Farming in SA under threat from climate change
There’s an assumption in the agricultural industry that the yields and prices of crops will vary according to local conditions, as well as supply and demand in local and international markets.
As a result, farmers understand that not every year will be profitable, but over the long run, all things being equal, the good years should outnumber the bad.
But is climate variability and risk changing?
The answer is yes. Scientific evidence which has become more robust over the past decade points increasingly to this reality.
So, what is changing, and what can be done about it?
Climate risk and climate resilience both need to be considered. If climate risk is increasing, resilience must be built up through measured and effective responses.
The most important climate change risk is increased temperature. This affects rainfall and seasonal patterns on a global scale. It also affects plants’ phenological growth (phases in the plant’s development which require certain thresholds of sunlight, heat and moisture) and physical growth, as well as animal growth and exposure to pests and diseases. Ultimately, it contributes directly to yield.
Temperatures are increasing in southern Africa faster than the worldwide average. The region has seen rises of up to 1⁰C over the past 100 years. This doesn’t sound like much. But it’s averaged over an annual cycle, and some individual stations have had daily temperatures increase by 3⁰C - 4⁰C since records began in the mid-20th century. Rainfall patterns are very hard to analyse, as the trends are rarely statistically significant. The average rainfall may not be changing. But there have been longer dry spells on top of which higher temperatures have led to increased evaporation. This has reduced the available water.
Future projections point to temperature increases of between 2⁰ C and 5⁰ C by 2100 (compared to pre-industrial temperatures). This depends on the future carbon emission pathway, but we have seen no real reduction in the rate of increase in CO₂ emissions, and thus expect the worst over the short to medium term.
Rainfall projections are loaded with uncertainty, but show broadly that the tropical and sub-tropical regions may experience more rainfall, and the Mediterranean regions may become drier.
The impact of climate change on agriculture is clear. The sector will suffer, which in turn will affect food supplies. The question is: what can be done about it? In my research, I set out a number of proposals that would help farmers mitigate the risk. But these require concerted effort on the part of government, agri-business and financial institutions.
These include a review of the existing cropping systems to assess their viability, adopting more sustainable methods (and perhaps crops), and intensive training in better techniques.