Though best known for her enduring book, Silent Spring (1962), Rachel Carson was most interested in the sea, especially the realms where land and water meet, whether a rocky shoreline on the Maine coast, a fringing coral reef along the Florida Keys, or the shifting ribbons of sandy barrier island beaches that meander along portions of the Atlantic Coastal Plain including southeast North Carolina where the Northeast New Hanover Conservancy is stewarding some of this region’s last best examples of its natural heritage and associated biodiversity.
In her first book, The Edge of the Sea (1955), Rachel Carson captured the most important facts we need to understand about the interface where land and water meet: “For no two successive days is the shore line precisely the same. Not only do the tides advance and retreat in their eternal rhythms, but the level of the sea itself is never at rest. It rises and falls as the glaciers melt or grow, as the floor of the deep ocean basins shifts under the increasing load of sediments, or as the earth’s crust along the continent margin warps up or down in adjustment to strain and tension.”
The take-away in her concise wording is the fact that today’s coast is not the same as yesterday’s and it won’t be the same tomorrow, for irrefutable reasons tied to a currently expanding ocean—used here in the singular because there is only one ocean on Earth—rightly called the Great Ocean; a body of water so vast that mapmakers, centuries ago, were compelled to delineate and name its body in sections including, but not limited to, the Atlantic, Pacific, Indian, Arctic, and Southern Oceans, each vast in their own right, and each further divided into smaller seas including the Red, Caribbean, Mediterranean, and more than 70 others.
In southeast North Carolina, the land/ocean interface includes a broken line of barrier islands built of sand that originated in the now much weathered Appalachian Mountains and carried here by wind and water that has swept the coastal plain landscape for millions of years. But that’s not to say our current coast is that old. It’s pretty young, geologically-speaking, and it’s not in the same place as it was just a few decades ago because of physical laws pertaining to what happens when water warms: it expands.
The term “sea level rise” is, in my opinion, less relevant than consequential ocean expansion that’s resulting from the addition of water from melting glaciers, compounded by overall ocean warming—that Dr. Carson alluded to in the above quote. Think millimeters of water spilled on a kitchen counter. As with our relatively level coastal plain, those millimeters of water spread out and, in this region, that results in saltwater intrusion, coastal drowning, and habitat shifting, as once forested land adapted to fresh water succumbs to salty water. But nature abhors a vacuum and where once there was forest and freshwater rivers, we now see salty marshes and tidal creeks.
As Earth’s climate transitioned between periods of global warming and global cooling during the past millions of years, the interplay of these two conditions, melting glaciers and warming ocean water, so-called feedback loops, have shaped and reshaped the world’s coastal realms many times over. It’s deep time history and we can read about it in the rocks, sands, and fossils that our changing Earth leaves behind. Actually, we can see more recent evidence of our changing coastline by observing the stark skeletons and stumps of dead trees standing in the salty interface of land and ocean all along the NC coastal plain. These are the sentinels telling us change is afoot—change we ignore to our peril.
To be clear, our species, Homo sapiens, is not the cause of climate change. We are the change agents for the rate of climate change. This is an important distinction to understand. Climate change has existed since Earth developed its first atmosphere, but that change has always been slow, save for a period following the catastrophic collision between Earth and an asteroid that eliminated dinosaurs. That was kind of a one-off event. What’s most climatologically relevant, as regards our children’s future, is the hastening rate of climate change toward warming. We know this is true based on nearly 200 years of ocean temperature data collected by ship captains going back to the development of thermometers.
Ocean researchers in Dr. Carson’s era knew about climate change but they were only beginning to ponder human influence on its rate of change, which was slower just 70 years ago, but is now speeding up due to the indisputable greenhouse effect. What alarms biologists, including me, is knowing the pace of global change has not occurred this quickly in the history of our species and that of all the plants and animals with whom we share this planet. This is important because all species require time to adapt to change, even if it changes at glacial speed.
In college, half a century ago, we talked about humans being good at responding to sudden crises such as storms and earthquakes. For a variety of reasons not worth exploring here, history proves we aren’t so good at responding to relatively slow, gradual change, such as we are experiencing with today’s climate. And this does not bode well for today’s children.
That said, we know for a fact that the Great Ocean was warmer in 1950 than in 1900. We also know the ocean is warmer today than it was in 1970. But the head-scratching part of all this comes when pondering deeper time than 50 or 100 years. If we look back at the history of this area when Earth was locked in a period we call the Glacial Maximum, we can see in the geologic and fossil records that the land/water interface just twenty thousand years before present was located some 50-plus miles east of our present-day beaches.
As Dr. Carson points out, the Great Ocean “rises and falls as the glaciers melt or grow.” During periods of glacial maximums, ice sheets miles thick and composed of fresh water evaporated from the ocean, are deposited in northern and southern latitudes as snow and ice that accumulate into ice sheets until Earth’s climate cycle switches to warming, most recently about ten thousand years before present, as it has done many times before—albeit more slowly than present day. The timing of Earth’s climate cycles is tied to shifts in our planet’s tilt—its angle relative to the sun. But I digress.
Closer to the present day, during the Civil War, less than 200 years ago, some of our beaches were located half a mile and more offshore of familiar places like Wrightsville Beach. The so-called “Graveyard of the Atlantic” is where Confederate and Union ships ran aground and sank in shallow water, where now they are covered by 30 and more feet of ocean water. Yes, the ocean is rising but it’s also expanding, and these two facts are relevant to coastal residents because the land we have today is more than we will have tomorrow. And this statement is made to underscore the importance of protecting whatever remaining land we have, for the benefit of today’s children.
This note began as a narration about the natural wonders to be found in a saltmarsh. But as I typed some words about the charming diamondback terrapin, a small turtle adapted to life in the salty interface where land and saltwater meet, I recalled something I learned from Rachel Carson, who said, “To understand the shore, it is not enough to catalogue its life. Understanding comes only when, standing on a beach, we can sense the long rhythms of earth and sea that sculpted its landforms and produced the rock and sand of which it is composed.”
And this brings me back to the Northeast New Hanover Conservancy, one of the smallest land trusts in NC but the steward of some of the rarest habitats to be found anywhere in the world. In all, NENHC oversees close to 2,000 acres of New Hanover County’s roughly 127,000-acre area, including forested freshwater wetlands and grassy saltmarshes—transitional habitats that connect drier uplands to wetter lowlands.
Regarding the latter, NENHC stewards an 88-acre saltmarsh habitat behind the north end of Wrightsville Beach, and an approximately 800-acre tract of saltmarsh located behind the north end of Figure Eight Island. Most of our work in these marshes involves site visits to monitor impacts of human activities in tidal creeks and adjacent “haul-out areas” that are important forage and nesting habitat for marsh-dwelling birds and the imperiled Diamondback Terrapin.
This is the guiding principle that directs the Northeast New Hanover Conservancy’s works. Yes, NENHC is a small land trust. It’s also nimble and locally focused on working for the public good. For the good of future generations, we may never know.
Andy Wood is a conservation biologist helping monitor, manage, and protect the land and water resources under NENHC’s care. In his spare time Andy directs the activities of www.CoastalPlainConservationGroup.org.