Issue: November 2012
BYPOINTS: On the Rise

Like everyone else on the hospitable shores of the Chesapeake, we at CBM have had one eye on the issue of rising sea level for quite some time now. Perhaps a closer eye than most, given our journalistic responsibilities, our sense of duty to inform you of . . . oh, you know, little day-to-day things like the complete transformation of the Chesapeake Bay coastline! Eek! Run for your lives!

Okay, it’s not that urgent. And to say it is would be even more ridiculous, if only slightly, than insisting that sea level rise is not happening at all, that it is some dastardly government conspiracy designed to make us all move away from the shore so they’ll have somewhere to land their black helicopters. But of course sea level is rising, and has been for a long time, as Marty LeGrand explains in her superb feature article in this issue, “That Sinking Feeling” [see page 22].

We’ve given it that title for a very specific reason—and an aspect of the story I hadn’t really tuned into until Marty’s article landed on my desk. Here on the Bay, she tells us, not only is the water rising; the land is sinking at nearly the same rate. A significantly greater rate in some places. That’s mostly because of something called glacial bounce, the phenomenon of the land surface gradually returning to its pre-glacial contours, even after all these millennia.

Officially this is called subsidence (perhaps because “glacial bounce” sounds like a brand of fabric softener) and it is responsible for about half of the six inches of relative sea level rise we’ve seen on the Bay over the last century. If things were to continue this way, we’d have nothing to worry about, at least not for three or four centuries. But now there’s this pesky climate change thing, specifically the warming and expansion of ocean waters, which has accelerated the sea level side of the equation. Conventional scientific wisdom, Marty says, is that we’ll see a sea level rise of two to five feet on the Bay over the coming century.
Thanks to the Maryland Department of Natural Resources and its online Coastal Atlas (dnr.maryland.gov/ccp/coastalatlas) you can get a very good sense of how that two to five feet of extra water would reshape at least the Maryland portion of the Bay. In some places the change would be negligible; in others, like Blackwater National Wildlife Refuge and lower Dorchester County, the loss of land and marsh would be measured in square miles. Many square miles—as you can clearly see on the atlas excerpt on page 25.

That before-and-after snapshot, like all the others that accompany the article, shows an inundation of up to five feet. The atlas also allows you to see, among many other overlays, what five to ten feet of inundation would look like, but I thought it best to show the more conservative overlay, so as not to be alarmist. And by that I mean that it alarms me. At five to ten feet, one corner of the CBM office here in Annapolis would be in Back Creek. It’s only the circulation department, so it’s not really my problem. But still, eek.



 

Tim Sayles, Editor