INTERNATIONAL AGRICULTURAL RESEARCH AND FOOD SECURITY

Climate Change and Agriculture

John Zillman

Dr Zillman is President of The Academy of Technological Sciences and Engineering and former Commonwealth Director of Meteorology

Climate strongly influences the crops that can be grown and the livestock that can be raised in the various parts of the world, and hence it affects the agricultural productivity of individual countries and regions and ultimately the total global food supply. The influence of climate results from the sensitivity of plants and animals to the various weather elements—rainfall, temperature, cloud, wind etc. Most crops and creatures have adapted to live successfully within fairly narrow bands of hot and cold, wet and dry. Not only are the long term-patterns of agricultural production closely tied to the 'normal' climate of the region, but the year-to-year and decade-to-decade variability of climate have major influences on agricultural production.

• Over the past century most of the worst famines and the most widespread death from starvation have been directly caused, or severely exacerbated, by failure of the monsoon or of the 'normal' seasonal rains, sometimes coupled with other extreme climatic events such as heatwaves and bushfires.
• Any study of future food supply for the global population must rely on predictions about our future climate, since the global climate is in a constant state of change—either through natural fluctuations due to internal processes within the global climate system in the short- or long-term, or trends due to human influence.
• Climate scientists now have the tools to produce reasonably reliable forecasts of broadscale climate patterns for months and seasons ahead. This information is critical to decisions on the planting of crops and on stocking and destocking strategies for individual farms and the rural community as a whole, and substantially influence the behaviour of agricultural markets around the world.
• Less well understood, but of profound significance for future global food security, is the potential impact of humans on climate and food supply through the release of greenhouse gases, especially carbon dioxide, and the long-term trends in global and regional climate that the climate system models suggest will result.
• Expert bodies such as the Intergovernmental Panel on Climate Change (IPCC) carry out regular assessments to ascertain the possible impacts of future greenhouse-gas-induced climate change on local, regional 17 July, 2006uly, 2006mate envisaged over the next century that could impact on agricultural production and global food supply include:
  • increased levels of carbon dioxide that could lead to increased production of certain crops, due to a so-called 'CO2 fertilisation effect';
  • increased aridity of presently well watered, rain-fed agricultural lands, leaving some crops and sources of food supply no longer sustainable;
  • higher temperatures that could exceed the survival limits of certain crops (causing harvests to fail) and also lead to heat stress in livestock (reducing production of meat and other animal products);
  • more severe weather events that lead to erosion and other forms of soil depletion and reduced agricultural production;
  • adverse climatic changes that could lead to new outbreaks of weeds, pests and diseases and reduced productivity of the land.
• However, not all the impacts of climate change on agriculture are expected to be negative and individual countries could benefit significantly from warmer and wetter climates—Russian agriculture could benefit substantially from the much warmer temperatures that the climate models suggest would result from continuing emission of carbon dioxide.
• For the world as a whole, the IPCC has concluded that the impacts of climate change on agriculture could result in only small percentage changes in global income with positive changes in more developed regions and smaller or negative changes in developing regions.
• There is still much that is not understood about the impacts of climate change/global warming on food supplies including, most importantly, who will be the agricultural winners and losers in a greenhouse-warmed world.

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