Ellicott City, Maryland flooded again, about a week and a half ago (May 27th). We are not talking about a little water in the parking lots, here—for those who haven’t seen the coverage, the streets became rapids. I’ve seen video of cars flowing along in the water, their windshield wipers beating back and forth forlornly. I keep thinking about the people in those cars. The first floors of the buildings are completely gutted. At least one man has died.
The river crested at a record 23.6 feet after rising almost 18 feet in just two hours.
What makes the flood especially upsetting for locals is that a similarly catastrophic flood all but destroyed the town only two years ago. The community was just getting itself together again, and now they have to start over again.
Since 1768, Ellicott City has flooded 15 times. Not all of the floods have been catastrophic, but the town does get wet often. It’s not just bad luck; Ellicott is an old mill town, so of course it sits in a place with plenty of water power. Three streams converge here and flow into the Patapsco River, bringing all the runoff from a large, bowl-shaped valley straight through town.
But while Ellicott City has always been flood-prone, but they haven’t always been the same kind of flood. Traditionally, the problem was the rise of the Patapsco, meaning that the floodwater would rise up into the community. Now, the smaller streams also jump their banks, which is why recent floods have roared down through the town, turning the streets into rapids.
Development over recent decades has increased the area of impermeable surface in the watershed dramatically, making flooding much more likely. Also, of course, there’s climate change.
As readers may know, climate change in general increases the chance of extreme weather. Rain storms are both less frequent and more intense, so that areas with no net change in rainfall get both more droughts and more floods. And in the Northeast of the United States, or, by some measures, the whole eastern part of the country, rain intensity is increasing faster than anywhere else in the country. So, yes, repeat catastrophes such as Ellicott City has suffered are part of the new normal.
(Note that we’re talking about likelihood, not possibility: for the same location to get two 1000-year floods back-to-back, as Ellicott City has, wouldn’t have been impossible under the old climate regime, because “1000-year flood” doesn’t mean once per 1000 years, but rather a one-in-1000 chance of occurrence in any year. It’s unlikely, but entirely possible, to have several in a row. The issue is whether these really were 1000-year floods; climate change and development together may have changed the odds.)
In fact, recent flooding in Maryland (an identical weather pattern developed over Frederick two weeks earlier) may have a more direct connection to warming temperatures, although this information comes from an article arguing almost the opposite point. Apparently, we have been “stuck in a late July weather pattern, one in which the jet stream has built a ridge of high pressure over the Mid-Atlantic.” But because this was May and early June, the ocean waters are still cool. The combination sends unusually wet weather into Maryland. So, while the author was quite correct in describing all of this as a local weather event, something that could occur by bad luck regardless of climate change, it is a weather event caused by the atmosphere behaving as though July had come two months early—hotter, in other words.
Yes, weather is weather and climate is climate, and it’s worth bearing the difference in mind, but when unseasonably warm weather causes record-breaking storms, it seems disingenuous to say global warming is not at fault.
But disaster is never just about climate. Ellicott City is far from being the only flood-prone area in Maryland, but most flood zones aren’t aren’t also the busy centers of quaint historic districts. So putting a city in harm’s way, and then exacerbating the harm through risky development, is definitely part of the picture.
The other major issue is that Ellicott City has been studying its flood risk and fielding proposals for mitigation since the 1970’s. Not much has been done. One proposal offered after a flood in 2011 was actually rejected by town leaders as too expensive. They changed their mind after the 2016 flood, but the work hadn’t been completed yet before the place flooded again. This historical failure to act is having serious political consequences, now.
“Natural disasters” are always the result of a combination of extreme weather (or extreme geology) and human responses to those events. The scale of the tragedy is always either compounded or mitigated by the economic wherewithal of the affected people and by political decisions about acceptable risk, acceptable loss, and how much money certain people’s lives and livelihoods are worth.
And now, climate change itself is a result of decisions, both large and small, about who or what we are going to treat as important.