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Global warming and agriculture

March 14, 2010

By Ernesto Ordoñez
First Posted 04:27:00 05/04/2007

MANILA, Philippines — In the past week, we experienced unusually high temperatures. As Earth continues to warm, the climate will change in ways that may seriously disrupt our lives unless we immediately change some of our practices.

The Union of Concerned Scientists states: “Among the most severe consequences of global warming are a faster rise in sea levels; more heat waves and droughts; more extreme weather events producing floods and property destruction; a greater potential for heat-related illnesses and deaths, and the wider spread of infectious diseases carried by insects and rodents in areas previously free from them.”

The chart above from the UN’s Food and Agriculture Organization shows the global warming effects on agriculture:

Disastrous impact

Findings on staple food crops from the International Rice Research Institute (IRRI) indicate that for every increase of one degree Celsus in temperature in the tropics, yields decrease by as much as 10 percent.

The Intergovernmental Panel on Climate Change, a team of scientists that advises governments, estimates that the average global temperature in the tropics could climb by as much as three degrees Celsius by 2100.

The Independent Science Panel, a group of scientists from many disciplines, states: “There is now a consensus among experts in the field that, over the 21st century, the mean temperature of the earth will rise by no less than two degrees Celsius and possibly by as much as 5.8 degrees Celsius.” This means a decrease of as much as 20-50 percent in crop yields. With an increase in population of 2.3 percent a year in the Philippines, this would be disastrous.

The Hadley Centre in the United Kingdom estimates that the rise might be as much as eight degrees Celsius. This is because it took into account the effects of changes in vegetation. This happens through the destruction of rain forests, and changes in vegetation caused by global warming.

This factor is very important because it is an example of a harmful cycle that renews and strengthens itself. A rise in the earth’s temperature causes changes in vegetation: For example, the loss of rain forests that hold water and carbon. This leads to a rise in temperature, which changes the vegetation even further.

Cynthia Rosenzweig and Daniel Hillel, in their report on “The Potential Impact of Climate Change in Agriculture and Food Supply,” said studies found that vulnerability to climate change was greater in developing countries, which are located in warmer latitudes.

Having realized the imminent threat paused by global warming, the worst thing to do is take on a “bahala na” [leave it to chance] attitude and continue with our current practices. Instead, there should be a systematic study of what is to come, then launch a nationwide program led by the government to prevent or minimize the global warming dangers.

A part of this program is to shift from conventional way to sustainable agriculture. Conventional agriculture degrades the soil by leaving it bare, breaking up its tiny humus-containing aggregates, and failing to return plant residues. This has contributed to the atmospheric increase in carbon dioxide, methane, and nitrogen-oxide compounds — the greenhouse gases.

Professor R. Lal of the Ohio State University School of Natural Resources states: “Restoration of degraded soil is a win-win situation. While improving productivity through enhancing soil quality, restoration of degraded soil can also sequester carbon and minimize the risk of the greenhouse effect.”

At the farm level, changes in current practices can include several measures. Examples are the introduction of later-maturing crop varieties or species, switching cropping sequences, sowing earlier, adjusting the timing of field operations, conserving soil moisture through appropriate tillage methods, improving irrigation efficiency, and implementing proven effective technology.

Instead of an overdose in chemical fertilizers and pesticides harmful to both the land and the environment, a more balanced approach emphasizing organic and sustainable agriculture should be followed.

It is hoped that, as the planning of the 2008 budget begins with the newly elected senators and house representatives, the farmers and fisherfolk will unite with the Department of Agriculture in formulating a new program that specifically addresses global warming for the benefit of agriculture and the nation.

The author is chairman of Agriwatch, former undersecretary of agriculture, and former undersecretary of trade and industry. For inquiries, e-mail or call or fax +632 8522112.

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