Raghu MurtuguddeMay 29, 2019 11:57:42 IST
India is a vast country with disparate climate variability and change signals from north-to-south and east-to-west. The mix of field crops like rice, wheat, jowar, corn and soybean, as well as speciality products like vegetables, flowers, nuts, fruits, etc, are also vastly different across the subcontinent. To understand the climate sensitivity of agriculture across such complex terrain that has a complex mix of climate variability, change and agricultural activities, it is important to carefully choose a metric to measure it.
Recent studies of climate sensitivity of agriculture in the US may point to an answer.
Climate impacts on agriculture typically consider temperature and precipitation impacts on crop yields, profits per acre and such. These are considered partial measures of productivity since they don't include the sum total of all inputs and output to track the overall return on investment or ROI and the overall sensitivity of this ROI to climate variability and change.
Economics offers a metric that is ideal for measuring the aggregate agricultural productivity and its sensitivity to climate. It's what's called the Total Factor Productivity (TFP), which considers all necessary inputs and outputs. An inclusive measure like this is necessary since partial productivity doesn't add up like a mathematic formula to give total productivity, i.e, partial productivity measures may not accurately represent the sensitivity of a particular economic sector like agriculture to climate variability. TFP, on the other hand, can capture exactly that.
Climate impact analyses of partial productivity measures can lead to conflicting results on the vulnerability of agriculture because of region-specific climates, specific crops or regions being considered in the analyses and whether the target is agricultural productivity or economic profitability. TFP can avoid these pitfalls.
To wit, the impact of temperature and precipitation on crops and speciality products in the US show negative impacts on crop yields and profits from them. Yet, TFP computations show that US agriculture has grown nearly monotonically since World War II. This aggregate production, however, has become increasingly sensitive to climate variability even as it has seen more-or-less steady growth. Advances in technology and regional specializations in crop selections, irrigation, and livestock production, are responsible for most of the agricultural growth as well as the increased sensitivity to climate.
Clearly, regional differences in climate and its impact on TFP must be understood to get the full-picture on where climate sensitivity comes from and how it can be mitigated in a warming world with more climate extremes. A close look at the history of TFP offers better guidance for the future in terms of minimizing climate sensitivity of TFP by distributing risks with appropriate regional choices of crops, livestock, and speciality products.
A study published in the Proceedings of the National Academy of Sciences in December 2018, presents the long term trend and variability of US agricultural TFP, which is the ratio of total agricultural output to the number of units of input. The outputs here include crops and livestock as well as other components of the agricultural economy such as goods and services. The inputs are land and labor as well as the capital and other resources such as water and energy.
The highlights of the study are that the climate sensitivity of TFP has a large variability across the US with a relatively more rapid increase in climate sensitivity in some regions such as the Midwestern states and for the non-irrigated crops in the Eastern United States. On the other hand, livestock production shows negligible climate sensitivity. Moreover, technologies underlying agricultural practices and regional specialization influence TFP for both crops and livestock.
Climate sensitivity of TFP will clearly depend on crop selections. For example, states in the US Midwest show high TFP sensitivity to summer temperatures and rainfall because they largely rely on non-irrigated cereals and oilseeds. As the background temperatures warm, the same temperature anomaly (say, a 2-degree C-spike in summer temperature) would be more harmful to crops because they ride on a higher summer mean temperature. A comparison between TFPs during the years 1960-1982 and 1983-2004 thus shows that a 2 degree C heatwave produced an almost 30 percent-drop in TFP during the latter period, whereas, the reduction in TFP was only about 11 percent for the former period.
In the same vein, crop selection can also reduce climate sensitivity of TFP. The southeast-to-southern plains, as well as the Southwest and Northwest of USA, have experienced a reduced climate sensitivity because of increased livestock and poultry, which have been protected against climate change by technologies such as heating and cooling of abodes for livestock and poultry. The crops and speciality products are also made climate resilient with irrigation.
The summary of these findings is that increased climate sensitivity in one region may be more than compensated by a lack of sensitivity or reduced sensitivity in other regions to drive national-level TFP increases with a combination of regional choices and specializations.
Growth in TFP is explained by advances in technology like access to deep groundwater, refrigeration and large-scale irrigation technology. The dominance of US agriculture across the world can be traced back to sustained investments made in research, extension and development. These have yielded various advances like breeding technology and food processing. There is also diffusion from other investments in satellites and smartphones, weather and climate forecasting, information technology, etc. The US accounts for only about 20 percent of the global investment in agricultural R&D but produces over 40 percent and 38 percent, respectively, of the world’s corn and soybeans.
For a developing country like India where more than 60 percent of the employment is generated by the agricultural sector, which is at mercy of a decreasing mean monsoon with an increase in climate extremes, TFP offers the best metric to measure the climate sensitivity of its vastly inhomogeneous agricultural sector. More importantly, it may also be the best metric for developing the most optimal regional specialisations for managing food production without losing sight of its water and energy demands as well.
Selections of crops, speciality products, and livestock are now being driven purely by economic incentives and are supported by unsustainable exploitation of resources such as groundwater. Some policies may, in fact, have unintended consequences. India also needs to develop effective policies and strategies for optimizing food production without jeopardising its own INDC targets.
Tracking its agricultural enterprise with the most appropriate metric is a basic imperative. Mapping India’s agricultural TFP for the historic period and analysing its seasonal and regional variability and trends may serve these goals effectively.
The author is a Professor of Atmospheric & Oceanic Science and Earth System Science at the University of Maryland, currently a Visiting Professor at IIT Bombay.
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