precipitation and crop revenue on the other. This finding is consistent with studies on the impact of global warming on agriculture (Mendelsohn et al. 1994, 2003; Kurukulasuriya & Mendelsohn 2006). Another key result is a hill-shaped relationship between mean flow and net crop revenue. Further, we also find that andosols, irrigation and household size are positively correlated with crop revenue, while livestock ownership, farm size and wage rates are inversely correlated with revenue.

Estimated marginal impacts further show that crop revenue is elastic with respect to climate change, but less elastic with respect to temperature than to precipitation. The temperature elasticities suggest that global warming is harmful for agricultural productivity. Though precipitation elasticities are much higher than temperature elasticities, the marginal impacts suggest that the temperature component of global warming may have more serious repercussions than rainfall.

This study further predicts the impact of different climate change scenarios on Kenyan agriculture. We used two GCMs to do so: CCC and GFDL, which predict 3.5 _°_ C and 4 _°_ C changes in temperature by the year 2030 respectively and a 20% change in precipitation over the same period. The predictions show that long-term changes in temperatures and precipitation will have a substantial impact on net revenue, and that the impact will be more pronounced in medium and low potential zones than in high potential zones. The latter are expected to receive some marginal gains from mild temperature increases, holding precipitation constant.

Our analysis of perceptions and adaptation of farmers to climate change show that farming households in Kenya are aware of both short- and long-term climate change and some have implemented various adaptation mechanisms. The analysis also shows differences between the perceptions and adaptations of medium/low potential zone farmers and their counterparts in high potential zones. Diversification (changing the crop mix) is the most common adaptation measure, particularly in high potential zones, while water conservation, irrigation and shading/sheltering of crops are the main adaptation measures in drier regions.

These results imply that adaptation to climate change in Kenya is important if households are to counter the expected impacts of long-term climate change. The government should therefore play a more critical role in encouraging adaptations. Monitoring of climate change and disseminating information to farmers would be a critical intervention, while knowledge on adaptation measures could encourage both short- and long-term adaptations to climate change. To gather such knowledge requires a multidisciplinary approach involving soil scientists, hydrologists, climate experts and agronomists. Using this knowledge, farmers and local leaders should be sensitized, through extension network, to the implications of climate change, including the vulnerability of crop production and the necessity for adaptation strategies. Management of the scarce water resources in the country could generate more water for irrigation purposes, especially in the drier zones. Given the dwindling and fluctuating water resources in the country, the government needs to embark on recycling of waste water, which can then be used to save on available water. In addition, water harvesting techniques should be introduced to farmers and adoption encouraged, particularly in drier areas, to supplement any available water. In addition, protection, conservation and rehabilitation of water catchment areas and river basins is critical to ensure sustainable water supply. Policies that improve household welfare as well as access to credit are also a priority for both short- and long-term adaptation measures.

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