How Farmers can Adapt to a Changing Climate

Backgrounder

How global warming affects the weather
Have you heard of global warming? The earth is getting warmer because human actions – such as burning coal, oil and gas for energy – are increasing the levels of ‘greenhouse gases’ in the earth’s atmosphere. These gases, which include carbon dioxide, methane and nitrous oxide, stop the sun’s heat from reflecting back into space. Heat gets trapped in the earth’s atmosphere, and this increases the temperature on the surface of the earth. Because of the increase in greenhouse gases, world temperatures will rise between 1.5 and 4 degrees over the next century. This may not sound like much, but it will have a large impact on farmers.

As the temperature rises, the weather will be affected in different ways all over the planet. Drought is likely to get worse in some areas, especially in the African grasslands, where rainfall is expected to decrease and become more unpredictable from year to year. The rising temperature will also cause more moisture to evaporate more quickly from the surface of the earth. As the air and soil become drier, it may be more difficult to grow crops such as maize.

In other areas, especially coastal regions, higher temperatures will be accompanied by higher rainfall. Coastal lands and small islands will be at risk from rising sea levels and more intense storms. For example, if the sea level rises by one metre, 17% of the land in Bangladesh will disappear. Low-lying parts of China, Southeast Asia, and west and central Africa would also be submerged or damaged.

How will global warming affect local agriculture?
We’ve already seen how an important crop like maize might be more difficult to grow, as a result of global warming. Other crops will be affected, especially in tropical and subtropical areas. Crop decreases are likely because:

1) Many varieties of rice may not set grain if temperatures become hotter, and

2) There will be less water for crops if rainfall decreases and evaporation increases

Food production will also be affected by:

• an increase in the frequency of extreme weather such as storms, floods and droughts
• longer growing seasons in cool areas
• dramatic changes in the distribution and quantities of fish and seafood
• an increase in pests and diseases.

The following are examples of some potential impacts of global warming in different parts of the world.

In Africa:

• Increased droughts could seriously reduce the amount of food available.
• Millet yields may decline by 63%-79%.
• Yields of freshwater fish may increase, although the mix of fish species could be altered. While some fish species will fare better at increased temperatures, for example by increasing reproductive and feeding efficiency – other species are not as well adapted to higher temperatures, and their numbers are likely to decrease.
• Tsetse fly infestations could expand into more southerly areas of Zimbabwe and Mozambique, move westward in Angola, northeast in Tanzania. At the same time, their numbers may decrease in some of the areas where they currently exist.

In the Middle East and drier parts of Asia:

• Wheat production in some areas may decline due to increased temperatures.
• There will probably be acute shortages of water.

In Latin America:

• Yield decreases are expected for several major crops in Mexico, Central America, Brazil, Chile, Argentina and Uruguay.
• Livestock production may decline due to water shortages in temperate grasslands.
• Extreme weather events such as floods and hurricanes may hurt livestock and crop production.

In China and cooler parts of northern Asia:

• Rice, wheat and maize yields will probably decline.
• Yields could increase in northern Siberia, and decrease in southern areas of Siberia.
• As water warms, aquaculture operations can shift to warm-water species, though diseases will have to be carefully managed.

In tropical Asia:

• Rice, wheat yield and sorghum yields are expected to decline.
• Crop production will decrease by 12% overall in India, with several coastal areas being most negatively effected. Other areas are predicted to benefit to a small extent from warming.
• In some areas, for example in Pakistan, increased runoff in some river basins may cause more flooding and waterlogging, and increase the amount of salt in the soil.

What can farmers do?

Farmers in your audience probably already use effective methods to limit damage from weather. You can encourage them to do more damage control, and to adapt and improve their methods. For example, both soil and water degradation are likely to get worse with global warming. So methods to conserve soil and water will be particularly useful.

When you are preparing your radio program, talk to local experts (research stations, national weather services, your country FAO office) to find out how climate change is likely to affect your region. Then you can outline strategies that may be useful for the farmers who listen to your program. Remember to explain these strategies to your listeners. You might want to refer back to past DCFRN scripts. We have noted some scripts that would be helpful. [If you don’t have these scripts, see our newsletter for further instructions.]

1. If your area is vulnerable to storms, hurricanes, typhoons and floods:

• Establish tree cover to protect coastal regions (see example of mangrove plantation below).
• Plant crops that are least vulnerable to strong winds. Root crops are a good choice. (See script 58.11 – Grow and eat nutritious yams)
• Avoid using slash and burn methods to clear land.
• Avoid planting temporary crops on steep slopes. (See script 44.9 – Save soil on sloping land)
• Establish grass barriers. (See script 43.3 – Prevent erosion with vetiver grass)
• Keep land covered with vegetation or mulch at all times. (See scripts: 34.1 – More with mulch; 50.4 – Farmers in Nicaragua challenge El Nino; 58.5 – Grow your own fertilizer by planting cover crops with maize)
• Use recommended planting material to establish windbreaks. (See script 44.2 – Windbreaks protect crops and soil)

Protecting coastal regions with mangrove plantations
Typhoons strike the coast of Vietnam 8 to 10 times per year. They often break sea dykes and destroy aquaculture farms. To provide a barrier in front of the dykes, and protect coastal land, the Vietnam Red Cross established 2000 hectares of mangrove trees. The mangrove plantations are also used to harvest and market valuable sea products such as shrimp, crabs, and cultured seaweed. Shortly after completion, the mangrove plantation was hit by the worst typhoon in a decade. But there was no significant damage to the dyke and aquaculture pond systems.

