Carbon Storage in U.S. Eastern Ecosystems Helps Counter Greenhouse Gas Emissions Contributing to Climate Change

WASHINGTON, D.C. – On the one-year anniversary of President Obama’s Climate Action Plan, Secretary of the Interior Sally Jewell today released a new report showing that forests, wetlands and farms in the eastern United States naturally store 300 million tons of carbon a year (1,100 million tons of CO₂ equivalent), which is nearly 15 percent of the greenhouse gas emissions EPA estimates the country emits each year or an amount that exceeds and offsets yearly U.S. car emissions. 

In conjunction with the national assessment, today USGS also released a new web tool, which allows users to see the land and water carbon storage and change in their ecosystems between 2005 and 2050 in the lower 48 states.  This tool was called for in the President’s Climate Action Plan.  

“Today we are taking another step forward in our ongoing effort to bring sound science to bear as we seek to tackle a central challenge of the 21st century – a changing climate,” said Secretary Jewell.  “This landmark study by the U.S. Geological Survey provides yet another reason for being good stewards of our natural landscapes, as ecosystems play a critical role in removing harmful carbon dioxide from the atmosphere that contributes to climate change.” 

With today’s report on the eastern United States, the U.S. Geological Survey (USGS) has completed the national biological carbon assessment for ecosystems in the lower 48 states – a national inventory of the capacity of land-based and aquatic ecosystems to naturally store, or sequester, carbon, which was called for by Congress in 2007. 

Together, the ecosystems across the lower 48 states sequester about 474 million tons of carbon a year (1,738 million tons of CO₂ equivalent), comparable to counter-balancing nearly two years of U.S. car emissions, or more than 20 percent of the greenhouse gas emissions EPA estimates the country emits each year.

The assessment shows that the East stores more carbon than all of the rest of the lower 48 states combined even though it has fewer than 40 percent of the land base.  Under some scenarios, USGS scientists found that the rate of sequestration for the lower 48 states is projected to decline by more than 25 percent by 2050, due to disturbances such as wildfires, urban development and increased demand for timber products.

“What this means for the future is that ecosystems could store less carbon each year,” said USGS Acting Director Suzette Kimball. “Biological sequestration may not be able to offset greenhouse gas emissions nearly as effectively when these ecosystems are impaired.”

Forests accounted for more than 80 percent of the estimated carbon sequestered in the East annually, confirming the critical role of forests highlighted in the Administration’s climate action initiative.

USGS scientists have been building the national assessment since a 2007 congressional mandate in the Energy Independence and Security Act.  The first report, on the Great Plains, was released in 2011, the second report, on the Western United States, was released in 2012.  Reports on Alaska and Hawaii are expected to be completed in 2015.   

Biological carbon storage – also known as carbon sequestration – is the process by which carbon dioxide (CO2) is removed from the atmosphere and stored as carbon in vegetation, soils and sediment.  The USGS inventory estimates the ability of different ecosystems to store carbon now and in the future, providing vital information for land-use and land-management decisions.  Management of carbon stored in our ecosystems and agricultural areas is relevant both for mitigation of climate change and for adaptation to such changes.

The area studied for the eastern U.S. carbon assessment was defined by similarities in ecology and land cover. The study area extends eastward from the western edge of the Great Lakes and the Mississippi floodplains, across the Appalachian Mountains, to the coastal plains of the Atlantic Ocean and the Gulf of Mexico. The major ecosystems USGS researchers evaluated were terrestrial (forests, wetlands, agricultural lands, shrublands and grasslands), and aquatic (rivers, lakes, estuaries and coastal waters).

MAJOR FINDINGS ON BIOLOGICAL CARBON STORAGE

IN THE EASTERN UNITED STATES

 U.S. Geological Survey, June 2014

Major Findings: Current Eastern Carbon Storage (between 2001 and 2005)

●     The eastern U.S., with just under 40 percent of the land in the lower 48 states, stores more carbon than the rest of the conterminous United States.

●     Forests, which occupy about half the land in the East, accounted for more than 80 percent of the region’s estimated carbon sequestered annually. They are the largest carbon-storing pools, and have the highest rate of sequestration of the different ecosystem types.

●     Wetlands, including coastal ones, which comprise only about 9 percent of the land cover in the region studied, account for nearly 13 percent of the region’s estimated annual carbon storage. They also have the second-highest rate of sequestration of all ecosystem types. Nutrients and sediments in rivers and streams flowing from terrestrial environments contribute significantly to the storage of carbon in eastern coastal sediments and deep ocean waters.

●     In contrast, carbon dioxide is emitted from the surface of inland water bodies (rivers, streams, lakes and reservoirs), equal to about 18 percent of the recent annual carbon sequestration rate of terrestrial ecosystems in the East.

●     Agricultural areas cover about 31 percent of the East, and account for only 4 percent of the region’s annually sequestered carbon.  

●     Grasslands and shrublands, as well as other types of land, contained just 1.1 percent or less of the region’s carbon.

Major Findings: Projected Changes in Eastern Carbon by 2050

●     The eastern United States is projected to continue to be a carbon sink (absorbs more carbon than it emits) through 2050, increasing the carbon stored by as much as 37 percent.  However, the rate of sequestration is projected to slow by up to 20 percent, primarily because of decreases in the amount of forest cover.

●     Land use is projected to continue to change in the future; landscape changes are projected to be between 17 and 23 percent by 2050 under different scenarios. These changes, primarily the result of demands for forest products, urban development and agriculture, could affect the future potential storage capacity of the region’s ecosystems and other lands because future carbon stocks are inextricably linked to land-use practices and changes.  

●     The area projected to experience the most change – about 30 percent -- is the southeastern United States, primarily because of conversion of land from forests to agricultural and urban land.

●     By 2050, coastal carbon storage could increase by 18 to 56 percent.  Land-use changes could increase nutrient and sediment flow from urban and agricultural lands (which presents a separate challenge), but this would also increase the amount of carbon stored in coastal areas.                                                                

For more information on the assessment, visit HERE. Watch a short video on the assessment HERE.

Visit the web tool HERE. Watch a tutorial on how to use the web tool HERE.

Read some FAQs on the Eastern Carbon Report