Extreme climate can halve crop yields: Study

Global research quantifies impact of climate extremes on staple crops maize, spring wheat, rice and soybeans

By Kiran Pandey
Published: Tuesday 07 May 2019

The frequency and severity of climate extremes is projected to further increase in most regions worldwide, which is likely to affect the agricultural productivity.

But, even as the global agricultural activity needs to be advanced by 1.75 per cent every year to meet the demands of nearly 10 billion people by 2050, the global food system is at risk, warns a new study.

Climate extremes like — droughts or heat waves significantly impact the yield of major staple crops around the world like — wheat, rice and maize and soybean, says the study — led by researchers from Australia, Germany, Switzerland and the United States.

The study underlines the importance of mitigating impacts of climate extremes on the global food system and adapting agriculture to changes during extreme events — to the extent it is possible — to meet future food demands.

Overall, year-to-year changes in climate factors during the growing season of maize, rice, soybean and spring wheat accounted for 20-49 per cent yield fluctuations, according to the study.

This shows that the extreme climate conditions especially the temperature has a significant impact on agricultural yield and needs to be understood for predicting yield variations in maize, soybeans and rice.

This global research studied the effects of climate conditions on yield during the growing season, using climate and climate extreme datasets with near-global coverage and a high-resolution agricultural database.

Irrigation can mitigate the stress

Extreme temperature had a stronger association with the yield than extreme precipitation, but the negative yield effects of high temperatures are intertwined with water stress and can be mitigated by irrigation.

The study recommends future research for further investigation on the use of agricultural drought indicators that capture both precipitation and temperature effects.

“Interestingly, we found that the most important climate factors for yield anomalies were related to temperature, not precipitation, as one could expect, with the average growing season temperature and temperature extremes playing a dominant role in predicting crop yields,” said Elisabeth Vogel from the Centre of Excellence for Climate Extremes and Climate & Energy College at the University of Melbourne, who led this study.

Hotspots critical for global production and adaptation planning

Focusing on the importance of considering climate extremes for agricultural predictions and adaptation planning, the study also provided an overview of critical regions that are most susceptible to variations in growing season climate and climate extremes. 

These regions include North America for maize, spring wheat and soybean production, Asia in the case of maize and rice production as well as Europe for spring wheat production.

The hotspots are mostly in industrialised, high-input crop producing areas, but the climate extremes are also critical in other regions, where the contribution to global production might be small, but the reliance of communities on subsistence farming is high.  

For example, maize yields in Africa showed one of the strongest relationships with growing season climate variability. It has been found to be highly dependent on climate conditions.

While Africa's share of global maize production may be small, the largest part of that production goes towards human consumption — compared to just 3 per cent in North America — making it critical for food security in the region.

With climate change predicted to change the variability of weather and increasing the likelihood and severity of climate extremes in most regions, this research highlights the importance of adapting food production to these changes.

Increasing resilience to climate extremes and adaptation to long-term climate change requires concerted efforts at local, regional and international level to ensure future food security, states the study.

In the Indian context

These findings do resonate with the Economic Survey of India which warned that climate change could reduce annual agricultural incomes in the range of 15-18 per cent on average, and up to 20-25 per cent for unirrigated areas.

In fact the proportion of dry days (rainfall less than 0.1 mm per day) have increased steadily over the last one decade, and extreme rainfall shocks resulted in a 12.8 per cent decline in kharif yields. A recent study published also showed the impact of climate change on wheat in India.
By 2050, India is likely to experience a temperature rise of 1-4 degrees Celsius and this is projected to have a detrimental effect on farmers in more than half of the country. Thus, this global research has regional relevance for India too.

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