The Climate in Emergency

A weekly blog on science, news, and ideas related to climate change

Breaking Barriers

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Cowboys and Indians 3 will post on Monday. In the meantime, here is a re-post from the original blog on the Climate Emergency Institute site.

Global climate change may be too abstract a notion for many people to think clearly about. Information, like pizza, cannot be chewed or digested well if you bite off too big a piece at once. Anything that prevents large numbers of people from thinking clearly and concretely about a problem can effectively block public change.

In the interests of moving through this block, I contacted Bill Hulslander, Chief of Resource Management at Assateague Island National Seashore, and asked him about sea level rise. Using his responses, plus my own familiarity with the island as a former intern there, let us look at climate change in one, particular place.

Assateague Island is part of the barrier island chain protecting much of the Atlantic and Gulf coasts. These islands and peninsulas are essentially very large offshore sand bars with forests, shrub-lands, and marshes growing on them. They protect the mainland from the worst of ocean storms and provide valuable wildlife habitat, unless they are converted to resort towns, as most of them have been.

Assateague is one of the few exceptions. It is not one park but three, with different parts of the island managed by different agencies. Famous for its free-roaming horses, Assateague also supports several endangered or threatened plants and animals. The island is 37 miles long, and varies in width from about two miles on the southern end to a few hundred yards in the north. It straddles the border between Maryland and Virginia. As a low-lying island, Assateague is vulnerable to changes in both sea level and the frequency and intensity of storms. As a tourist destination familiar to millions of people, it is a place where people might see change they can relate to.

Not all change on Assateague is related to sea level rise, and not all sea level rise is related to climate change. For example, the land in this part of the country is subsiding for geologic reasons, so the sea would be gaining on the island anyway. Also, Assateague is made of sand and sand moves easily. Storm waves would constantly reshape the island no matter what.

Mr. Hulslander says that the sea has been rising globally since at least the 1800’s (he does not say whether that rise is due to global warming, but it certainly could be, given that the Industrial Revolution had already begun). That means it is impossible to say what the island would do, how it would move, without sea level rise. There is no baseline data. All this means that it is hard to tell which of Assateague’s changes are natural and which are not. It may be enough to know that Assateague is changing, and that climate change is one of the reasons why.

Assateague moves west as major storms wash sand over the island and into the bay behind it. The process erodes the beach while building up the marshes on the other side of the island. Most visitors don’t notice this movement, because it has not changed the overall character of the land in recent years. Park rangers do notice it. They have had to move or abandon some of their infrastructure on the island. They can easily remember old, historic buildings lost to storms, their former locations now permanently under water.

The rangers tell the story of a man whose family did not sell their land on Assateague to the government when the park was created. He returned years later, curious about his property. The rangers gently explained to him that his land (which he had been paying county taxes on) was now several yards off shore. The rangers helped him sort out his tax problem, and the story is usually told in a light-hearted way, but one can imagine this family’s disappointment and regret.

The Park Service is working to plan for the coming changes to the island’s shape and size, so that their land is not unexpectedly discovered under water, too. As part of this effort, park scientists are carefully mapping the island and studying its relationship to the sea. Again, according to Mr. Hulslander:

A sea-level rise of 3.5 to 9 inches (8 to 22 cm) by 2040 may claim some of the barrier island’s valuable landscape.…The pace of sea-level rise will be the determining factor in the ability of habitats to adapt to new landscapes and environmental conditions.  If the pace is too swift, [and the growth of the marshes cannot keep up] the island may reach a tipping point and become more of a broken chain of low, sandy islands.

The loss of an intact barrier could make the mainland behind more vulnerable to storms, as well as being psychologically difficult for those who love Assateague. Whether or not the island breaks up, many of the natural communities on Assateague may be altered or destroyed due to periodic flooding and changes in groundwater salinity. In the short term, says Mr. Hulslander, some endangered species may find habitat on the island enhanced. Both seabeach amaranth and piping plovers, for example, need the sand flats created when storm waves wash over the island. Higher sea levels, plus an increase in the severity and number of storms caused by warming seas, means that waves will wash across the island more often. More frequent overwash means more habitat for amaranth and plovers, up to a point. Other species with different needs may not fare as well, and storms that are too frequent will wash even the sand-flat dwellers away.

Once upon a time, the loss of individual barrier islands would only have displaced natural coastal communities to other islands, or to the newly exposed mainland. Change is typical for barrier islands, and the number and location of barrier islands has varied historically. Unfortunately, the guiding rationale for the creation of parks is that by dedicating some land to wildlife and nature-based recreation, a portion of these resources will be protected in perpetuity. Meanwhile, surrounding lands are converted to farmland or beach-font resorts, because the need to preserve wild lands has supposedly been taken care of.

The very rapid change Assateague is beginning to undergo is at odds with its designation as anything in perpetuity. The island cannot serve as a refuge if it is flooded.

The Park Service as a whole is making plans based on multiple possible climate change scenarios for the next few decades. These scenarios are based on the various plausible emission rates. The research that will allow the park to develop specific scenarios for its own island has only begun. As Mr. Hulslander points out, these are planning tools, not predictions. If the island does X, the rangers are prepared to do Y. Some, or all, of the infrastructure on the island may be moved to the mainland. Some camping may also be moved to the mainland.

It is sobering to consider that nearby islands, such as Fenwick, are subject to the same pressures from sea level rise and increased storms. Ocean City, Maryland, which sits on Fenwick Island, can hardly be moved to the mainland. The city is fighting the sea by piling the beach with extra sand, for however long they can keep up that expense. The people who live on that island are vulnerable.

It is sobering, too, to consider that Assateague Island National Seashore is only about fifty years old. It is possible that, barring a miracle of public willingness to deal with global warming, some of the people who saw it win Federal protection may live to see the island break.


Author: Caroline Ailanthus

I am a creative science writer. That is, most of my writing is creative rather than technical, but my topic is usually science. I enjoy explaining things and exploring ideas. I have one published novel and another on the way. I have a master's degree in Conservation Biology and I work full-time as a writer.

One thought on “Breaking Barriers

  1. Pingback: Just the Facts | The Climate in Emergency

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