scenario underpinning this prediction is the IPCC Special Report on Emissions Scenarios (SRES) emissions scenario A1 without stabilization. Regional climate change impacts are drawn from the UK Meteorological Office’s global climate model (Schlesinger & Malyshev 2001). The global climate sensitivity to an equilibrium doubling of CO2 is set at 2.5°C.

The country specific changes in temperature and precipitation associated with this scenario are presented in Tables 3 and 4 respectively. Using alternative input assumptions or an alternative global climate model would naturally alter the predicted impact. The climate change scenario is evaluated at the year 2050 by which time a globally averaged temperature increase of 1.1°C is expected, allowing for continuing negative forcing from sulphates.

Productivity impacts associated with this particular climate change scenario are presented in Table 5. These impacts are calculated by using the estimated equation to predict the change in perceived land values under the climate change scenario and expressing it as a function of land values under current climatic conditions. Note carefully, however, that what this procedure yields is an estimate of the impact of climate change on agriculture using current rather than future technology. There are three other important caveats. First, the predictions do not account for changes in productivity due to the so-called carbon dioxide fertilization effect and, second, these estimates do not account for attendant changes in runoff even though such changes might be important. Insofar as minimum runoff contributes significantly to perceived land values it is expected that this will amplify the adverse impact of climate change on productivity. Regional predictions of changes in runoff are not available. Third, recalling the discussion in earlier sections, these productivity impacts exclude transitional costs.

There is a very clear pattern portrayed in Table 5. Those countries suffering the greatest loss in productivity, namely Burkina Faso and Niger, already have very hot climates, whereas countries with cooler climates such as Ethiopia and South Africa suffer relatively little. Thus even when the predicted changes are relatively homogeneous across countries the impacts can be very different depending on the existing climate upon which these changes are overlaid. These results suggest that climate change could have a devastating impact on agriculture in Sub-Saharan Africa but more modest impacts elsewhere. Nevertheless, it is notable that climate change has a negative impact on productivity in all 11 countries.

Despite differences in the countries under consideration, the precise climate change scenario and details regarding the implementation of the Ricardian technique, these findings resonate with those from earlier studies. Mendelsohn and Dinar (1999) summarize the results from three existing studies, suggesting a change in productivity of between -3% and +2% for +2°C warming in the US, between -9% and -3% for +2°C warming in India, and between -5% and - 11% for +2°C warming in Brazil.

# **6. Conclusions**

The Ricardian approach attempts to quantify the economic damage to agriculture arising as a result of climate change. Its main advantage over other approaches is that it attempts to account for farmer adaptation.

Ricardian studies take a measure of agricultural performance and regress it on various structural and environmental characteristics of land in an attempt to infer the implicit value of 12