I spotted a Facebook meme this morning that listed a rather startling number of places having unusual floods over just the past two weeks:
- Mexico City
The point, of course, was that to have so many floods in such a short period of time is a clear sign of global warming. On one level, that’s clearly true; part of what climate change means is that floods are worse now. But reality is more complex than any meme–for example, increased flooding can be caused by changes in land management as well as by changes in the weather. So, since I’d rather pass around detailed and verified facts than a meme that simply sounds plausible, let’s look into this, shall we?
As one might guess, all the floods in Europe are actually one flood; France, Germany, Belgium, Romania, and the Ukraine–plus Poland, the Netherlands, and Austria–have all been drenched by a series of slow-moving storms trapped above the continent by an omega block. An omega block is essentially a tight curve in atmospheric currents that keeps a weather system from moving for the duration. Exactly how, or even whether, the omega block might be connected to the greenhouse effect is not clear, but a warmer atmosphere holds more moisture and therefore can drop more rain from any given storm.
And there could be a link with the omega block. There was one with the polar vortex, after all.
In any case, is whether this weather is unusual. If Paris flooded every other week, this latest flood would be no big deal, except for the people who happened to be in the middle of it. I have not been able to find a detailed analysis of how often this type of flooding has occurred historically. What I have found is consistent with this event being a real story, if perhaps not as bizarre as it seems, at least in France.
Since record-keeping began in 1873, there have four severe floods in Paris, of which this latest is the mildest. In 1910, the Seine River crested 8.62 above normal (28′ 3″) and set the record. In 1955, the river crested at 7.1 meters (23′ 3″) and at 6.18 meters (20′ 3″). This year’s flood crested at “only” 6.1 meters (20 feet even). But, and this is a critical but, this year’s storms did drop more rain on France than any recorded storm has before.
While this flood didn’t break the Paris record, we can compare the number of record-breaking rainfall events from 1980 to 2010 with the norm over the previous 80 years–and the number is up by 12% world-wide. In Europe, it’s up 31%.
I actually haven’t found any reports of flooding in Pakistan over the last few weeks–though it’s possible that all the attention on Paris have messed with the search engine’s algorithms, that happens sometimes. Either way, apparently Pakistan flooded in April, though, so the country need not feel left out.
I have seen various articles referring to recent floods in eastern Russia, but I have not found any further information–except that Russia apparently also flooded in April.
Again, I have not been able to find any information, aside from the fact that serious flooding around Beijing has occurred recently. I am guessing that flooding in Taiwan was connected, however.
I have not found confirmation of flooding in Mexico over the past few weeks.
A Lot of Water
Sometimes I spend several hours researching a subject and find some great material. This was not one of those times. Basically, to recap, sometimes it rains a lot, and it’s happening more often because of climate change. Also, Facebook memes are not entirely reliable, but we need to do something about climate change anyway.
Just another day living with the new normal.