Wednesday’s rainstorm dominated Maine headlines, setting a daily rainfall record in Portland with nearly 6 inches of precipitation and pounding Searsport with nearly 10 inches.
But for those who are still pumping out their basements or looking into insurance claims today — or even for those who dodged the proverbial bullet and are relatively dry — get used to all the water.
A 2012 study found that the frequency of “extreme” rain- and snowstorms — defined as those expected to occur no more frequently than once per year based on historical averages — has increased by 74 percent in Maine since 1948.
So, simply put, severe storms that your grandparents and great grandparents experienced maybe once a year growing up now happen about once every six or seven months.
While the regularity and types of severe weather events is changing in different ways almost everywhere, that uptick in heavy precipitation is most prevalent — by a longshot — in our little corner of the country. The Pacific Coast has seen a comparatively modest 6 percent in increase in extreme storms over that same time frame, while places like Ohio and Nevada saw climbs of between 26 percent and 36 percent.
In fact, scientists say that while extreme precipitation has become more frequent, it’s also common for long dry spells between them, and for one region’s drought — in places like the Midwest and California — to be another region’s deluge. So instead of occasional light or moderate rainstorms happening across the country, much of that total precipitation is being saved up for a few big, torrential blasts on the northeast.
Welcome to Maine: America’s monsoon capital.
So why is this happening?
That aforementioned 2012 report, released by Environment Maine but vouched for by UMaine and St. Joseph’s College scientists, found that the water content of the warming atmosphere is increasing at a rate of about 1.3 percent per decade.
So the atmosphere’s capacity to soak up moisture, like a big sponge in the sky, has grown. Storm fronts in the Northern Hemisphere typically carry from west to east. Instead of terrestrial moisture getting absorbed and rained back down again nearby in the short cycles we’d grown accustomed to over history, it’s now getting absorbed and absorbed and absorbed across the country, building a single mass of atmospheric moisture until it finally overflows in a single huge storm — often over New England somewhere.
Combine those torrents with what researchers determined was a dramatic five-inch spike in Casco Bay sea levels in 2009-2010 — yes, that’s five inches in two years — and we can reasonably expect more extreme flooding as well.
The increase in flooding in low-lying areas has not gone unnoticed. The Portland Society for Architecture, for instance, released a 2013 report estimating that a two-foot rise in sea level by 2050 would do $33 million in damage to current buildings along the city’s waterfront Commercial Street, and that four feet in sea-level rise by 2100 would do $111 million in damage.
For Maine’s farmers, while it’s certainly better to have water than to have drought, the all-or-nothing precipitation isn’t a great way to get it.
“We don’t need rapid rainstorms that come out of nowhere, we need gentle soaking rains that come at routine moments throughout the summer,” U.S. Rep. Chellie Pingree, D-Maine — herself an owner of a North Haven farm — explained at the time of the 2012 study. “Scientists tell us that global warming causes increased evaporations, that cause drought conditions in the middle of the country, and all of that evaporation gets dumped into a downpour that just becomes runoff. That’s not a successful way to run an agricultural system, and it’s not a good sign for any of us.”