Does climate change really have negative impacts on agricultural production?

Economic research shows that climate change is associated with declines in agricultural production and revenue in sub-Saharan Africa. However, previous research has omitted the fact that farmers are actively changing their agricultural practices to adapt to climate change. In a recent study researchers used what is known as the Ricardian method, which measures climate effect through comparing agricultural net revenue changes. One feature of the method is that it includes farmers' adaptation activities by comparing farmers' net revenues in different climate situations. They found that revenue is negatively affected by higher temperatures and rainfall during the hot rainy season, but during the cooler dry season, revenue and temperatures are positively related.  
 
In an attempt to accurately measure climate impacts, economists from Columbia and Yale universities developed the Ricardian method to capture the changes in farmers' agricultural practices. To make this study accurate, authors Stephen A. Wood, of Columbia, and Robert O. Mendelsohn, of Yale, selected the Fouta Djallon area of West Africa, which features different climate conditions along low to high elevations but has no variance in biophysical and socioeconomic conditions. Villages were randomly selected from the listprovided by  localagencies. Research data was provided by 126 farmers from 38 villages in northern Guinea and southern Senegal.
 
Past crop-production models haven't accurately reflected the climate impact because farmers' adaptation strategies are overlooked. The Ricardian model can fill in this gap by measuring changes in agricultural revenue. In contrast to previous research, the new study shows that precipitation during the hot rainy season is related to net revenue loss. The authors theorize that extreme weather might be connected to this loss, but say that further research is needed.
 
The results reveal that agricultural revenue loss is correlated withincreasingtemperature  during hotrainy season in the Fouta Djallon area of West Africa. This is consistent with previous research for sub-Saharan Africa on continent-wide assessments.The researchers also note that during the cooler dry season, revenue is positively correlated with higher temperatures and participation. Also, revenue loss during increasing rainy season could be outweighed by gain during warmer winter months.