredient, slower-moving weather systems, appear to be caused by changes in the jet stream which are, in turn, caused by the melting of polar ice–also climate change, in other words. Apparently, experts are debating whether heat waves in the high north are increasing, and whether climate change is the cause. Perhaps I am missing something, here, but I can’t see why there is any debate.
Maybe I’ll have to do a post on that very question.
Dusty-Old Dust-Storm Is A-Gettin Me Down
Meanwhile, a plume of dust is blowing from Africa all the way across the Atlantic, causing serious air pollution in the Caribbean–and it’s
predicted to blow into parts of the mainland United States next weekend. Dust plumes from Africa are not all that unusual (there is even an African dust plume season, and we are in it), but this one is unusually big.
So is this a climate change story?
At first, it looks like it should be. Dust plumes capable of crossing the Atlantic depend on dry soil in parts of Africa (to provide the dust), dry air (so that the dust doesn’t wash out of the air), and, of course, strong winds moving in the right direction. An unusual event caused, at least in part, by drought sounds like it ought to be a sign of climate change.
Except that (some, not all) climate modeling predicts that the wind patterns that carry the dust west might change as the climate does, putting less African dust in Caribbean lungs in the future, not more.
Before anyone starts celebrating, though, it turns out that dust plumes interfere with hurricane formation, or at least that they might be interfering–I’m a little unclear as to weather the association has been observed or only predicted–through a variety of mechanisms including cooling the sea (dust blocks sunlight) and creating a strong temperature inversion that keeps storm clouds from building very high. So, interference with the dust plume could be just another way that climate change worsens Atlantic hurricanes.
Now, here is a thought–I remember hearing a…call it a rumor, a bit of tid I can’t at present substantiate, that Atlantic hurricanes were getting more frequent but similar storms in other basins were not, a disparity taken to eliminate global climate change as a possible cause. Now, since then, more information has come in, and the hurricane/climate connection appears much stronger. But if climate change really is reducing the African dust plume and in turn exacerbating the Atlantic hurricane season, that would be a mechanism whereby climate change could influence hurricane behavior in one storm basin more than others….
But in the meantime, what caused this year’s big dust plume? Apparently, western Africa hasn’t been that dry of late.