The Globe spent several months this summer criss-crossing Cape Cod to learn how the effects of climate change are being felt, and what it would mean for the future of the area. In short, we found that climate change is already threatening the Cape in tangible ways, accelerating natural processes like erosion and sea level rise. Read “At the edge of a warming world” for the full story.
Here are some of the most striking things we learned.
1. The Outer Cape now loses about 3 feet of beach a year on average — a rate nearly double what it had been for thousands of years, thanks in part to the continued submergence of Georges Bank off the southeast coast. In other parts of the Cape, the threats are not just the sea level rise, storm activity, and increased rates of erosion amplified by climate change, but the human reaction to these changes. Stone sea walls or rocky protrusions jutting into the ocean help to preserve one piece of property by collecting eroding sand. But each one also prevents that sand from traveling to the beach downstream. The solution in one place exacerbates the problem in another.
2. A spigot of melting ice is pouring fresh water into the North Atlantic Ocean, fundamentally altering the currents that were the basis for the Gulf of Maine’s iconic cold water species. The basin whose southern boundary is marked by the Cape is now warming faster than 99 percent of the world’s oceans. The effects within food chains and delicate ecosystems are enduring and destructive, their tentacles touching lives and livelihoods on land.
3. Wild shellfish populations are at 1 percent of historic levels along the Cape, and commercial farms are struggling to contend with dramatic temperature swings. Raw oysters are one of the few traditional Cape Cod delicacies that are still almost exclusively locally sourced. But climate change is threatening to send them the way of the cod.
4. The population of migratory land birds near the Cape has dwindled to half what it was 50 years ago. Birds — thought of by many researchers as ambassadors of environmental health — have been affected by a multitude of changes, including shifting seasons and disruptions of ecosystems along their migratory paths. “There comes a point at which you have a complete ecological mismatch,” said Trevor Lloyd-Evans, director of Manomet’s land-bird conservation program. Birds arrive at times when the insects they eat are in short supply; birds breed too late and can’t find food for their young.
5. Salt marshes provide a powerful defense against climate change, but sea level rise and other factors are eating away at them. Many of the sport fish we catch and eat spend their early lives here, and marshes filter pollutants that would otherwise seep into the sea. They serve as a buffer when storms roll in, protecting homes built along the uplands. And they are a remarkably effective check on the forces driving climate change, trapping carbon that would otherwise enter the atmosphere 55 times more efficiently than tropical rainforest.
6. Nor’easters are causing uncommon chaos on the Cape, and hurricanes that have hit the Cape in the distant past would today be catastrophic. In 1938, a hurricane put much of the western edge of the Cape under several feet of water and killed 564 people. The sea level has risen a foot since then, the population has quintupled, and many new buildings have been erected in harm’s way.
7. Massachusetts and the Cape have done more than almost anywhere else to prepare for the coastal effects of climate change, but some experts say it is only the beginning of what is needed. Homeowners on the Cape are being faced with rising flood insurance rates and the possibility of having to relocate and elevate their houses. Local governments are just beginning to have hard conversations about what can be preserved and what might wash away.
Cape Cod’s unique geographic perch and geologic makeup leave it particularly vulnerable to climate change. But the effects already on display here are just the beginning. People like to say that the only constant on the Cape is change. But unless the world takes drastic action to reverse the planet’s warming, change will give way to loss.