Islands that can change shape and move naturally?
Unlike islands made of rock, barrier islands made of sand constantly shift and reshape themselves. Each wave or gust of wind alters these shores. Season by season, the island moves gradually westward and grows southward. Sometimes, storms change the landscape of Assateague Island overnight. But the hardy plants and animals of the island have adapted to survive and while these natural forces bring challenges for some, they also create new habitat for others.

Click your mouse on each of the three photos below to see animations of the natural processes of geomorphology that change and move Assateague Island.

Listen to Dave Wilson, Executive Director of the Maryland Coastal Bays Program. He compares the natural rollover of barrier islands such as Assateague Island to barrier islands such as Ocean City on Fenwick Island that is prevented from rolling over.

Barrier islands and climate change
Climate change is happening and human activities are contributing to and accelerating this change. While some effects are known and are already visible on the landscape, many are just beginning to be understood. But as the atmosphere warms as it is predicted, sea level will rise and low barrier islands will be especially vulnerable. For this reason, the National Park Service has decided to consider climate change and sea-level rise as key factors influencing the future of Assateague Island.  

What causes the sea level to rise?
The amount of water on Earth is fixed. That is, no more water is added or subtracted from our planet—it is simply moved around or circulated between the water bodies, atmosphere, and land. It can be in liquid form (ocean, rivers, lakes, groundwater), gas form (steam, humidity, clouds), or solid form (land ice, sea ice). Water that is frozen as ice is found either floating on the sea (polar ice shelves, icebergs) or sitting on land (polar ice sheets, mountain glaciers).

Sea level can rise in the ocean primarily due to: 1) the thermal expansion of the ocean, and 2) the melting of land ice.

Water expands when heated.

How will barrier islands be affected by sea-level rise?
Many barrier islands, such as Assateague Island, are relatively flat and low in elevation and so are susceptible to even small changes in water level. Ocean storms often wash waves high up the beach. This storm-related push of saltwater and sand onshore, and sometimes even reaching inland, is called storm surge.

When sea-level rise combines with especially strong storms, the island experiences a much higher storm surge, increasing the effects of flooding and erosion, the formation of inlets, and even the speeding up of barrier island rollover.

Below ground, changes could occur as well

This process of saltwater intrusion can make the ponds too salty for some plants and animals to use.