Authors: Katherine M Nelson, Reiner Wassmann and Björn Ole Sander, International Rice Research Institute
At the COP 26 Glasgow, Vietnamese Prime Minister Pham Minh Chinh joined more than 100 countries in signing a methane emission reduction pledge. Rice production contributes almost half of Vietnam’s total methane emissions and is the centre of action for reducing the powerful greenhouse gas. Reaching the goal of reducing methane emissions from rice by 30 per cent will require transforming millions of smallholder practices to low-emissions cultivation.
Methane is a short-lived pollutant with a lifetime of around 12 years, compared to carbon dioxide’s several hundred years. But methane’s global warming potential is 28 times that of carbon dioxide, which means reducing methane emissions can curb global warming with comparably quick effect.
Rice production is a major contributor to global anthropogenic methane emissions and Vietnam is one of the few top rice-producing countries to sign the global methane pledge. The signatories agree to take voluntary actions to collectively reduce global methane emissions by 30 per cent by 2030. The feasibility of this pledge depends on the realistic levels of methane reduction at the national level.
According to Vietnam’s Third National Communication, national methane emissions were 99.5 metric tons of carbon dioxide equivalent (MtCO2e) in 2019. Irrigated rice accounts for 43 per cent of this at 42.7MtCO2e. Assuming a uniform reduction in methane emissions across all sectors, the 30 per cent target translates to an annual reduction target of 12.8MtCO2e for irrigated rice production alone.
In the updated 2020 Nationally Determined Contribution, Vietnam committed to reducing overall emissions by 9 per cent unconditionally and by 27 per cent conditional on international funding. A 9 per cent reduction in the rice sector would equate to 3.8MtCO2e. The national strategy for achieving emission reduction in rice outlines pragmatic and economical methods of controlled water management, reduction of straw burning and conversion of inefficient rice land for other uses. Various crop management systems, including the Sustainable Rice Platform standard and the System of Rice Intensification, could disseminate mitigation practices such as alternate wetting and drying, and mid-season drainage.
Achieving the 30 per cent methane reduction target would require another 9MtCO2e of methane reduction in the rice sector. An approximate 5.5MtCO2e reduction would be feasible, but will require greater targets and investments — reliant on international finance for low-emissions rice farming practices — than are currently outlined in national plans.
Investments are needed to improve existing canals and pumping facilities to enable controlled water management. These efforts must be backed up by enhanced training and an awareness campaign to encourage better water management behaviour. The total mitigation from this transition is estimated at 9.5MtCO2e or a reduction of approximately 22 per cent. This target is ambitious but feasible — the additional 8 per cent has to be regarded as aspirational at this point. The remaining 8 per cent will require a paradigm shift in agriculture policy prioritising emission reduction as an overarching goal in rice production.
The government could also consider improvements in the management and use of rice straw by incentivising its adoption for off-field purposes in circular economy approaches. This option could reduce methane emissions further but the current lack of detailed data impedes estimation of its mitigation potential. A possible trade-off with soil health should also be considered when planning for large-scale straw removal. Investments in research and scaling which have not yet left the scientific sphere — innovative fertiliser management, soil additives or ultra-short duration and low-emission varieties — could also contribute further to reaching the reduction goal.
While the numbers are pointing towards the target, the challenge is introducing a set of mitigation options to millions of farmers across Vietnam. Low-emission practices have previously been successfully implemented. Through its provincial extension program, An Giang — a major rice producing province in the Mekong River Delta — successfully promoted good management practices, known as ‘one must do, and five reductions’. Low-emissions programs have contributed to a reduction of over 2 MtCO2e per year, in farming systems with good irrigation and track record of advanced production practices. These conditions cannot be assumed as the standard throughout the country.
Vietnam’s participation in the methane reduction pledge represents an opportunity to tap into international climate financing. These funds could channel resources into green agricultural development projects in rural regions and secure funds for low-income farming populations heavily threatened by climate change. Additionally, participants commit to the highest tier of IPCC inventory methodologies and to improve the transparency, accuracy and comparability of national greenhouse gas inventory reporting. This will require coordination among various government, private and international institutions and could create trickle-down effects that will benefit global greenhouse gas reduction efforts as well as Vietnam’s rice exports to environmentally conscious consumers.
Katherine M Nelson is a climate change specialist at the International Rice Research Institute, Hanoi, Vietnam.
Reiner Wassmann was climate change coordinator at the International Rice Research Institute, Hanoi, Vietnam until his retirement in 2020.
Björn Ole Sander is a senior climate change scientist at the International Rice Research Institute, Hanoi, Vietnam.