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Improving the livelihood of smallholder farmers
Climate Change and Agriculture
Agriculture’s role in climate change
Carbon dioxide (CO2) is the leading heat-trapping greenhouse gas. Human activities result in some 7 billion tons of carbon in the form of carbon dioxide annually, with fossil fuel use the largest single source. Since the Industrial Revolution, carbon dioxide concentrations have increased by about 30 percent, primarily due to the burning of coal, oil, and natural gas for industry, electricity-generation, and transportation, and, to a lesser extent, the oxidation of biomass and decomposition of soil organic matter from conversion of forests to agriculture. Agriculture's role in climate change is just starting to be recognized. Clearing trees for fields and pastures, transforming soil into cultivated land, flooding areas for rice and sugarcane production, burning crop residues, raising ruminant animals, and using nitrogen fertilizers all release greenhouse gases into the atmosphere. Global agriculture is estimated to account for about 20 percent of total anthropogenic emissions of greenhouse gases. Thus, agriculture plays a significant role in climate change. Cost-effective reductions in greenhouse gases can be achieved by: - Better managing agricultural soils, rangelands, and forests
- Improving the efficiency of fertilizer use
- Restoring degraded agricultural lands and rangelands
- Improving ruminants' digestion through better feed
- Improving rice farming to reduce the amount of methane escaping into the atmosphere
- Slowing deforestation by reducing slash-and-burn agriculture
and establishing appropriate tree plantations.
Forest and agricultural soils are potential repositories of carbon and could hold down concentrations of carbon dioxide in the atmosphere. Their potential for trapping additional carbon each year is high if farmers adopt improved management practices, including agroforestry. According to IPCC estimates, the potential for carbon sequestration in tropical ecosystems by the year 2010 is 125 megatons of carbon a year for croplands, 170 megatons for forests, and 240 megatons for grazing lands.
For the world's poorest farmers the global response to climate change could be an enormous opportunity to grow higher-yielding crops, to sustain healthier animals, and to upkeep more sustainable forests, and to improve their livelihoods; for all of us, the correct response could protect the environment for future generations.
For the world's poorest farmers the global response to climate change could be an enormous opportunity to grow higher-yielding crops, to sustain healthier animals, and to upkeep more sustainable forests, and to improve their livelihoods; for all of us, the correct response could protect the environment for future generations.
Source CGIAR
Impact of climate change on agriculture
Climate change is already affecting agricultural production systems and will continue to do so. The effects will not be distributed evenly as some areas may gain from the changes and others are likely to lose significantly. Five main factors affecting agricultural productivity are changes in temperature, precipitation, carbon dioxide fertilization, climate variability, and surface water runoff. Rising atmospheric concentration of carbon benefits crop growth and could offset yield losses from heat and water stress, but this ‘carbon fertilization' may not be significant in practice.
Predictions from crop-climate models show that in tropical countries even moderate warming (1oC for wheat and maize and 2oC for rice) can reduce yields significantly because many crops are already at the limit of their heat tolerance. But a small impact on global agricultural production is foreseen because negative impacts in tropical and most developing countries are offset by gains in temperate and largely industrial countries. For temperature increases above 3oC, yield losses are expected to occur everywhere and be particularly severe in tropical regions. In parts of Africa, Asia, and Central America yields of wheat and maize could decline by around 20-40% as temperature rises by 3-4oC, even assuming farm-level adjustments to higher average temperatures. With full CO2 fertilization the losses would be about half as large. Rice yields would also decline, though less than wheat and maize yields. These are conservative estimates because they do not consider the crop and livestock losses arising from more intense droughts and floods, and changes in surface water runoff. Agriculture in low-lying areas in some developing countries would also be damaged by flooding and salinization caused by sea level rise and salt water intrusions to groundwater aquifers.
Adapting agricultural systems to climate change is urgent. Adaptation can substantially reduce the adverse economic impact of climate change. Farmers are already adapting but many of them including poor populations in most affected areas are unable to quickly respond to drastic changes or emergency situations due in part to the lack of economic means. They will need additional help in adapting, especially where the costs are higher.
Carbon finance and climate change mitigation
The emerging market for trading carbon emissions offers new opportunities for agriculture to benefit from land uses that sequester carbon. The main obstacle to realizing broader benefits from the main mechanism for these payments – the Clean Development Mechanism (CDM) of the Kyoto Protocol – is its limited coverage of afforestation and reforestation. No incentives were included in the protocol for developing countries to preserve forests despite the fact that deforestation contributes close to a fifth of global GHG emissions, largely through agricultural encroachment. Negotiations for the period after 2012 should rectify this flaw. They could also explore credits for sequestration of carbon in soils (e.g. through conservation tillage), for low-emission technologies such as aerobic rice varieties, and for agroforestry in agricultural landscapes.
Source WDR 2008