Forests, grasslands and shrublands in the West sequester nearly 100 million tons of carbon each year, an amount equivalent to counterbalancing the emissions of about 83 million passenger cars a year in the United States, according to a new USGS report.
Carbon that is absorbed or “sequestered” through natural processes reduces the amount of carbon dioxide in the atmosphere.
While the study showed that western ecosystems are a strong carbon sink now, the region could experience a decline in storage potential between now and 2050, depending on future changes in land-use, climate and wildfires. Future carbon stocks are inextricably linked to these drivers because as ecosystems, forests or agricultural lands are converted for other uses, their ability to capture and store carbon is affected.
From the Rocky Mountains to the Pacific Coastal Waters
The area USGS studied extends from the Rocky Mountains to the Pacific coastal waters, and totals just over 1 million square miles. The major ecosystems evaluated were terrestrial — forests, wetlands, agricultural lands, and shrublands and grasslands — and aquatic — rivers, lakes, estuaries and coastal waters. It includes well-known ecosystems, such as the Rocky Mountains and the Sierra Nevada Mountains, the Mojave and Sonoran deserts, the Pacific Northwest forests and the vast grasslands and shrublands of the Great Basin.
Western Forests Stored the Most Carbon
While the western ecosystems varied widely in their potential for storing carbon now and in the future, forests are by far the largest carbon-storing pools, accounting for about 70 percent of the carbon stored recently in the West.
Significant Greenhouse Gas Emission Sources in Western Ecosystems
Wildland fires in western ecosystems generated significant amounts of greenhouse gas emissions, with such emissions equivalent to 13 percent of the estimated rate of the recent annual carbon sequestration by western terrestrial ecosystems. This amount could increase up to 31 percent in the future.
Water bodies in the West emitted even more CO2 than fires. Emissions from water bodies are equivalent to more than 30 percent of the recent annual carbon sequestration rate of terrestrial ecosystems in the West. Basically, the more interaction with the atmosphere, the more CO2 is released. So, in fast-moving waters, where the water is churned up, there is a greater loss of CO2 to the atmosphere.
Land-Use, Land-Cover, and Carbon Stocks
Future changes in the ability of western ecosystems to sequester carbon will depend on future changes in land-use, climate, and wildfires. Future carbon stocks are tied to these drivers because as ecosystems, forests or agricultural lands are converted for other uses, their ability to capture and store carbon is affected. Land use by people causes a significant loss of carbon from ecosystems. Specific examples are forest harvesting (nearly 13 million tons of carbon per year) and agricultural harvesting (more than 20 million tons of carbon per year).
To Read More:
Blog on the Report by David Hayes, Deputy Secretary of the Department of the Interior
Department of the Interior News Release on the New Report