Farming in the Future

We have published several articles recently on the importance of the agricultural sector and the challenges of food security and degradation of arable land. While much of the urban population remains dislocated from the process of farming, the reality is that this industry, above all others, keeps us alive. So what does the future hold for farming? Agriculture and food security has already touched on the issues of decline in agricultural productivity resulting from land contamination, poor land management and unsustainable use of water resources, and so we will now consider the implications of increasing atmospheric CO2 concentrations and the climate changes that this is widely expected to bring about.

CO2  is fundamental to photosynthesis and therefore plant growth. An increased concentration in CO2 will result in a process known as CO2 fertilization, where primary productivity will increase in response to the extra CO2 available in the atmosphere. Assuming that crop growth in a particular region is not limited by light, nutrient or water availability, this process of fertilization will increase crop yield relative to the increase in atmospheric  CO2.

As temperatures increase around the globe, the regions of arable land will likely shift to higher latitudes. While lower latitudes become to hot for their current land uses, areas in the higher latitudes that were previously too cold for farming will become viable. Assuming that there is no conflict for land use in these newly viable areas, and ignoring the plight of farming communities in the lower latitudes whose livelihoods have been taken away, then this pole ward shift in arable land is not likely to create a reduction in agricultural yield in the land dominated northern hemisphere. The story is different in the southern hemisphere however because much of the available arable land is near the southern coasts of countries in South America, Africa and Australia. In particular, Australia stands to lose much of its wheat cropping region if regions of arable land shift to higher latitudes.

Agricultural yield is also significantly affected by extreme weather events such as storms, cold snaps and heat waves, all of which are expected to increase in the coming decades. Particularly severe storms and extended periods of frost, high temperature or drought can be catastrophic to local agricultural production, resulting in crop damage or even total crop destruction over entire regions. While the overall impact of these regional extreme weather events can be difficult to model or predict, the impact of a warming climate and increased  CO2 can be examined with more confidence. In a recently released Australian study taking into account a warming climate and CO2 fertilization, it was found that crop yield in the nation's largest agricultural region is expected to decline by 5-30% relative to present yields by 2050 (Potgieter et al 2012). These findings become more alarming when the fact that the increased damage to crop yields by extreme weather events is not accounted for in this model.