Tag Archives: rainfall

Global warming may thwart food production

Sun.star Davao
Henrylito D. Tacio
November 08, 2010

November 08, 2010″THE global warming is very simple,” said Dr. Robert Watson, chair of the Nobel-winning United Nations Intergovernmental Panel on Climate Change (IPCC). “We are increasing emissions of greenhouse gases and thus their concentrations in the atmosphere are going up.”

Greenhouse gases produce the greenhouse effect, which traps heat near the earth’s surface, maintaining a relative constant temperature.

However, many human activities increase the amount of greenhouse gases in the atmosphere. As concentrations increase, the temperature of the earth also rises.

“Climate change means much more than higher global temperatures,” pointed out Heherson T. Alvarez, who convened the Asia-Pacific Leaders Conference on Climate Change in Manila when he was still with the Senate. “Global warming could result in a wide range of catastrophic consequences.”

Rising temperatures is expected to spur changes in rainfall patterns.

“Weather patterns (in the Philippines) may change with projections of higher rainfall and drier summers,” said Dr. Rodel D. Lasco. “These could adversely affect millions of hectares of farm lands. In the rainy season, there will be more frequent floods and in dry season, there will be less water available for irrigation. Overall, it threatens food security of our country.”

“Global warming is more disastrous to the agricultural industry of the Philippines and its neighboring Asian countries than in other parts of the world,” noted Dr. David Street of the US Argonne National Laboratory.

The Laguna-based International Rice Research Institute (Irri) said global warming can reduce rice yields. Rice is the principal food for over 60 percent of mankind. It is particularly important to Asia where over half of the world’s population lives.

An Irri study showed that rice plants could benefit from higher levels of carbon dioxide in the atmosphere, but an increase in temperature up to four degrees Celsius would “nullify any yield increase.”

Water resources are especially vulnerable to climate change. “In a warmer world, we will need more water to drink and to irrigate crops,” said the London-based Panos Institute.

“Water for agriculture is critical for food security,” pointed out Dr. Mark W. Rosegrant, a senior research fellow at the Washington-based International Food Policy Research Institute (IFPRI).

“The link between water and food is strong,” said Dr Lester R. Brown, president of Earth Policy Institute, also based in Washington, D.C. “We drink, in one form or another, nearly 4 liters of water per day. But the food we consume each day requires at least 2,000 liters to produce, 500 times as much.”

This explains why 70 percent of all water use is for irrigation. An estimated 40 percent of agricultural products and 60 percent of the world’s grain are grown on irrigated land.

“Agriculture is by far the biggest consumer of water worldwide,” Irri said. For instance, to raise a ton of rice, you need a thousand gallons of water.

But there could be less water to go round, as underground water reserves in coastal areas are flooded by sea water, as sea levels rise and as evaporation losses from reservoirs and rivers and flooded fields grow.

Rising sea levels are seen by many scientists as the most serious likely consequence of global warming. In a series of journals, Science reported that global warming could trigger the death of coral reefs, with coral bleaching being the clearest sign.

“When subjected to extreme stress (like high temperature of surface water),” explained Worldwatch Institute’s John C. Ryan. “Corals jettison the colorful algae they live in symbiosis with, exposing the white skeleton of dead coral beneath a single layer of clear living tissue. If the stress persists, the coral dies.”

The Philippines has about 27,000 square kilometers of coral reefs, said Dr. Angel C. Alcala, former environment secretary. As fishing grounds, they are thought to be 10 to 100 times as productive per unit area as the open sea. An estimated 10-15 per cent of the total fisheries come from coral reefs.

“Coral reef fish yields range from 20 to 25 metric tons per square kilometer per year for healthy reefs,” said Alcala.

About 80-90 per cent of the incomes of small island communities come from fisheries. “The fishing communities who depend on the coral for their catch will be affected,” said Abigail Jabines, climate and energy campaigner for the Southeast Asia section of Greenpeace.

Unknowingly, agriculture is also a contributor to the global warming problem. Methane is a gas created naturally as a waste product of anaerobic bacteria (living with little or no oxygen). These bacteria produce methane gas in waterlogged soils and wetlands, but also in human-produced environment such as rice paddies.

“An estimated 19 percent of the world’s methane production comes from rice paddies,” said Dr. Alan Teramura, botany professor at the University of Maryland in the United States. “As population increase in rice-growing areas, more rice, and more methane – are produced.”

Scientists claimed that one molecule of methane from decaying rice paddies is about 10,000 times more efficient in heating up our planet than one molecule of carbon dioxide emitted by a gasoline engine.

Aside from rice paddies, cuddling animals like cattle also contribute 14 percent while animal waste is source of five percent of the global methane production.

Irri said concentration of methane in the atmosphere has more than doubled during the past 200 years.

As early as 1986, Swedish Nobel Prize laureate Svante Arrhenius sounded the warning of global warming. But he was totally ignored; nobody listened. Today, his alarm has become a global concern.