Mar 28 2014
India is awaiting a crop holocaust because of global warming
This week, a United Nation’s intergovernmental panel on climate change (IPCC) meeting in Yokohama, Japan, has sounded alarm for what looks like a much bigger and prolonged devastation in the making, with scientists suggesting that the contours of mankind’s greatest fear ever is only beginning to unfold.
IPCC, which brings together the findings of thousands of peer-reviewed research work from across the world once in every seven years has warned that world food output will come under serious pressure as temperatures go up in the next few decades of this century.
IPCC will release its fifth assessment report, titled “Climate Change 2014: Impacts, Adaptation and Vulnerability,” at the culmination of its Yokohama meeting. This is a very comprehensive assessment of the vulnerability of socio-economic and natural systems to climate change and options for adapting to it.
According to leaks in the global media, IPCC’s report card to be released on Monday predicts that by the end of the century, “hundreds of million of people will be affected by coastal flooding and displaced due to land loss.” A majority of people living in island nations and South Asia will be among the first to feel the heat worldwide. As a result, climate change is likely to affect crop output, reduce fresh water resources and drive up the risk of natural disasters. In the worst case, climate-related economic losses could reduce the global gross domestic product by 2 per cent, or $1.4 trillion annually, should temperatures rise by a modest 2.5°C.
The report suggests that people living in developing countries in the low latitudes, particularly those along the coast of Asia (like India, Sri Lanka and Bangladesh), will suffer the most, as climate change-related droughts and floods will lead to rise in food prices. For India, home to 1.2 billion people and set to emerge as the world’s most populous nation in the next 14 years, that indeed is a dire warning.
Agriculture is the mainstay of several economies in South Asia, including India. It is also the largest source of employment. The sector continues to be the single largest contributor to the GDP in the region. As three-fifth of the cropped area is rainfed, the economy of South Asia hinges critically on the annual success of the monsoons. In the event of a failure, the worst affected are the landless and the poor whose sole source of income is agriculture and allied activities.
When you consider that despite record foodgrain output in the past successive years, food prices have continued to hold high, IPCC’s warning is ominous. India already holds excess buffer stock of foodgrains at 80 million tonnes, much of it rotting for want adequate storage facilities. It is set to produce 263 million tonnes of foodgrains this year, including 106.5 million tonnes of harvested rice and up to 92 million tonnes of wheat ready for harvesting. This is up from 255 million tonnes a year ago. After peaking at over 20 per cent in 2009, food prices rose by an average of 11 per cent in 2010, 7.2 per cent in 2011 and over 5 per cent in 2012, before bouncing back to above 10 per cent for most of last year. IPCC warns that food prices will continue to rise, as crop yields will begin to drop by 2 per cent every decade.
IPCC says monsoon rain patterns are already being disrupted and desertification is spreading in semi-arid regions of western India and China. The Ganga and Brahmaputra river basins are set to witness larger and more frequent floods in the years to come, before eventually drying up forever as the Himalayan glaciers begin to melt. So food shortages will be the new normal.
IPCC has projected that output would actually increase slightly in the mid-to-high latitudes as average local temperatures increase by up to 1-3°C due to climate change, depending on the crop. However, at lower latitudes, especially in seasonally dry and tropical regions, crop output is projected to decrease for even small increases (1-2°C) in local temperature.
IPCC has, however, stressed that regional differences in the response of wheat, maize and rice output to the projected climate change is likely to be significant. The results of crop output projections indicate that crop output could likely increase by up to 20 per cent in east and southeast Asia, but decrease by up to 30 per cent in central and south Asia even if the direct positive physiological effects of CO2 are taken into account. In South Asia, there could be a significant decrease in non-irrigated wheat and rice yields for a temperature increase of greater than 2.5°C, which could incur a loss of 9 per cent to 25 per cent in farm-level net revenue. In India, an increase in winter temperature by 0.5°C is projected to translate into a 10 per cent drop in wheat production in the high-yield states of Punjab, Haryana and Uttar Pradesh. The reduction is expected to be lower in eastern India compared with other regions. This difference is due to relatively higher temperatures in the east (32.2/25.3°C) both during grain formation and filling phase, accompanied by lower radiation. Other studies suggest a potential 2 per cent to 5 per cent decrease in Indian wheat and maize output for temperature increases of 0.5–1.5°C.
