Warmer nights threaten rice crops across Asia

Tuesday, 10 August 2010 23:44 Perry Santanachote

Chiang Mai (Mizzima) - As if Cyclone Nargis, rat infestations and incessant drought were not enough to wilt rice production in Burma, farmers must now face the effects of global warming, according to research published on Monday.

Nargis had reduced yields by 40 per cent in 2008, the UN Food and Agriculture Organisation reported, but a study published in the US peer-reviewed scientific journal, Proceedings of the National Academy of Sciences, states that global warming has cut rice yields in parts of Asia between 10 and 20 per cent in the past 25 years.

Even small rises in global temperatures will drive down rice production in the region, the biggest grower of the grain that millions of world’s poor depend on as a staple food, the study warned.

The findings by a research team headed by economist Jarrod Welch of the University of California in San Diego showed that crops were affected by warmer nights, which require rice plants to respire more, thus leaving them without enough energy left to photosynthesise in the daytime.

The study included locations in Thailand, Vietnam and the Philippines – not Burma, but its climate is similar enough to have the same effect. Six years of data from 227 irrigated rice farms in six major rice-growing countries in Asia, which produces more than 90 per cent of the world’s rice.

“The findings on changing night-time temperature and the impact on rice yields from these nearby countries are relevant to Burma,” Dr. Roland Buresh, principal scientist at the International Rice Research Institute (IRRI) in the Philippines, said. “The climate would be comparable.”

Moreover, the Contribution of working group II (impacts, adaptation and vulnerability) impacts to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change in 2007 concluded that temperature increases of more than three degrees Celsius were stressful to all crops in all regions.

A study published in 2004 by Dr. Peng Shaobing of the IRRI initially investigated the increase in night temperatures and its effect on rice cultivation. Peng’s team found that grain yield declined 10 per cent for each rise of a degree Celsius in the dry season.

Although climate change is significant, Buresh said rice yields in Burma have bigger factors affecting crops because Burma’s rice fields are rain-fed versus the irrigated, intensive farming techniques seen in other Asian countries.

“The main factor affecting production in Burma is rain and inputs,” he said.

Inputs refer to fertilisers, chemicals and equipment used in farming.

Farmers are often strapped for money to purchase these inputs. The Post-Nargis Periodic Review III Tripartite Core Group made up of the UN, Asean and the Burmese military government reported that the provision of agricultural inputs remained limited and that farm yields were smaller than those before Nargis.

A rice farmer in the Irrawaddy Delta said he had not noticed a drastic rise in temperature until just last month.

“July became too hot to plant my seeds so I’ve had to wait,” he said.

He also said he was unaware of a large drop in his crop yields over the years, but factors such as the drought, especially post-Nargis, certainly made his job more difficult.

Even so, the government may be preparing for rice shortages. Mizzima reported last week that authorities from the Rangoon Division Peace and Development Council banned all rice shipments to Arakan State and Tenasserim Division without explanation. Also, many rice farmers in the delta have had to abandon their paddy fields in search of more viable work.