US urban trees store carbon, provide billions in economic value

Forest Service research shows that urban trees store an estimated 21
million tons of carbon, which translates to an environmental service
valued at $1.5 billion in economic benefit.

Annual net carbon uptake by these trees is estimated at 21 million tons and $1.5 billion in economic benefit.

In the study published recently in the journal Environmental Pollution, Dave Nowak, a research forester with the U.S. Forest Service’s Northern Research Station, and his colleagues used urban tree field data from 28 cities and six states and national tree cover data to estimate total carbon storage in the nation’s urban areas.

“With expanding urbanization, city trees and forests are becoming increasingly important to sustain the health and well-being of our environment and our communities,” said U.S. Forest Service Chief Tom Tidwell. “Carbon storage is just one of the many benefits provided by the hardest working trees in America. I hope this study will encourage people to look at their neighborhood trees a little differently, and start thinking about ways they can help care for their own urban forests.”

Tens of thousands of people volunteered to plant and care for trees for Earth Day and Arbor Day this year, but there are opportunities all year long. To learn about volunteer opportunities near your home, visit the Arbor Day Foundation.

The Forest Service partners with organizations like the Arbor Day Foundation and participates in programs like Tree City USA to recognize and inspire cities in their efforts to improve their urban forests. Additionally the Forest Service is active in more than 7,000 communities across the U.S., helping them to better plan and manage their urban forests.

Nationally, carbon storage by trees in forestlands was estimated at 22.3 billion tons in a 2008 Forest Service study; additional carbon storage by urban trees bumps that to an estimated 22.7 billion tons.

Carbon storage and sequestration rates vary among states based on the amount of urban tree cover and growing conditions. States in forested regions typically have the highest percentage of urban tree cover. States with the greatest amount of carbon stored by trees in urban areas are Texas (49.8 million tons), Florida (47.3 million tons), Georgia (42.4 million tons), Massachusetts (39.6 million tons) and North Carolina (37.5 million tons).

The total amount of carbon stored and sequestered in urban areas could increase in the future as urban land expands. Urban areas in the continental U.S. increased from 2.5 percent of land area in 1990 to 3.1 percent in 2000, an increase equivalent to the area of Vermont and New Hampshire combined. If that growth pattern continues, U.S. urban land could expand by an area greater than the state of Montana by 2050.

The study is not the first to estimate carbon storage and sequestration by U.S. urban forests, however it provides more refined statistical analyses for national carbon estimates that can be used to assess the actual and potential role of urban forests in reducing atmospheric carbon dioxide.

More urbanization does not necessarily translate to more urban trees. Last year, Nowak and Eric Greenfield, a forester with the Northern Research Station and another study co-author, found that urban tree cover is declining nationwide at a rate of about 20,000 acres per year, or 4 million trees per year.

Carbon Storage by Urban Trees

State / Carbon Stored (tons)

Texas 49,800,000
Florida 47,300,000
Georgia 42,400,000
Massachusetts 39,600,000
North Carolina 37,500,000
New York 35,400,000
California 34,600,000
Pennsylvania 31,700,000
New Jersey 30,900,000
Connecticut 25,700,000
Ohio 25,300,000
Michigan 25,200,000
Tennessee 20,800,000
Alabama 20,600,000
Illinois 20,600,000
South Carolina 19,100,000
Virginia 18,300,000
Washington 15,200,000
Maryland 13,100,000
Missouri 12,400,000
Louisiana 11,600,000
Indiana 10,700,000
Wisconsin 10,400,000
Minnesota 10,200,000
Oregon 8,900,000
Arkansas 8,500,000
Mississippi 8,200,000
New Hampshire 7,900,000
Kentucky 7,100,000
Arizona 6,000,000
West Virginia 5,700,000
Kansas 5,300,000
Colorado 4,800,000
Oklahoma 4,800,000
Rhode Island 4,600,000
Maine 4,200,000
Iowa 4,100,000
Delaware 2,500,000
Hawaii 2,400,000
Utah 2,300,000
Alaska 2,200,000
New Mexico 2,000,000
Nebraska 1,800,000
Vermont 1,700,000
Nevada 1,400,000
Idaho 1,200,000
South Dakota 800,000
Montana 500,000
North Dakota 500,000
Wyoming 300,000
Total 708,100,000

The mission of the U.S. Forest Service is to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. The agency has either a direct or indirect role in stewardship of about 80 percent of our nation’s forests; 850 million acres including 100 million acres of urban forests where most Americans live. The mission of the Forest Service’s Northern Research Station is to improve people’s lives and help sustain the natural resources in the Northeast and Midwest through leading-edge science and effective information delivery.

USDA has made a concerted effort to deliver results for the American people, even as USDA implements sequestration – the across-the-board budget reductions mandated under terms of the Budget Control Act. USDA has already undertaken historic efforts since 2009 to save more than $828 million in taxpayer funds through targeted, common-sense budget reductions. These reductions have put USDA in a better position to carry out its mission, while implementing sequester budget reductions in a fair manner that causes as little disruption as possible.