Calculating Carbon Drawdown by Trees

Adapted from: McPherson, E.G.; J.R. Simpson,; P.J. Peper; and E. Aguaron. 2008. Urban Forestry and Climate Change. Albany, CA: USDA Forest Service, Pacific Southwest Research Station. Available at:

The Center for Urban Forest Research (CUFR) provides a tool for assessing the greenhouse gas drawdown in urban forests, the CUFR Tree Carbon Calculator (CTCC). It is the only tool approved by the Climate Action Reserve’s Urban Forest Project Protocol for quantifying carbon dioxide sequestration from greenhouse gas tree-planting projects.

The calculator tool can be used to estimate greenhouse gas benefits for existing trees or to forecast future benefits for planting projects. The calculator tool is programmed in a Microsoft Office Excel spreadsheet and provides carbon-related information for a single tree located in one of 16 U.S. climate zones.

Once the user enters information about the climate region and tree’s size or age, the calculator produces estimates regarding:

  • carbon dioxide stored in the tree due to its growth over many years,
  • carbon dioxide sequestered during the past year, and
  • dry weight of aboveground biomass that could be utilized if the tree was removed.

If trees are strategically located to shade buildings and to reduce energy consumed for heating and cooling, additional inputs are required. In these cases, the calculator’s outputs include:

  • annual energy savings in kilowatts of electricity and millions of Btu of heating per tree, and
  • carbon dioxide equivalents of these energy savings.

Tree size and growth data were developed from samples of 650 to 1,000 street trees representing approximately 20 predominant species in each of the 16 regional reference cities. Biomass equations, many of them derived from volumetric measurements of open-grown city trees, are used to derive the total amount of carbon dioxide stored and sequestered.

To determine the effects of tree shade on a building’s energy performance, more than 12,000 simulations were conducted for each reference city using different combinations of tree sizes, locations, and building vintages.

Users should recognize that conditions vary within regions, and data from the calculator may not accurately reflect the actual rate of tree growth, microclimate, or building characteristics of the tree in question. When conditions are different, it may be necessary to apply biomass equations manually using adjusted tree growth data and perform building energy simulations with modified weather and tree data to more accurately depict the effects of trees on greenhouse gases levels.

The CUFR Tree Carbon Calculator is intended as “proof of concept” software that is in the testing phase. It is provided “as is” without warranty of any kind. In 2011, this version will be replaced by an Internet-based version with greater functionality.

Adapted by: Tom DeGomez

External Links
Center for Urban Forests Research Tree Carbon Calculator

Related to Calculating Carbon Drawdown by Trees: