Monday March 11, 2013 | 10:21 AM
Posted by Harold Johnson

No beach or coast in the world is a static thing.

Coastlines are always changing and evolving. Some are “depositional,” meaning that sediment is being added faster than it’s being taken away. Others are “erosional,” where sediment is being removed faster than it's replenished.

Whenever a house -- or town -- is built on the beachfront, the ocean waves are going to move naturally farther from it each year, or closer.

It’s always true, but it becomes more viscerally true after a storm.

Lately, the pace of that evolution has increased. We are living in a warming world. Which makes it an age of rapid sea-level rise & coastal change.

(Image from NOAA’s Sea Levels Online site*)

It’s also an age of more unpredictable and ferocious weather patterns. More heat energy in the oceans drives more moisture in the air.

What this means for our coasts is that more are switching from depositional to erosional. And that erosion is increasing. This astounding set of three photos -- reproduced with permission from meteorologist Dave Epstein’s public Twitter feed -- shows what is happening to Plum Island, MA.

My favorite beach, Curtis Cove in Biddeford, wasn’t spared by last week’s storms. The wall of rip-rap (huge granite boulders) protecting the road at the headland has slumped down. The waves pummeled the underlying sand hard, eroding it out from under the wall.

Down at the actual cove, many of the cobbles & pebbles that usually line the backshore were now strewn all over the Timber Point trail head.

Fixing this will be expensive for a city with an already tight budget.

As erosion accelerates the world over, we are left with two stark choices: Spend ever more money on beach replenishment and seawalls, or let the world change.

We don’t like change. When we build our houses and towns on the coast, we want them to stay on the coast. We want our memories to last, and to become our children’s memories, and their children’s.

That has always come with a cost. The cost is now increasing, rapidly.

Plum Island, MA; source

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* If you visit this NOAA site, check out Alaska. You’ll see the relative sea levels there seem to be plummeting. When Alaska and Canada were covered with glaciers, the weight of that ice actually pushed the land downward. Now with the ice melted, the land is rebounding upward faster than the sea is rising. The world is constantly changing!

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About the Author

Visiting a Maine beach in March 2010, Harold Johnson was shocked by the ocean-borne debris left by recent storms. He grabbed a garbage bag and a camera, and hasn’t looked back.

Since then he has spent most of his free time studying marine pollution, coastal ecosystems, and the mysteries and science of ocean and shore.

Copyeditor and writer by trade, historian and archaeologist at heart, Johnson’s philosophy is simple: Dig below the surface, travel the currents, make the connections, learn. Then share what you learn. He lives in Saco with his wife and young daughter. Follow on Twitter @FlotsamDiaries.

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