2. If your area is at risk from drought, desertification, and soil and water degradation:

In drier areas, lower rainfall and higher evaporation are predicted to further degrade soil and water resources, and hasten the process of desertification. So farmers will need to practise soil and water conservation. They can:

• Capture and store runoff water. (See scripts: 54.3 – Garden while you shower; 54.7 – Catch rain from your roof)
• Use tillage methods that conserve soil and water, and limit erosion. (See scripts: 50.7 – Stop soil erosion with living plant barriers; 55.9 – Trees and terraces prevent hillside flooding; 50.2 – Farming for the future, some practical methods)
• Add organic matter to the soil, such as crop residues, compost, and manure. (See scripts: 33.9 – Where to find compost materials; 47.8 – Make something with nothing in a rubbish garden; 61.6 – Dr. Compost talks about compost piles)
• Keep the soil covered with vegetation at all times. Select and cultivate cover crops. (See script 58.2 – Improve rice yields without buying fertilizer)
• Practise agroforestry. (See scripts: 55.7 – A farmer turns wasteland into rainforest; 55.1 – Choose the right trees to grow with crops; 54.1 – Trees and rain; 54.2 – How trees store water and protect springs; 58.4 – Growing maize with trees; 27.2 – Trees in your garden give you fertilizer)
• Dig planting pits in dry areas. (See script 54.5 – Infiltration pits catch water for crops)
• Plant drought-tolerant crops and crop varieties. (See script 54.9 – These crops will help you through the drought)
• Choose and experiment with effective, long-term storage techniques. (See script 48.10 – Use hot peppers to protect stored grain)

Improving techniques for long term storage
In Sudan, the rains are failing more and more frequently. To store crops for longer periods of time, farmers in Sudan have modified the matmura, their traditional sorghum storage pit. Traditionally, farmers poured sorghum into the matmura pits until a dome shape was formed. Then they would add a layer of chaff on top. The traditional pits were one and a half metres deep, but now farmers make shallower pits, about 50 cm deep. This keeps the grain drier for two reasons. First, it reduces leakage through cracks. Second, less moisture gets into the grain. With less moisture, there are fewer insects, which improves the quality of the grain. Farmers have also increased the amount of chaff that is placed on top of the sorghum. Now the chaff is 50 centimetres deep and extends for about one metre around the filled pits. These new innovations on their traditional practice have increased the safe storage period.

3. If you live in a cooler area:

In cooler areas, the growing season may be a month longer, or more. Here are some methods to discuss on your program:

• Test and select crop and crop varieties most suitable for the newly extended season.
• Plant earlier in the season.
• Grow a second short-season vegetable crop, when possible. (See script 53.10 – Intercropping: radio spots)
• Plant heat-resistant varieties of wheat and other crops.

4. If rainfall in your area will be more uncertain:

Effective and long-lasting crop storage is going to be more important than ever. Also, you could advise farmers to:

• Harvest rainwater and runoff water. (See scripts: 44.3 – Cross ridging holds precious rainwater on the land; 54.7 – Catch rain from your roof; 61.4 – Farmers and scientists harvest rainwater in India)
• Plant drought-tolerant crops and crop varieties. (See script 58.7 – The advantages of growing and using finger millet; 58.10 – My friend the dependable sweet potato)
• Use soil and water conservation methods. (See script 43.5 – A woman farmer fallows with trees; 54.5 – Infiltration pits catch water for crops)

An example of water catchment
Several kinds of planting pits can be used for water catchment. One kind of planting pit is the zai hole. Zai holes are a traditional method of catching and holding runoff water in sub-Saharan Africa. They are used in soil that is so badly degraded that water cannot penetrate it.

During the dry season, a hole that measures 20 x 20 centimetres is dug to a depth of ten centimetres. The hole is filled with crop residues or manure. These materials attract termites, which make holes in the pit. The termite holes increase the amount of water that can penetrate the soil when the rains come. Millet and other crops are planted in the zai holes. In Burkina Faso, farmers using this method have improved their yields several times over. The zai holes also protect seedlings from strong winds. Even when rainfall is much lower than normal, zai holes have worked well in most cases.

5. In most regions of the world, farmers will benefit from planting different crops and raising different kinds of livestock, or changing plant varieties and livestock breeds to address the new farming conditions they will encounter.

On your program, you could discuss how to select new or alternative crops, or crop varieties:

• Grow salt-tolerant crops or varieties if soil becomes contaminated with salt.
• Grow drought- and heat-tolerant crops in areas where drought and heat increase with climate change. (See script 58.7 – The advantages of growing and using finger millet)
• Grow cassava where rains are uncertain, because it can be stored in soil for a long time before being harvested.
• Grow short rice cultivars in areas where strong winds are a problem, because they are more resistant to winds.
• Plant rice and other crops earlier in the year in areas where higher temperatures are the major problem. When rice flowers during the hottest time of the year, it can be killed. Another strategy is to plant varieties which flower early in the morning, thus avoiding the hottest time of day.

Remember:

As always, when deciding on topics for discussion on your radio program, learn about local traditional techniques that may be useful in addressing some of these climate change issues. Also, as much as possible, learn from, talk to, and discuss the ideas and practices of farmers in the community and in your listening audience.

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