According to one research estimate, rice production in India could decline by 14.3 per cent to 14.5 per cent by 2050, maize by 8.8 per cent to 18.5 per cent and wheat production by 43.7 per cent to 48.8 per cent, relative to the levels prevalent in 2000.
In some African countries, output of rainfed agriculture, which is important for the poorest farmers, could go down by up to 50 per cent by 2020. Further, warming above 3°C would have increasingly negative impact in all regions. Africa is likely to face an assault of crop failures, diseases and extreme weather events as a result of global warming.
A study by researchers at the Cranfield University and University of Reading is the first to provide robust evidence of how climate change will impact productivity of major crops in Africa and South Asia. Jerry Knox, the lead author on the study, compares and combines results from different independently published studies, and shows a consistent loss in yields of major crops (wheat, maize, sorghum and millet) in both regions by the 2050s. This systematic review and meta-analysis of data in 52 original publications from an initial screen of 1,144 studies extends previous works and confirms the threat of negative climate change impacts in Africa but also in South Asia.
Knox estimates that mean yield change for all crops will be –8 per cent by the 2050s with strong variations among crops and regions. For instance, evidence of yield reduction up to -40 per cent is detected in some regions of Africa, while no mean yield change is detected for rice in India.
According to Mark Howden, Commonwealth Scientific and Industrial Research Organisation (CSIRO), who is the lead author of the food security chapter in the forthcoming IPCC report, food by most crops is growing by only about 1 per cent per decade, at present. However, when climate change occurs, the average global crop output will decline by up to 2 per cent a decade.
Howden believes food crops will remain relatively stable with less than 1°C of warming. But as temperatures rise above that, they will literally begin to feel the heat. And the more temperature rises, the fewer will be crop production. “The confidence that things will get more and more negative is stronger and stronger, as we go out to higher temperatures,” argues Howden. More extreme weather will also mean the amount of food produced will vary wildly year-on-year.
In spite of the threat of loss in crop output in a warmer climate, it is important to keep in mind that developing countries in the tropics (like India) have the potential to more than offset such adverse impact by implementing more intensive agricultural practices and adapting agriculture to climate and environmental change. Indeed Africa, and to a lesser extent, South Asia are among the only regions of the world where there is untapped potential for raising agricultural productivity, since poor soil fertility and low input levels, combined with extensive agricultural practices, contribute to a large gap between the actual and potential output.
But then, recent studies suggest IPCC may have significantly understated the potential impact of climate change on agriculture and crop output. According to researcher Wolfram Schlenker of Columbia University and David Lobell of Stanford University, crop output losses across Africa (consistent with global warming of around 1.5°C) by 2050 are likely to be in the range of 18 to 22 per cent for maize, sorghum, millet and groundnut, with the worst-case losses of 27 to 32 per cent for the same crops.
As per the US environmental protection agency (EPA), crops grown the world over are affected by a number of climate change factors. For example, the change in temperature, amount of carbon dioxide (CO2) and the frequency and intensity of extreme weather events could have significant impact on crop output, where the interaction of these factors with crop output is very complex.
According to EPA, warmer temperatures may make many crops grow more quickly, but warmer temperatures could also reduce crop output. Crops tend to grow faster in warmer conditions. However, for some crops (such as grains), faster growth reduces the time that seeds have to grow and mature. This can in turn reduce the amount of crop produced from a given amount of land.
EPA believes that for any particular crop, the effect of increased temperature will depend on its optimal temperature for growth and reproduction. In some areas, warming may benefit certain types of crops that are typically planted there. However, if warming exceeds a crop’s optimum temperature, output can decline.
According to EPA, first, higher atmospheric CO2 level can increase crop output. The output for some crops, like wheat and soybean, for example, can increase by 30 per cent or more under a doubling of CO2 concentration. However, some factors may counteract these potential increases in output. For example, if temperature exceeds a crop’s optimal level or if sufficient water and nutrients are not available, output increases may be reduced or reversed.
