How to See the Future in a Salt Marsh

How is a salt marsh like a crystal ball? In this case, it's the salt marsh that can predict the future. Scientists at the Smithsonian Environmental Research Center are using an area near Annapolis, MD, to predict how rising carbon dioxide levels in the atmosphere will affect plant life on Earth in the decades to come.

Chief Correspondent Tyler Suiters interviews Biogeochemist Patrick Megonigal, who explains how the experiment works. It's designed to forecast whether the marsh area he's using as a laboratory today will look and behave the same way it does today in 100 years. The marsh ecosystem removes nitrogen and other pollutants from the water, they provide a home for fish and other aquatic life that provide people with food, and they protect human infrastructure from storms. He and his colleagues are trying to determine whether tidal wetlands like this can survive the effects of climate change like rising sea levels.

As the sea levels rise, marshes tend to grow upward, and that's what allows scientists to study how they react to climate change. The wetland ecosystem is also affected by  nitrogen and other pollutants that run off into the water from farm fertilizer and other sources. The levels of those pollutants in the water can affect how the plants react with the CO2. If the pollutant levels are kept low, the increased CO2 levels can actually help the plant life thrive. But too much nitrogen and carbon dioxide doesn't help as much.

The experiment is conducted using transparent "tents," where the CO2 levels are raised to levels predicted by the UN Intergovernmental Panel on Climate Change. Megonigal and his colleague say those are the conditions that will be affecting the marsh by the end of the century. In some chambers, the nitrogen level in the water is also manipulated. Different plants react differently to the higher levels of CO2. There are some benefits, but it's still unclear whether the rising temperatures will have a beneficial effect. The scientists are also trying to determine how the nitrogen levels and the CO2 levels balance against each other.