Global warming will increase production in developed countries
Attempts to calculate the large-scale consequences of global warming for agriculture and food production, although difficult, do confirmed that most of the increase in production will come from the agriculture of developed countries, which mostly ‘benefit’ from climate change.
“And these countries will have to compensate for declines projected, for the most part, in developing countries with declines in agricultural productivity approaching between 20 and 25% for some countries like Mexico, Nigeria and South Africa,” said Bernard Seguin, a global bioclimatologist based at INRA, France, who presented his paper, on the consequences of global warming for agriculture and food production, to delegates at the British Society of Animal Science’s Livestock and Global Climate Change meeting, held recently in Tunisia.
And Dr Seguin warned that the resulting increase in the number of people marginally at risk of hunger – expected to rise from 380 million to 1,300 million by 2080 – could be underestimated due to the increased frequency and severity of extreme weather events.
Increased elevation of CO2 atmospheric concentration, which will impact on pastures as well as annual crops, will stimulate increased photosynthesis – between 10 and 20% with 550ppm for temperate species such as wheat, rice and soya – and, therefore, production.
“And higher elevated temperatures are generally favourable for growth in cold and temperate climates, except when they exceed the optimum and even attain detrimental thresholds in the case of extreme events, and are generally unfavourable for warm areas. For perennial species, like grass, warmer conditions will mean earlier spring growth and a significant increase of the length of the growing season,” he said.
“Changes in rainfall will more or less modulate the potential changes in plants resulting from these effects of temperature increase. It is certain that tendencies towards drier conditions in areas like the Mediterranean basin or the south of Africa will cancel out the positive potential impact of higher CO2 levels or milder temperatures.”
Dr Seguin added that crop models, used to simulate the effects of a climate change on crops currently cultivated, show that there will be adaptation, which will involve changes in the crop/livestock systems combining changes in varieties and cultural practices.
“And it is possible to estimate that yields will improve by between 10% and 15% in temperate regions where moderate to medium increases in local mean temperature – between 1°C and 3°C – along with associated CO2 increases and rainfall changes, will have a small beneficial impact on crop yields.
“At lower latitudes, particularly the seasonally dry tropics, even moderate increases in temperature are likely to have a negative impact on the yield of major cereal crops. And further global warming has increasingly negative impacts in all regions,” he said.
With regards to livestock, the model indicates the same tendency for pasture production. “It will be accompanied by changes in forage quality and grazing behaviour. And additional thermal stress on livestock has the potential to reduce productivity and conception rates.”
Presented to the British Society of Animal Science’s Livestock and Global Climate Change meeting, May 17 to 20, 2008, Hammamet, Tunisia.
Full details:
B Seguin: “The consequences of global warming for agriculture and food production.”
http://www.bsas.org.uk/Meetings_&_Workshops/Past_Meetings/ Presentation_08_03_seguin (pdf) summary (pdf)
For further information contact: BSAS on 0131 445 4508 or bsas@sac.ac.uk
