Role of Carbon and Agriculture
in Climate Change
Cropland, pasture/rangeland, and forested lands represent nearly half of the land use in the United States, and agriculture accounts for 10% of U.S. greenhouse gas emissions. The graphic from Sanderman’s Soil Carbon Debt of 12,000 years of Human Land Use describes the global distribution of crop and grazing lands.
Sanderman et al (2017) goes on to explain that human interactions with agricultural land have depleted soil organic carbon stocks. In other terms, the organic carbon that took thousands of years to accumulate in the soil has declined, by "[median value] 26% for the upper 30 cm and 16% for the top 100 cm of soil, but ranges of −36 to 78% and −25 to 61%, respectively, have been reported for these two depth increments " (5).
Human use of landscapes over time has led to depletion of soil carbon.
Much of his carbon that is no longer stored in the soil as organic carbon, one of the three major carbon storage opportunities on working lands, has been returned to the atmosphere, primarily as carbon dioxide.
Check your knowledge!
According to graphs and maps above from Sanderman et al. Soil Carbon Debt of 12,000 years of Human Land Use, as grazing lands and cropland have expanded, the cumulative soil organic carbon has [increased/decreased/no correlation].
Discussion board: If you have any questions throughout Module 1, please use the discussion board to below to post.