Agriculture, Climate Change and Carbon Sequestration A Publication of ATTRA—National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.org By Jeff Schahczenski Carbon sequestration and reductions in greenhouse gas emissions can occur through a variety of and Holly Hill agriculture practices. This publication provides an overview of the relationship between agriculture, NCAT Program climate change and carbon sequestration. It also investigates possible options for farmers and ranchers Specialists to have a positive impact on the changing climate and presents opportunities for becoming involved © 2009 NCAT in the emerging carbon market. Table of Contents Introduction ............................1 Climate change science ......2 How does climate change infl uence agriculture? .........3 How does agriculture infl uence climate change? ....................................3 Agriculture’s role in mitigating climate change ......................................6 The value of soil carbon: Potential benefi ts for agriculture ...............................8 Charge systems: Carbon tax ...............................8 Cap and trade: A private market for greenhouse gas emissions .........................9 Subsidizing positive behavior .................................12 Summary ................................13 References .............................14 Resources ...............................14 Appendix: How to get involved in voluntary private carbon markets ....................15 An organic wheat grass fi eld. Growing research is showing that organic production systems are one of the most climate-friendly systems of food production. Introduction • lengthen the growing season in regions with relatively cool spring The Earth’s average surface temperature and fall seasons; increased 1.3 degrees Fahrenheit over the • adversely affect crops in regions ATTRA—National Sustainable past century, and is projected by the Inter- Agriculture Information Service where summer heat already limits (www.ncat.attra.org) is managed governmental Panel on Climate Change to production; by the National Center for Appro- increase by an additional 3.2 to 7.2 degrees priate Technology (NCAT) and is • increase soil evaporation rates; and funded under a grant from the over the 21st century (IPCC, 2007a). These United States Department of Agriculture’s Rural Business- seemingly slight changes in temperature • increase the chances of severe Cooperative Service. Visit the could have profound implications for farm- droughts (2008a). NCAT Web site (www.ncat.org/ sarc_current.php) for ers and ranchers. According to the Envi- Innovative farming practices such as conser- more information on ronmental Protection Agency, an increase our sustainable agri- vation tillage, organic production, improved culture projects. in average temperature can: cropping systems, land restoration, land use change and irrigation and water manage- habitable. Increased levels of greenhouse ment, are ways that farmers can address gases enhance the naturally occurring climate change. Good management prac- greenhouse effect by trapping even more of tices have multiple benefi ts that may also the sun’s heat, resulting in a global warm- enhance profi tability, improve farm energy ing effect. Figure 1 illustrates the natural effi ciency and boost air and soil quality. and enhanced greenhouse effects (Pew Cen- ter on Global Climate Change, 2008). Climate change science The primary greenhouse gases associated Natural shifts in global temperatures have with agriculture are carbon dioxide (CO2), occurred throughout human history. The methane (CH4) and nitrous oxide (N20). Related ATTRA Although carbon dioxide is the most prev- Publications 20th century, however, has seen a rapid rise in global temperatures. Scientists attribute alent greenhouse gas in the atmosphere, Conservation Tillage the temp increase to a rise in carbon diox- nitrous oxide and methane have longer durations in the atmosphere and absorb Pursuing Conservation ide and other greenhouse gases released Tillage Systems from the burning of fossil fuels, deforesta- more long-wave radiation. Therefore, small for Organic Crop tion, agriculture and other industrial pro- quantities of methane and nitrous oxide can Production cesses. Scientists refer to this phenomenon have signifi cant effects on climate change. as the enhanced greenhouse effect. Energy Saving Tips Several excellent resources and fact sheets for Irrigators The naturally occurring greenhouse effect explain the greenhouse effect and the Anaerobic Digestion traps the heat of the sun before it can science behind climate change. See the of Animal Wastes: be released back into space. This allows Resources section for information on how Factors to Consider the Earth’s