Climate crisis: Rice yields experience larger declines in extreme weather conditions in India

rice india

In India, the yields from grains such as millet, sorghum, and maize are more resilient to extreme weather; their yields vary significantly less due to year-to-year changes in climate and generally experience smaller declines during droughts; but yields from rice experience larger declines during extreme weather conditions, finds a new study.

In a paper – “Sensitivity of grain yields to historical climate variability in India” – published in Environmental Research Letters (volume 14, number 6, June 13, 2019), Kyle Frankel Davis, Ashwini Chhatre, Narasimha D Rao, Deepti Singh and Ruth DeFries write:

“[C]ompared to all alternative grains — rice yields are significantly more sensitive to interannual fluctuations in monsoon rainfall on both irrigated and rainfed croplands.”

The scientists also write in the conclusion part of the research paper:

“[I]ncreased allocation of croplands to alternative grains can contribute to stabilizing grain production across a spectrum of climatic conditions. These results highlight the potential benefits of increasing alternative grain production in order to buffer against increasingly frequent climate extremes, especially considering that half of kharif grain production is rainfed.”

The paper said:

“[I]rrigation may only play a limited role in buffering rice yields in particular against increased rainfall variation.”

The researchers found:

  1. “[D]uring an extreme dry year, […] significant reductions in rice yields under all rice models considered [in the study].”
  2. “[A]lmost all rainfed grains — with the exception of finger millet — display some yield sensitivity to variability in monsoon temperatures.”

The study indicates:

  1. “[A]ll grains will likely experience some impacts from an increasingly variable climate but that the relative importance of precipitation and temperature variability varies between crops.”
  2. “Taken together with evidence of increasing temperatures, a changing monsoon, and more frequent climate extremes, this collectively indicates that rice yields may be particularly hard-hit.”

The analysis provides a comprehensive national assessment of the sensitivity of rainfed and irrigated grain yields to historical climate variability in India.

On the basis of the study results, the scientists write:

“[S]electively increasing coarse grains in the crop production mix may offer promise for enhancing the climate resilience of food supply in India. This approach may be combined with other strategies to enhance the resilience of grain supply against climate shocks including strategic reserves, improved access to and utilization of irrigation resource, and the development of high-yielding drought-tolerant varieties of India’s dominant crops. However, the relatively high yields of rice mean that in many districts a tradeoff between production levels and yield sensitivity will persist with coarse grains unless their yields improve. As such, any efforts to this end must take into account that a focus on developing the few traits desired for high-yielding crop varieties can often come with a loss in climate resilience (e.g. European wheat).”

In the conclusion part of the research paper, the scientists also write:

“The potential effects of climate variability on crop productivity are essential to consider in developing sustainable and resilient food systems.”

They added:

“Recent work also highlights that the potential improvements to the climate resilience of Indian grain supply through increased alternative grain production could also be complemented by other environmental and nutritional benefits. In particular, promoting the production of alternative grains offers the potential to reduce agricultural water demand, greenhouse gas emissions, and energy use while also alleviating certain micronutrient deficiency diseases (e.g. anemia). There also remains a large potential to reduce tradeoffs between efficient land use (i.e. yields) and high nutrient content for alternative grains through increased research efforts, as rice and wheat have received the bulk of the scientific focus since the start of the Green Revolution.”

The study adds to the empirical information needed for comprehensively assessing the potential co-benefits and tradeoffs associated with increased alternative grain production.

The researchers write:

“The extent to which crop production is vulnerable to climate extremes is an increasingly important consideration in developing adaptable and resilient food systems. Future work examining other agriculturally relevant climate variables (e.g. dry spells, monsoon onset) can enhance our understanding of the relationship between climate variability and crop productivity in India. The work presented here demonstrates that increasing alternative grains in India’s grain production basket can potentially reduce variations in supply in response to growing climate variability but that such interventions should be made selectively (both geographically and for the appropriate crops) in order to avoid any production shortfalls.”

The research team studied the effects of climate on five major crops: finger millet, maize, pearl millet, sorghum and rice.

These crops make up the vast majority of grain production during the June-to-September monsoon season – India’s main growing period – with rice contributing three-quarters of the grain supply for the season. Taken together, the five grains are essential for meeting India’s nutritional needs.

The scientists combined historical data on crop yields, temperature, and rainfall.

Data on the yields of each crop came from state agricultural ministries across India and covered 46 years (1966-2011) and 593 of India’s 707 districts.

The scientists also used modelled data on temperature (from the University of East Anglia’s Climate Research Unit) and precipitation (derived from a network of rain gauges maintained by the Indian Meteorological Department).

Using these climate variables as predictors of yield, they then employed a linear mixed effects modelling approach – similar to a multiple regression to estimate whether there was a significant relationship between year-to-year variations in climate and crop yields.

The study shows that diversifying the crops that a country grows can be an effective way to adapt its food-production systems to the growing influence of climate change, and increasing the production of alternative grains in India can offer benefits for improving nutrition, for saving water, and for reducing energy demand and greenhouse gas emissions from agriculture.

The scientists write in the introduction part of the paper:

“The variability of crop production from year to year depends in large part on the sensitivity of crop yields to variations in climate — a relationship with profound implications for food supply and rural livelihoods. The impacts of these yield anomalies on production can be compounded by reductions in cropping frequency and harvested area in response to climate variability. Drought and extreme heat reduced global grain production by one-tenth over the past half century. There is also evidence that climate-related crop failures contribute to a host of indirect and dire consequences including increased human migration (e.g. Bangladesh, Mexico, Pakistan) and conflict (e.g. Syria). With episodes of extreme climate expected to become more frequent, measures to buffer crop production against these stresses are a critical aspect of climate adaptation.”

They write:

“In India, climate variability has increased both spatially and temporally over the past 50 years. The country’s monsoon region has seen significant decreases in rainfall totals concurrent with enhanced daily precipitation variability. Extreme rainfall events have become more frequent and spatially more variable, and there have also been increases in the severity and frequency of drought since the 1970s. Projections also suggest an increase in climate variability and extremes across South Asia in the coming decades. These trends towards more uneven distributions of precipitation throughout the monsoon season — compounded by rising temperatures — are expected to adversely impact the yields of major crops in India.

“Driven by an increasing dominance of rice–wheat systems — where rice is primarily grown during the monsoon (kharif) season and wheat is grown during the winter (rabi) season, Indian grain production has more than tripled since the start of the Green Revolution, and the share of Indian grain production contributed by rice and wheat has steadily increased from 65% (1966) to 85% (2011). Currently rice accounts for 44% of annual grain production — the most of any crop — and 73% of grain production during the monsoon (kharif) season. Maize (15%), pearl millet (8%), sorghum (2.5%), and finger millet (1.5%) (i.e. alternative grains) contribute the vast majority of the remaining portions of monsoon grain production and are regionally important for rural livelihoods and diets, with roughly half of monsoon (kharif) grain production being rainfed. The ongoing homogenization of India’s grain production — combined with increasing climate variability — raises important questions about the vulnerability of its food supply to extreme climate events, particularly during the monsoon season. It is therefore important to understand not only to what extent the current mix and distribution of crop production in the country is susceptible to variations in temperature and precipitation but also whether certain crops offer superior resilience in the face of more frequent climate extremes.”


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