Concerning satellite observations show major cities on US East Coast are sinking

[Admin]

Satellite images show major cities on the U.S. East Coast, including New York City, are sinking. This has caused concern among scientists.

Concerning satellite observations show major cities on US East Coast are sinking : Read more

 

[Unclear Engineer]

This is really just better measurements of something that is "old news".

The area I live in, the "Delmarva Peninsula" between the Chesapeake Bay and the Atlantic Ocean, has been measured to sink from about 2 to 5 mm per year for decades.

There are several reasons, acting at the same time, but mostly independently.

The most basic one is that this part of North America was not covered by an ice sheet during the last ice age, so it got pushed up as the heavy ice sheet pushed down the adjacent areas. Now that those ice sheets have melted away, this area is sinking back down as the areas where the ice once was are rising up. It is a slow process that is still going on.

But, on the Delmarva Peninsula, another factor is that large amounts of ground water are being pumped out to water crops (and now some golf courses). That also causes the ground to "settle" lower.

And, in some areas, heavy infrastructure has been built on land that is somewhat soft, and the road fills and buildings are sinking into the surrounding soils by perceptible amounts.

Where I live, the net effect has been about 6" difference in the local water level since about 1980. It is causing perceptible differences in the frequency and depth of the water on the road leading to my small community.

I expect that change rate to accelerate as global warming causes ice sheets in Greenland and Antarctica to melt faster and raise sea level faster. But, up until now, that has been merely half the total effect.

The benefit of the satellite measurements is that it help see the changes more accurately in real time.

But, I realize that the house I live in today will eventually be under water. This whole region has been underwater repeatedly over the last few million years, and I don't think it would stay above sea level even if humans were not affecting the environment. During the last interglacial period, the evidence is that sea level peaked about 25 feet higher than it is right now. And, at its lowest, about 25,000 years ago, it was about 325 feet lower than it is right now.

So, I think we need to start planning for dealing with the expected rise, and use the best data to help set the timing for scheduling our planned infrastructure modifications.