United States Environmental Protection Agency Office of Policy, Planning, and Evaluation EPA230-F-92-009 May 1992 oEFA Climate Change Discussion Series Forests occupy one-third of the land area of the United States. Trees pro- vide wood products, improve air and water quality, provide wildlife habi- tat, and, through photosynthesis, re- move carbon dioxide (C02) from the atmosphere. Human alterations of for- est ecosystems now account for C02 emissions equal to about 10 to 30 per- cent of total global emissions from hu- man activities (anthropogenic emis- sions). Carbon stored in vegetation and soils is released by clearing, fire, or de- cay. The deforestation of Europe and North America in the past contributed to current global C02 levels. Now defor- Forestry estation of 17 million hectares of tropi- cal forests each year—an area larger than Austria or Tennessee—is eroding the planefs photosynthetic base and adding roughly 1 to 2 billion tons of carbon (in the form of C02) to the atmosphere annually. Limiting for- est loss and planting new trees are immediately available, proven tech- nologies, as well as potentially cost- effective means of reducing the build- up of C02 in the atmosphere. Also, tree growth reduces erosion, improves water quality (decreases pesticide and herbicide use on cropland) provides alternative uses for marginal croplands, increases timber supply, and creates potential wildlife habitat. A1990 study by the Intergovernmental Panel on Climate Change, involving several hun- dred scientists, concluded that a dou- bling of C02 in the atmosphere would most likely lead to a warming of 3" to 8°F (1.5° to 4.5°C) by the end of the century. This warming and resulting shifts in precipitation could have a substantial impact on the quality of forest ecosystems. In addition to tem- perature and precipitation changes, forests are sensitive to other factors (e.g., pests, fire, C02 levels), influ- enced by potential of climate change. Reducing "Greenhouse Gas" Emissions Increasing tree planting in community areas Every tree planted in an ur- ban area not only takes up C02, but it also shades build- ings and pavement in hot weather and shields build- ings from winds in cold weather. Thus, the trees re- duce energy needed for air conditioning and heating and thereby reduce associ- ated C02 emissions. Three well-placed trees around a house can cut home air-con- ditioning energy needs by 10 to 50 percent. Increasing tree planting on privately owned lands and improving management of private non-industrial forest lands Private forest lands—excluding land in industrial ownership)—accounts for 57 percent of all U.S. forest lands. Many crop and pasture lands, highly erodible and marginally productive, are suitable for tree planting. The America the Beautiful Program, if fully implemented, would plant one billion trees per year on private lands for 20 years to achieve a few percent offset The Benefits of Trees LIAVtS. TWIGS BRANCHES: absorb sound and block aioiion- BRAMCHES, i£AVE& provide ana reduce wind EVAPOTMNSPiRA770* from leaves cools surrounding air. LEAVES: filter dangerous pollutants from the air. prevent erosion. in U.S. fossil fuel emissions. This plant- ing program will also be a component of the U.S. Action Plan to mitigate greenhouse gas emissions. International Reforestation Millions of hectares of degraded land are potentially available for reforesta- tion, especially in the tropics. Al- though over one hundred million hect- ares would have to-be planted to off- set 10 percent of the world's current annual fossil fuel emission, preliminary esti- mates suggest that the cost of absorbed carbon could be competitive with other op- tions. If planting schemes can be designed to meet the need for forest products and offset deforestation pressure on primary forests, they will have an added carbon ben- efit. Furthermore, a refores- tation strategy could offer a stream of valuable ecological and economic benefits in ad- dition to reducing C02 con- centrations, such as produc- tion of forest products, main- tenance of biodiversity, wa- tershed protection, non- point pollution reduction, and recre- ation. Increasing paper recycling By lowering demand for new pa- per, recycling could decrease en- ergy related greenhouse gas emis- sions from paper production and re- duce greenhouse gas emissions by slowing forest harvesting. NOTE: Climate change refers to potential modification of the earth's climate resulting from increasing atmospheric concentrations of greenhouse gases such as carbon dioxide (C02), methane (CH<), nitrous oxide (N20), and chlorofluorocarbons (CFCs). Through a naturally occurring process known as the "greenhouse effect," these gases act lo warm the earth by trapping heat in the atmosphere. This process plays an important role in maintaining the earth's current temperature and climate. By increasing concentrations of greenhouse gases, human activities are trapping more heat in the atmosphere and potentially changing the earth's climate. Printed on Recycled Paper ------- Potential Impacts Changes in the range, productivity, and species composition of forests Future climates may no longer support the current mix of species found in different regions of the United States. Forests may experience northward shifts in ranges of species, as well as dieback of species along the south- ern reaches as a result of higher temperatures, drier soils, and other climatic changes or shifts in the cli- matic belts of temperature and precipitation. Changes may begin soon A faster rate of mortality among mature trees, a de- cline in seedlings, and a decline in growth of new spe- cies may be visible in a few decades. Climate change alters factors affecting forest health Drier soils could lead to more frequent fires. Wanner climates may cause the range of forest pests and diseases to expand. Climate change could also exacerbate stress on for- ests caused by air pollution and continued depletion of stratospheric ozone. Higher C02 concentrations can increase growth and reduce water demand. The combined effect of this with higher temperatures is uncertain. The response of forests to climate change will not only affect timber supplies, but will also affect biodiver- sity, runoff, recreational opportuni- ties, and the climate through feed- back scenarios. Anticipatory actions are necessary to prepare for the po- tential impacts of climate change. Today's forest management deci- sions will determine the location and composition of forests during the next century when changes in climate are likely. Potential adaptive re- sponses include: Maintaining forest diversity and extent Potential mechanisms for maintain- ing large and diverse forests include strengthening and enlarging pro- Adaptation tected natural areas and creating con- servation corridors (migratory path- ways) between protected areas to ac- commodate range shifts. Maintain- ing diversity and extensiveness should improve the resilience of forests by in- creasing their ability to adapt to a wide range of climate changes. Modifying harvesting practices and for- est and pest control programs Harvesting practices that preserve existing forest diversity, increase species and age class diversity and allow for rapid removal of dead or dying trees, especially along south- ern and lower-elevation boundaries, could increase diversity and resil- ience of forests. Changes in current programs for fire and pest monitoring and control may be warranted in response to new and more severe threats. Developing and planting heat-, dmugfa-, pest-resistant, fast-growing species and varieties Planting heat-, drought-, and pest- resistant varieties in areas vulnerable to dieback could also increase resil- ience to climate change. In recent years, some companies began plant- ing such species on some of their lands. Faster-growing trees would enhance the ability of foresters to shorten rotation times in response to rapid changes in the climate. Based upon the two EPA Reports to Congress, The Potential Effects of Global Climate Change On The United States, Washington, DC, 1989; and Policy Options for Stabilizing Global Climate., Washington, DC, 1989; and EPA's Adapting to Climate Change: What Govern- ments Can Do, Washington, DC, 1991; and World Resources 1990-91 by World Resources Institute, Washington, DC, 1991 EPA's Climate Change Outreach Program is designed to raise awareness about climate change and provide assistance to state and local governments, industry, and non-governmental organizations in the evaluation of cost-effective response strategies. For further information about this program, please contact Joel Smith at 202/260-8825. U.S. EPA Climate Change Discussion Series 1992 Global Climate Change Sea Level Rise Adaptation to Transportation Climate Change Energy Forestry Water Resources Agriculture Biodiversity Order from: CLIMATE CHANGE INFORMATION US. EPA Office of Policy Analysis Climate Change Division (PM221) 401 M Street, SW. Washington, DC 20460 USA o^6DSr-% i \ I mi ------- |