The planet is warming and sea level is rising. In fact, global average sea level has risen about nine inches since record-keeping began in 1880. But that’s an average. The actual change in sea level varies from place to place, even along the U.S. Atlantic coast.
Cape Hatteras in North Carolina has seen close to a foot and a half rise, while it’s been just a few inches in other places.
New research helps pinpoint why.
“The earth is, in some sense, still experiencing the end of the last ice age,” said Chris Piecuch, an assistant scientist at Woods Hole Oceanographic Institution and author of a new paper in the journal Nature.
When the last ice age ended, about 11,500 years ago, the large ice sheets that were weighing down the land in North America disappeared. That started a very slow process of land rising back up because the weight of the ice was gone.
“But at the same time, those peripheral lands, those regions around the edges that formerly were levered up as a result of the weight of the ice sheet, those areas are now sinking down,” Piecuch told Living Lab Radio.
One way to imagine this is like a see-saw. As part of North America rises up, another part is being pushed down.
“And the in the epicenter, if you will, of where that sinking is happening is right around Cape Hatteras,” Piecuch said. Maine, on the other hand, has had very little sinking and has even seen some rising up of the land.
Nailing down the precise rate of sinking is useful because it can give planners a better idea of what to expect in the future. It also takes one variable out of a very complex problem.
“By really precisely determining how much is this predictable piece, you can imagine removing or subtracting that off of the observations,” he said.
Then it’s a matter of seeing what sea level rise is left.
As it turns out, once you remove the see-saw effect from the last ice age, Florida has the fastest rate of sea level rise, not Cape Hatteras.
Piecuch and his colleagues are now trying to figure out why.
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