Climate change

Climate change

Throughout the 20thcentury, the global average temperature rose by about 0.5oC, and most of the high temperature records were concentrated in the 1990s. There is strong evidence that human-induced greenhouse gas (GHG) emissions contribute towards this “global warming”, which encompasses a change in most climate variables, including their variability patterns.

While solar radiation and rainfall are major climatic resources, climate is also the single main factor behind the variability of agricultural production in developing and developed countries alike.

Global warming may thus have profound effects on agriculture1and food security. Crop agriculture, forestry and livestock are directly involved as sources or sinks of GHG, but they are also among the most vulnerable victims of the foreseen changes.

Although there is no consensus on what will happen to agricultural environments and production, and at what pace, the following consequences are generally accepted by the scientific community:

* climate has considerable inertia, and cannot be reversed over a short period of time;
* future scenarios are uncertain and significant reduction of the uncertainties will require a decade or more;
* water vapour concentrations will increase in the lower atmosphere, and global mean precipitation could increase by 1.5 to 2.5 % per 1 °C of global warming;
* sea level rise may reach about 50 cm by 2100.

The response to the changes by organisms is relatively easy to assess at the eco-physiological level. It includes, for instance, shorter crop cycles, CO2fertilisation, modifications of coastal/deltaic agriculture, modified crop/animal and pest/disease relations…

Major methodological difficulties are associated with the extrapolation of impacts to the global scale. The literature stresses the possibility of a modification of the current crop geopolitical balance, human population movements and increased global insecurity.