The joint consideration of agricultural mitigation and adaptation is needed for several reasons. Our research shows that the soil carbon sequestration potential of agricultural soils varies under changing climate conditions (Figure 10.11). Thus, a changing climate clearly will affect the mitigation potential of agricultural practices. If changing climate is not taken into consideration, calculations such as those pertaining to carbon to be sequestered may be in serious error.
On the other hand, mitigation practices can also affect the adaptation potential of agricultural systems. For example, by enhancing the ability of soils to hold moisture, carbon sequestration in agricultural soils helps crops withstand
North Platte, NE
□ Current climate
□ Climate change, CCCM
Figure 10.11 Change in soil carbon in corn production under nitrogen fertilization and irrigation under current climate and under the Canadian Climate Centre and Hadley Center climate change scenarios (From Rosenzweig, C. and F. Tubiello. 2005. Accepted. Mitigation and adaptation in agriculture: an interactive approach. Mitigation and Adaptation Strategies for Global Change. With permission.)
droughts and/or floods, both of which are projected to increase in frequency and severity in a warmer climate. Additionally, sequestering carbon in soil supports larger and more diverse populations of microbes and other organisms that provide services to plants and indirectly to animals, such as producing root growth-promoting hormones. All these functions can contribute substantially to the sustainability of agricultural systems. Adaptation practices may in turn affect the mitigation potential. For example, irrigation and nitrogen fertilization may greatly enhance the ability of soils in semi-arid regions to sequester carbon.
Finally, since it is likely that efforts to reduce the enhanced greenhouse effect (such as the Kyoto Protocol) will not be completely effective, farmers and others in the agricultural sector will be faced with the dual tasks of reducing carbon dioxide and other greenhouse gas emissions, while having to cope with an already changing climate.
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