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'Extreme Events' from Climate Change Could Threaten Global Rice Production, Warns IRRI Scientist

posted Nov 12, 2015, 5:50 PM by Gerardo Tomasito Laviña ‎(IRRI)‎ - In an exclusive interview to Oryza, Dr. Reiner Wassman, coordinator of the Climate Change Research at the International Rice Research Institute (IRRI) clearly highlights the importance of the impact of climate change on rice production in various countries and possible means of its mitigation. He also talks about the importance of technology in adapting to climate change phenomenon. Various issues on climate change in his works...

Oryza: Can you please highlight important issues in your research on climate change?

Dr. Reiner Wassman: Climate change has many facets including changes in long-term trends in temperature and rainfall regimes with increasing year-to-year variability and a greater prevalence of extreme events. The impacts of these changing conditions on agriculture are already being seen, yet there are still considerable gaps in our knowledge of how agricultural systems will be affected directly or indirectly by the changing climate, and what implications these changes will have for rural livelihoods. At this point, there is simply not enough information available about the impacts at scales that are relevant for decision making and research prioritization, thus, having an adverse effect on the global net agricultural production.
Climate change presents an additional burden on the world’s agricultural and natural resource systems that must cope with the growing food demand driven by population growth and higher incomes in developing countries. The challenge is compounded by the uncertainty and pace of climate change and its effects regionally. It is increasingly clear that climate change will affect agricultural productivity. The temperature and precipitation changes that accompany climate change will require farmers to adapt, but precisely where and how much is uncertain. At the same time, as a significant contributor of greenhouse gases and a potential sink for atmospheric carbon, agriculture can help mitigate climate change.

Oryza: Can you please elaborate on the impact of climate change on rice-producing countries in Asia?

Dr. Reiner Wassman: A gradual increase in temperature, as reflected in fewer cold days and more frequent hot days, is already discernable in most regions and will intensify in the future. In turn, higher temperature levels will further increase intensity and frequency of heat spells. This trend which is deemed almost certain for future condition has serious implications on agricultural production and human survival. Moreover, the increase in temperature will increase sea level due to (a) thermal expansion of sea water and (b) rapid melting of the glaciers and ice caps. As a consequence, fragile coastal and highly productive deltaic rice cultivation area will be more exposed to inundation and salinity intrusion.

In the more immediate term, however, changes in extreme events may exert a stronger impact on agricultural production as compared to gradual change in temperature and precipitation. On the other hand, the predictions of extreme climate events under future climate conditions are attached to considerable uncertainty, but in any case rice-producing countries should be prepared to more climate extremes.

Oryza: How does climate change exactly lead to increase in greenhouse gas (GHG) emissions? Which Asian country has the highest GHG emissions so far?

Dr. Reiner Wassman: The cause-symptom relationship is (a) increase GHG emissions are causing (b) climate change – and not the other way around.

According to the Food and Agriculture Organization of the United Nations (FAO, 2011), Asia has the highest GHG output from agriculture at 44%. The table below shows a more detailed country ranking among Asian countries in terms of agricultural emissions from rice cultivation:

Agricultural emission,   
rice cultivation   
(gigagrams CO2 eq)
  1. China
  2. India
  3. Indonesia
  4. Thailand
  5. Philippines
  6. Vietnam
  7. Myanmar
  8. Bangladesh
  9. Cambodia
  10. Japan

                                      Source: FAO Statistical Yearbook 2013

Oryza: You have been highlighting the importance of Alternate Wetting and Drying (AWD) irrigation method in reducing GHG emissions compared to various other crop management strategies. How does the AWD technique reduce GHG emissions and how economical is it compared to other techniques?

Dr. Reiner Wassman: Rice production is a source of the GHG methane which is produced by bacteria in flooded soils. Irrigating the rice paddy at distinct intervals without flooding during the vegetation period will reduce the emissions of methane.

Oryza: Which rice producing countries have adopted this technique so far? How does this technique influence yields per hectare?

Dr. Reiner Wassman: AWD has been developed as a water-saving technique and has been introduced through individual projects in several countries such as Bangladesh, Vietnam and the Philippines, but has not yet reached a broader dissemination. However, some similar irrigation schemes encompassing a single drainage period are part of traditional practices in China and Japan.

Oryza: Do GHG emissions depend on cropping systems? What are the possible mitigation methods?

Dr. Reiner Wassman: Rice is the only crop that is grown under flooded conditions, so there are no methane emissions from other crops such as wheat or maize. On the other hand, non-flooded crops emit more nitrous oxide, another GHG derived from nitrogen fertilizer, as rice production.

Oryza: You have been developing decision support systems on mitigation/adaptation through mobile phone apps. In what stage is this research?
Dr. Reiner Wassman: This refers to improved fertilizer (nitrogen) supply as a means to reduce nitrous oxide emissions. Some of these ‘apps’ are already in use in several countries but are still undergoing constant software improvements.

Oryza: How do you integrate the socio-economic aspects into planning of Climate Change adaptation/ mitigation? What kind of support do you expect from various governments?

Dr. Reiner Wassman: Farmer adoption will rely on incentives. For adaptation, we try to highlight improved resilience to current climate variability as opposed to the possible advantages to a (distant) future climate. Climatic problems such as drought and floods are already common in many regions, so that adaptation options such as tolerant rice varieties offer an immediate remedy. For mitigation, the benefits may not be so clear in the first instance because lower emissions do not render advantages as such. Incentives for adoption have to be derived from co-benefits, e.g. lower water demand. Depending on the specific situation of the farmer, AWD may save pumping costs or can lessen water deficits.

Oryza: How does burning of rice straw contribute to GHG emissions?

Dr. Reiner Wassman: Burning of rice straw causes environmental problems mainly in two ways: local air pollution and emission of methane. Rice straw is typically burned in piles on the field that entail incomplete combustion of carbon. One of the products of incomplete combustion is methane.

Oryza: Does soil have any role to play in increasing GHG emissions? If yes, what are the mitigation methods?

Dr. Reiner Wassman: Soil is the matrix for the methane-producing bacteria – as well as for the roots of rice plants – but soil is not the source of methane. Insofar, this seems to be the wrong target for mitigation other than water management.

Oryza: How are you collaborating with the governments of various rice producing countries in educating farmers about the impacts of climate change? How do farmers respond to such counseling?

Dr. Reiner Wassman: We see our role to provide technical expertise on adaptation and mitigation to policy makers. This policy advice is done at different scales, namely from local to provincial and national scales. In some case studies, we develop ‘road maps’ on adaptation and mitigation consisting of (1) geographic hot-spots of vulnerabilities such as aggravating flooding and salinity problems where introduction of improved rice cultivars is imperative and (2) suitability maps displaying priority areas for dissemination of mitigation.

Source: Oryza