The impact of climate change on agriculture production is a serious concern to those working to meet the food demands of a
growing human population, as well as those working to preserve natural ecosystems and the services they provide. As data and research accumulate, the negative effects of climate change on potential food production for many regions of the developing world are being clarified. At the very least, these effects will raise the bar that technological innovation has to “jump”. As the suitable ranges for different crops shift, farmers in many parts of the world will also be faced with difficult decisions about what crops
to grow, and there will be mistakes and failures of adaptation. Natural ecosystems may have even greater difficulty adapting to climate change, since natural plant species move more slowly than human introductions. Since natural ecosystems provide many services to agriculture – including water regulation, pollination, pest control, genetic resources for new crop varieties and cultivars – this will also rebound on food production, as well as on other services such as biodiversity conservation, leisure and aesthetic pleasure. The most effective solution to limiting the impacts of climate change on food production is, of course, to mitigate climate change by reducing greenhouse gas emissions and increasing carbon sinks. This will be a vast undertaking affecting almost every sector of human activity.
The agricultural sector itself can contribute significantly. The planting of highyield varieties as part of the Green Revolution saved an estimated 170 million hectares of forest from cropping in Africa, Latin America and Asia between 1970 and 1990 – saving the equivalent of two to three years of total global carbon emissions (Gregory and others 2005). Converting to conservation agriculture with no tillage could reduce fossil fuel use in mechanized ploughing by 50 per cent and also lock up 0.1 to 1 tonne of carbon per hectare per year (FAO 2002). Agroforestry can increase the presence of trees in arable land and pasture, increasing carbon uptake. The agriculture sector’s emissions of methane can be reduced by changing cultivation methods in paddy fields, and by using feed additives that increase livestock digestion efficiency. Biogas plants can use methane from dung for energy generation. Nitrous oxide emissions from nitrogenous fertilizers can be reduced by changing the way the fertilizers are applied (Epstein and Mills 2005). Some degree of climate change is inevitable irrespective of any action taken to control greenhouse gas emissions, so adaptive policies are also required (Box 2). We will need what could be called a ‘Green Planet Revolution’ in crops and agricultural technology. Development of crops better suited to changing environmental conditions will need to be prioritized by national and international breeding and genetic modification programmes (Box 3).
Increased irrigation for double and triple cropping will be needed where renewable water supplies suffice. However, many areas
where potential rainfed cereal land may be reduced are also areas facing significant or critical water shortages (FAO 2005a) –
especially North Africa and South Asia. Here, water conservation techniques and methods to improve irrigation efficiency will be needed. These include rainwater harvesting and storage, crop varieties that need less water and the use of drip irrigation methods, which deliver the water when and where it is most needed. Moisture-conserving methods such as minimum tillage agriculture and sustainable agricultural practices such as windbreaks, agroforestry, intercropping, and relay cropping can help maintain soil moisture (FAO 2005a). Agricultural policies at the national level that reward good practices, such as the use of
integrated pest management, could provide farmers incentives for change. Information networks that provide early warning of
seasonal changes or extreme events could minimize losses by providing farmers crucial information on what kind of seeds to plant, and when, to reduce risks. Such early warning networks already exist in some parts of the world. For instance, the US National Oceanic and Atmospheric Administration (NOAA) has set up a series of Regional Outlook Forums across Africa, Latin America and the Caribbean, and southeast Asia, bringing together national and international meteorologists to produce consensus-based seasonal forecasts (DFID 2004).
However, the scale and depth of expected changes may be too great in some countries for national measures to suffice, so increased levels of technical support and aid may be required. All told, climate change will present a vast range of challenges to agriculture and its ability to feed and provide livelihoods for human populations. As well as working to limit the extent of climate change, constant adaptations will be required.
|Box 3: The potential of biotechnology
The Green Revolution was based on the breeding of new high-yielding crop varieties. We will need a new generation of varieties adapted to changes induced by global warming. Breeding will continue to be important, but gene technology will help to speed up the process. This process can be expensive, and vulnerable countries will require international assistance, for example through the Consultative Group on International Agricultural Research network of agricultural research centres. Many of the conditions
we can expect in the future are already problems for marginal areas: drought, heat stress, salinity, pests and pathogens.
Drought and temperature are two forms of stress resistance particularly relevant to climate change. A number of studies have demonstrated that genetic modifications to crops can increase drought tolerance. Breeding
and genetic modification for heat resistance will also be essential. However, caution should be exercised to
minimize potential socio-economic, health and environmental impacts of introducing genetically modified crops.
Sources: Cheikh and others 2000, FAO 2004, Pilon-Smits and others 1995, Drennen and others 1993, Kishor and others 1995, Hinderhofer and others 1998
|Box 2: Agricultural technology and policy options for climate change
Measures to reduce agriculture’s greenhouse
gas emissions and increase carbon uptake
● Removal of subsidies and introduction of
environmental taxes on fossil fuel energy based inputs.
● Improvement of fertilizer use efficiency.
● Improved management of livestock and crop waste to reduce methane.
● Use of livestock and crop wastes for biofuel.
● Development of rice varieties emitting less methane.
● Restoration of degraded lands.
● Expansion of agroforestry and reforestation. Measures to promote adaptation to climate change
● Sustainable production of bio-fuels for other sectors, for instance transport.
● Development and distribution of crop varieties resistant to drought, storms and floods, higher temperatures, salinity and
emerging pests and pathogens.
● Improvement of water use efficiency through:
● no-till/conservation agriculture in rainfed areas; and
● appropriate water pricing, management and technology in irrigated areas.
● Promotion of agroforestry to increase ecosystem resilience and maintain biodiversity.
● Maintenance of livestock mobility in pastoral areas subject to drought. Measures to reduce food insecurity
● Reduction of rural and urban poverty.
● Improvement of roads and communications in disaster-prone areas.
● Removal of agricultural export subsidies that limit markets for poor farmers.
● Slowing of rapid population growth rates.
● Development of early-warning and stormforecasting systems.
● Preparedness plans for relief and rehabilitation.
● Introduction of flood- and storm-resistant and salt-tolerant crops.
● Introduction of land use systems to stabilize slopes and reduce the risk of soil erosion and mudslides.
● Building of homes, livestock shelters and food stores above likely flood levels.
Source: FAO 2002