Cutting Greenhouse Gases: The Role for Farms and Forests

This week's climate fact

Posted: 16-May-2008; Updated: 21-May-2008

Previous Climate Facts described findings from an analysis by the widely-respected consulting firm McKinsey & Company which shows that the U.S. has the technology available today to significantly cut U.S. emissions through 2030¹.

This week we focus on options McKinsey & Co. identified to cut greenhouse gases through expanding and enhancing stored carbon in forests and farmlands.

New carbon sequestration in forests and farms could abate at least 440 million metric tons of CO₂ equivalents (CO2e) annually by 2030, about as much as if the utility sector cut its emissions 16% below projected levels in 2030. McKinsey & Co. did warn, however, that because carbon sinks are so widely dispersed we may fail to capture these reduction opportunities without "strong, coordinated, economy-wide action."

There are several ways to capture opportunities for farms and forests in climate legislation, some of which are included in the Lieberman-Warner Climate Security Bill (S.2191) expected to come to the Senate floor in June.

How can farmers and landowners achieve these cuts? McKinsey & Co. identified five areas of opportunities:

1. Afforestation of degraded or idle pastureland that has low productivity or is vulnerable to erosion - Seven percent of pastureland in the U.S. (seventeen million hectares) is degraded or not used to its full potential. McKinsey & Co. reported that planting trees on this marginal pastureland could store at least 130 million metric tons of carbon each year without significantly affecting livestock production.
2. Improved forest management - Reforestation of low-density areas or recently harvested stands, active management like thinning and stand improvement of private lands, and passive forest management like restricted grazing are simple practices that could greatly reduce greenhouse gases. In aggregate, McKinsey & Co. reports, these practices could store a total of 110 million metric tons of CO2e per year.
3. Planting trees on marginal or unused cropland - Farmers can sequester carbon on unused cropland without decreasing crop production, and could even get paid for it. McKinsey & Co. researchers reported that there are 13 million hectares of marginal cropland that, if planted with trees, could provide additional income for farmers under a climate bill and 80 million metric toms of annual CO2e abatement.
4. Conservation tillage - Conventional tilling prevents carbon from accumulating in the ground. But by adopting conservation practices, like no-till and low-till that significantly reduce the disruption of organic matter in the soil, McKinsey & Co. reports that farmers could store 80 million metric tons of CO2e each year.
5. Winter cover crops - Planting winter crops like grass or legumes on harvested land has several benefits. Winter crops preserve soil and therefore reduce the amount of fertilizer needed in the summer growing season by as much as 30 percent, and reduce erosion and nitrate leaching. McKinsey & Co. reports that winter cover crops could store an additional 40 million metric tons of carbon in the soil each year.

We have the opportunities to substantially increase our national carbon stores, but only if Congress mobilizes farmers and foresters to cut greenhouse gases. It's time to cap emissions.