Secondly, EPA believes that more extreme temperature and rainfall can prevent crops from growing. Extreme events, especially floods and droughts, can harm crops and reduce output. For example, in 2008, the Mississippi River flooded just before the harvest period for many crops, causing an estimated loss of $8 billion for farmers. Similarly, dealing with drought can become a challenge in areas where summer temperatures are projected to increase and rainfall is projected to decrease. As water supplies are reduced, it may be more difficult to meet water demand.
Thirdly, many weeds, pests and fungi thrive in warmer temperatures, wetter climates and increased CO2 levels, according to EPA. Currently, farmers spend more than $11 billion per year to fight weeds in the United States alone. The ranges of weeds and pests are likely to expand northward. This would cause new problems for crops previously unexposed to these species. Moreover, increased use of pesticides and fungicides may negatively affect human health.
The findings of the upcoming fifth assessment report differ from IPCC’s last report, which found crop losses in some areas would be offset by gains elsewhere. More negative impacts are now being observed than positive, as they were in the fourth assessment report.
Howden says measures for climate adaptation can improve output by about 10 to 15 per cent above what they would otherwise have been — enough to feed a billion people. As per Howden, adaptation can be effective at about 2°C of warming, but at 4°C the gap between production and demand will become increasingly large in many regions, even with adaptation. The work to be able to adapt food production to a hotter and more variable world must begin now.
Most recently, a new study in the UK on crop output and climate change found that climate change may reduce crop output as soon as 2030; that is, much sooner than earlier anticipated. Researchers from the University of Leeds found that global warming of only 2°C will be detrimental to crops in temperate and tropical regions, with reduced output of rice, maize and wheat from 2030s onwards. Andy Challinor, lead author of the study, says this research shows that crop output will be negatively affected by climate change much earlier than expected. Furthermore, the impact of climate change on crops will vary both from year to year and from place to place, with the variability becoming greater as the weather becomes increasingly erratic.
For the study, Leeds researchers created a new data set by combining and comparing results from 1,700 published assessments of the response that climate change will have on the output of rice, maize and wheat.
According to Leeds researchers, there will be an increasingly negative impact of climate change on crop output from 2030 onwards. The impact will be greatest in the second half of the century, when over 25 per cent drop in crop output will be increasingly common.
“Climate change means a less predictable harvest, with different countries winning and losing in different years. The overall picture remains negative, and we are now starting to see how research can support adaptation by avoiding the worst impact,” Challinor said. The study, recently published by the journalNature Climate Change, feeds directly into IPCC’s forthcoming WG II report.
Variation in crop yield projections decreases when a large number of climate models are considered, confirming the relevance of the expanded use of multi-model ensembles. Conversely, variation in crop yield projections increases when the crop model gets complex, especially when using process-based crop models over statistical models.
A different study conducted by Gerald Nelson and colleagues at the International Food Policy Research Institute, suggests that rice production in South Asia, one of the most affected regions in terms of crop production, could decline by 14.3 per cent to 14.5 per cent by 2050, maize production by 8.8 per cent to 18.5 per cent and wheat production by 43.7 per cent to 48.8 per cent, relative to the 2000 levels. India, the second largest producer of rice in South Asia after China, would be significantly impacted by this projection.
Although systematic reviews and meta-analyses conducted by Knox and Nelson can provide important insights about sign, magnitude and uncertainty of climate change impacts, a direct comparison among studies suffers from inevitable limitations. In particular the diversity of the studies selected for the meta-analysis, encompassing a range of different countries, scales, crops and methods (climate models and scenarios, crop models, downscaling technique), makes it difficult to aggregate crop yield projections to provide a consistent and precise impact assessment.
A rigorous multi-ensemble approach, with varying climate models, emissions scenarios, crop models and downscaling techniques, as recommended by Challinor, would enable a move towards a more complete sampling of uncertainty in crop output projections. In that sense, coordinated modelling experiments such as the ones conducted throughout the agricultural model inter-comparison and improvement project (AgMIP) are likely to improve substantially the characterisation of the threat of crop output losses and food insecurity due to climate change.
(Varun Dutt is a faculty at Indian Institute of Technology, Mandi; Knowledge Editor, Financial Chronicle; and, lead author of IPCC’s forthcoming WGIII fifth assessment report)