Moscow has been as hot as Texas for a month. I keep looking at the forecast and it keeps looking like the forecast for Austin. This is wunderground’s forecast as of 2:45 PM my time on August 7 2010 (19:45 UCT I believe)
Of course, there are several reasons that 100 F (about 37.8 C) in Moscow is much worse than 100 F in Texas. Here in Texas it is not uncommon; hence both biota and people are used to it. We have air conditioning and heat-hardy plants. Moscow sits surrounded by areas that are normally wet, cool, clammy bogs, but now are dried out and fire-prone.
It’s around midnight in Moscow. The current conditions are listed as 82.6 F (28.1 C) and “smoke”.
Normal July high temperature is 73.8 F (23.2 C); August’s normal high is 70.3 (21.3 C).
Are the current events in Russia “because of” “global warming”? To put the question in slightly more formal terms, are we now looking at something that is no longer a “loading the dice” situation but is a “this would, practically certainly, not have happened without human interference” situation?
Can we phrase it more formally? “Is the average time between persistent anomalies on this scale anywhere on earth in the undisturbed holocene climate much greater than a human lifetime?” In other words, is this so weird we would NEVER expect to see it at all?
There are two approaches to answering this question. One is statistical (mathematical), and the other is integrative (based on experience and expertise rather than number-crunching).
The statistical approach would be to go over the observational temperature records of the past century until about 1980, looking for a comparable anomaly. We’d have to set some parameters in advance: duration, physical scale, amplitude. Then we could evaluate. If no such events turned up, we would remain somewhat uncertain, the record being too short. If several did, we could easily argue that this event by itself is too “normal” to be “caused by” “global warming”. On the other hand, we may well find that anything comparable occurred in the local winter; no summertime warm anomaly of this magnitude and persistence could be found.
Or we could argue that this is not an unusual “blocking” event; we have seen persistent meridional winds before. If you look at the pattern, you’ll see that it doesn’t actually stretch across the whole of Asia; there’s a cool zone in the middle between the two hot zones. Now we are asking whether we haven’t seen this particular flow pattern before. And I think that, in fact, will turn out to be correct.
Now we need to start talking about flow regimes and their connection to radiative forcing. And we’re getting a little abstruse and into territory that people who don’t know much about the atmosphere are lost. So they will try to drag us back to a proof of statistical significance. That’s climate politics. Anything you say will be held against you. What we actually want to do is identify a mechanism whereby shifted forcing could result in this unprecedented jet stream regime. That’s climate science; you’re allowed to raise difficult questions posed by observation, and propose approaches to answering them. (I’ll bet somebody will use a CGCM (“climate model”) to investigate this problem before all is said and done. What do you think?)
But right now I feel like hazarding a guess. As far as I understand, nothing like this has happened before in Moscow.
I refer you to this paper on heat wave (and cold snap) mortality in Moscow by Revich and Shaposhnikov. Therein a heat wave is defined as a period where the daily average temperature exceeds a monthly average in the 97th percentile at least 5 times, and of those exceeding the 99th percentile at least 3 times.
They end up with a threshhold of “extremely hot” of a daily average of 22.7 C (72.9 F) in July, the hottest month. Even the coolest day in our five day forecast is several degrees in excess of this. Today’s average temperature is is 29.8 C (85.5 F).
They mention in passing that the summers 2000-2005 were hotter than normal, at the 95 % level considering only July and August. They found an average of six days per month exceeding the threshold. “The heat wave of July 2001 was truly exceptional both in temperatures and in length.” they say. “In July 2001, daily average temperatures exceeded 25 C for 9 consecutive days (the norm is only 3 days per year). Maximum daily temperatures on these days always exceeded 30C.”
Let’s compare with a list of new daily records (via a recent comment here by Alexander Ac):
Note in particular seven daily high temperatures in a row, all in excess of 33.2 C (91.8 F). And all time records (not just daily records) have been set twice since then. So it seems reasonable to suggest that the conditions we are seeing are bizarre. (If anyone knows more, please chime in.)
The formerly remarkable heat wave of 2001, then, is “the sort of thing we’ll see more of” with global warming. But it may turn out reasonable, in the end, to say “the Russian heat wave of 2010 is the first disaster unequivocally attributable to anthropogenic climate change”. (I also ventured something like this about the Australian fires last year.)
“Given that this was the hottest day on record on top of the driest start to a year on record on top of the longest driest drought on record on top of the hottest drought on record the implications are clear…
It is clear to me that climate change is now becoming such a strong contributor to these hitherto unimaginable events that the language starts to change from one of “climate change increased the chances of an event” to “without climate change this event could not have occured”.
Photo lifted from Andrew Sullivan: Natalia Kolesnikova/Getty