surface to remain warm and to obtain copies. Biodiesel: The Sustainability Dimensions Figure 1. The Greenhouse Eff ect Source: The National Academy of Sciences. www.climatechange.ca.gov/publications/faqs.html Ethanol Opportunities and Questions Natural Greenhouse Eff ect Enhanced Greenhouse Eff ect The greenhouse eff ect is a natural warm- Increasing the amount of greenhouse gases Renewable Energy ing process. Carbon dioxide (CO2) and cer- intensifi es the greenhouse eff ect. This side Opportunities on tain other gases are always present in the of the globe simulates conditions today, the Farm atmosphere. These gases create a warm- roughly two centuries after the Industrial Federal Resources for ing eff ect that has some similarity to the Revolution began. Sustainable Farming warming inside a greenhouse, hence the and Ranching name “greenhouse eff ect.” Illustration of the greenhouse eff ect (courtesy of the Marion Koshland Science Museum of the National Academy of Sciences). Visible sunlight passes through the atmosphere without being absorbed. Some of the sunlight striking the earth (1) is absorbed and converted to heat, which warms the surface. The surface (2) emits infrared radiation to the atmosphere, where some of it (3) is absorbed by greenhouse gases and (4) re-emitted toward the surface; some of the heat is not trapped by greenhouse gases and (5) escapes into space. Human activities that emit additional green- house gases to the atmosphere (6) increase the amount of infrared radiation that gets absorbed before escaping into space, thus enhancing the greenhouse eff ect and amplifying the warming of the earth. Page 2 ATTRA Agriculture, Climate Change and Carbon Sequestration How does climate change will likely extend forage production infl uence agriculture? into late fall and early spring. • Climate change-induced shifts in Climate change may have benefi cial as well plant species are already under way as detrimental consequences for agricul- in rangelands. The establishment ture. Some research indicates that warmer of perennial herbaceous species is temperatures lengthen growing seasons and reducing soil water availability early increased carbon dioxide in the air results in the growing season. in higher yields from some crops. A warm- ing climate and decreasing soil moisture can • Higher temperatures will very likely also result in production patterns shifting reduce livestock production during northward and an increasing need for irri- the summer season, but these losses gation. Changes, however, will likely vary will be partially offset by warmer signifi cantly by region. Geography will play temperatures during the winter a large role in how agriculture might benefi t season (Backlund et al., 2008). from climate change. While projections look favorable for some areas, the potential of How does agriculture increased climate variability and extremes infl uence climate change? onserva- are not necessarily considered. Benefi ts to tion tillage, agriculture might be offset by an increased Agriculture’s contribution to likelihood of heat waves, drought, severe Corganic thunderstorms and tornadoes. An increase greenhouse gas emissions production, cover in climate variability makes adaptation dif- Agriculture activities serve as both sources cropping and crop fi cult for farmers. and sinks for greenhouse gases. Agriculture rotations can dras- sinks of greenhouse gases are reservoirs of tically increase the The U.S. Department of Agriculture carbon that have been removed from the released a report in May 2008 that focused atmosphere through the process of biologi- amount of carbon on the effects of climate on agriculture, cal carbon sequestration. stored in soils. specifi cally on cropping systems, pasture and grazing lands and animal management The primary sources of greenhouse gases in (Backlund et al., 2008). The following fi nd- agriculture are the production of nitrogen- ings are excerpted from the report: based fertilizers; the combustion of fossil fuels such as coal, gasoline, diesel fuel and natural • With increased carbon dioxide and gas; and waste management. Livestock enteric higher temperatures, the life cycle fermentation, or the fermentation that takes of grain and oilseed crops will likely place in the digestive systems of ruminant progress more rapidly. animals, results in methane emissions. • The marketable yield of many hor- Carbon dioxide is removed from the atmo- ticultural crops, such as tomatoes, sphere and converted to organic carbon onions and fruits, is very likely to through the process of photosynthesis. As be more sensitive to climate change organic carbon decomposes, it is converted than grain and oilseed crops. back to carbon dioxide through the process • Climate change is likely to