What are some possible effects of global warming on agriculture and forestry?

It is difficult to predict the future, but in 2001 the IPPC issued a Report: Climate Change 2001: Working Group II: Impacts, Adaptation and Vulnerability (See the link below).

Here are some of the suggested impacts on agriculture and forestry:

  • Climate change will affect crop yields and irrigation demands.
  • Climate change will affect the composition and geographic areas of forests as well as product health and productivity.
  • Water Resources will be affected: water supply, quality and competition for water.
  • The following quote illustrates how much we rely on our ecosystems for goods and services: "Forests and woodlands provide many goods and services that society values, including food, marketable timber and non-wood products (fuel, fiber, construction material), medicines, biodiversity, regulation of biogeochemical cycles, soil and water conservation (e.g., erosion prevention), carbon reservoirs, recreation, research opportunities, and spiritual and cultural values." The report goes on to say that changes in climate are likely to affect all of these, especially the socio-economic systems.
  • Moderately warmer weather and increased CO2 in the atmosphere may help some crop growth (up 30% in the case of rice, soy and wheat), but with increased temperatures the grain yield drops 10% for every 1˚C rise above 26˚C.
  • Agricultural areas may suffer erosion from increased wind and water from short term changes in weather.
  • The growth of agricultural pests (weeds, insects and pathogens) under climate change is being studied with varying results. For example, higher temperatures increase the severity of rice leaf blast epidemics in cool subtropical zones, but in warm humid subtropics higher temperatures lower the severity of the epidemics.
  • Farm animals are affected by warmer temperatures, influencing their performances in growth, milk and wool production, reproduction, health and well-being.
  • Increased temperatures may lead to increased demand for water from agriculture and wildlife, including farm livestock. It may also lead to reduced water availability.
  • Adaption costs for agriculture, including retraining farmers for new practices, as well as the provision of new irrigation may be considerable.
  • The cost of basic food will rise, especially with temperature rises of more than 2.5˚C, as agriculture will not be able to absorb increased costs.
  • "Africa is projected to experience marked reductions in yield, decreases in production, and increases in the risk of hunger as a result of climate change."
  • Cold winters will no longer kill the eggs of the boreal forest insect pests.
  • Studies in Britain suggest that 10% of all Nature reserves could be lost in a few decades.
  • The effect of increased concentrations of CO2 on decomposition, plant productivity, and carbon storage could be just as damaging as the effects from climate change.