The Mid-Atlantic and Northeast seaboard has been seeing the signs of climate change for decades. Sea levels and sea-surface temperatures have risen throughout the world. In the Mid-Atlantic:
- The average sea-surface temperature on the Northeast Shelf has increased by about 2.3°F since 1854, with about half of this change occurring in the last few decades.
- In particular, the waters of the Gulf of Maine are warming dramatically in recent years– faster than 99 percent of the global ocean between 2004 and 2013.
- Sea levels are also rising more quickly than the global average along many areas of the coastline in our region. Between 1950 and 2009, sea levels rose 3 to 4 times faster than the global average along a “hotspot” of about 1,000 kilometers (621 miles) from Cape Hatteras to Cape Cod. This rise in sea level is due to a combination of water volume expanding as the oceans warm (thermal expansion), melting of glaciers and ice sheets, changes to Atlantic Ocean circulation, and land subsidence.
NOAA Scientists Predictions for the Future:
- New high-resolution climate models indicate Northeast Shelf waters may warm another 5.4°F by the end of the century compared to today’s conditions–nearly three times the global average.
- A NOAA sea level rise study in 2017 found east coast cities like Boston, Massachusetts and Annapolis, Maryland could see ocean levels rise by as much as 11.5 feet higher than today by the end of the century.
As waters warm, fish and invertebrates (like crabs and lobsters), are moving north and into deeper waters to find the cooler waters they prefer. The habitats that these species depend on for food, shelter, and spawning are changing, too.
According to data from the NOAA Fisheries bottom trawl survey on the Northeast Shelf, the average shift in the distribution for all species from 1967-2016 has been almost 8 miles north per decade and almost 8 feet per decade in depth. That changes what fishermen are catching, and changes the ways they fish.
Coastal wetlands provide nursery areas for juvenile fish and provide foraging habitat and shelter from larger predators. At least 50 percent of all commercially important fish and shellfish in the United States depend on estuaries and nearshore coastal waters.
As sea levels rise, coastal salt marshes retreat landward, but when their retreat path is blocked by coastal areas hardened by shoreline structures, such as seawalls or rock revetments, we lose wetlands in what is known as “the coastal squeeze.”
The loss of coastal wetlands from rising sea levels and storms will reduce wetland-dependent fish and invertebrates, and reduce the natural protections to coastal communities. The estimated loss of coastal wetlands due to the combined effects of sea level rise and coastal development, like the construction of seawalls, could be more than 50 percent by the end of the century. One study found nearly 90 percent of brackish, high-marsh wetlands in the Chesapeake Bay would be lost under a 3 foot sea level rise scenario by 2100.
Coastal wetlands buffer coastal communities from the effects of flooding, erosion, and storm surges. Fortunately, there are alternatives to traditional, hardened shoreline development that not only give coastal wetlands a chance to adapt to sea level rise, but also provide functioning habitat for marine and estuarine species. “Living shorelines” can protect and restore shoreline ecosystems through the use of natural materials like plants, oyster shells, sand, and rocks, and sometimes include materials like fiber rolls or anchored wood. These elements don’t interrupt the natural water/land continuum.