Climate Change: Implication for Agriculture

Introduction

Climate change has been a natural phenomenon in the geological history as corroborated by paleontological, limnological and stratigraphical evidence, once in every few million years, (the impacts of climate change too were spread over few million years) which provided ample time for flora and fauna to acclimatize with the then-changing natural environs. What makes the currently-prevailing climate change differ from the past is that its nature is anthropogenic, i.e., man-made – this inference is backed by strong scientific evidence. It is fructification of the industrial processes ushered post-Renaissance (circa 1500 onwards), with rapid strides in science and technology placing tools of massive destruction in the hands of humanity. In a span of mere 500 years, humanity has virtually denuded the forest, altered the chemistry of atmosphere and drastically depleted the vitality of seas and oceans to the extent that only 4% of it remains ‘living.’ Since the natural process of climate change has been shrunk to 500 years, the time of consequences too have squeezed and being felt acutely by humanity.

Climate change, as I view it, is purely redistribution of water within the different segments of hydrological (or water) cycle, as almost all of its repercussions are generated either due to excess and/or lack of water (figure 1.1). The different processes, involved in the hydrological/water cycle on Earth’s surface, underground and atmosphere, are shown in figure 1.2.

Climate Change and Agriculture

The nature, extent and magnitude of prevailing climate change has already exceeded the boundaries of the Earth and its consequences will adversely affect, practically encompassing each and every aspect of our life – economic, social, cultural, oceans, mountains, freshwaters, forests, agriculture, public heath, industrialization, life-styles and so on and so forth. The most profound adverse impact will be on agriculture, as about 60% of world’s population, directly or obliquely, still depends on agriculture for their livelihood, especially in the developing countries of Asia, Africa and Latin America. Let us glance over some important parameters having a bearing on agricultural production which are shown in table 1.1 and are self-explanatory.

Six of the ten countries, most vulnerable to climate change, are in the Asia-Pacific. Bangladesh tops the list followed by India, Nepal, Philippines, Afghanistan and Myanmar. In Bangladesh, for example, about one-fifth of the nation’s population would be displaced as a result of the farmland loss estimated for a 1.5 m sea-level rise. The Maldives Islands in the Indian Ocean would have one-half of their land area inundated with a 2 meter rise in sea level.

 

Role of different factors in Climate Change Scenario on Agriculture

S N	Climatic element	Expected changes by 2050’s	Confidence in prediction	Impacts on agriculture
1.	CO2	Increase from 360 ppm to 450 – 600 ppm (2005 levels now at 379 ppm)	Very high	Good for crops: increased photosynthesis; reduced water use
2.	Sea level rise	Rise by 10 -15 cm Increased in south and offset in north by natural subsistence/rebound	Very high	Loss of land, coastal erosion, flooding, salinization of groundwater
3.	Temperature	Rise by 1-2oC. Winters warming more than summers. Increased frequency of heat waves	High	Faster, shorter, earlier growing seasons, range moving north and to higher altitudes, heat stress risk, increased evapo-transpiration
4.	Precipitation	Seasonal changes by ± 10%	Low	Increased drought risk, soil workability, water logging, irrigation supply, transpiration
5.	Storminess	Increased wind speeds, especially in north. More intense rainfall events.	Very low	Soil erosion, reduced infiltration of rainfall
6.	Variability	Increases across most climatic variables. Predictions uncertain	Very low	Changing risk of damaging events (heat waves, frosts, droughts, floods), affecting crops and timing of farm operations and final yield

Source: IJSRP, Vol.4, April 2014

Impact of Climate Change on Indian Agriculture

One of the critical issues in Indian agriculture is the high proportion of rainfed agriculture in the part of the country climatically classified as ‘semi-arid tropics’ (SAT). Rainfed agriculture in SAT is particularly vulnerable to climate change. In 1999–2000, rainfed agriculture as a whole accounted for roughly 60% of net sown area, amounting to nearly 87.5 million hectares, out of a total of 142 million hectares. In SAT States of Andhra Pradesh, Gujarat, Maharashtra, Karnataka, Rajasthan, Tamil Nadu and Madhya Pradesh, rainfed agriculture accounted for 72.8% of net sown area. Rainfed agriculture in SAT carries a much higher degree of risk, and is characterized by high variability in production, low yields and low returns, often not even covering the cost of cultivation for several crops in many regions. This has been a critical factor behind the farmers’ suicides during the last two decades, beginning of which almost coincides with the period now supposedly known as beginning of climate change.

A 2^°C rise in temperature and a concentration of 450 ppm of CO₂ would cause some loss of yield in rice production in all regions of India. This is a vital issue, since the best possible scenario emerging from current climate knowledge suggests that the world is likely to move towards a 2^°C rise in temperature and a CO₂ concentration of 450 ppm. The impact of increased temperature on a few crops is shown in table 1.2.

Impact of Temperature on Yield of Selected Crops in India

Crops	Topt (0C)	Timax (0C)	Yield@Topt (t/ha)	Yield@280 C (t/ha)	Yield@320 C (t/ha)	% Decrease (280 C-320 C)
Rice	25	36	7.55	6.31	2.93	54
Soybean	28	39	3.41	3.41	3.06	10
Dry bean	22	32	2.87	1.39	0	100
Peanut	25	40	3.38	3.22	2.58	20
sorghum	26	35	12.24	11.75	6.95	41

Source: Rao (2008)

Notes: Topt = optimal temperature; Tmax = maximum sustainable temperature; t/ha: tonnes/ha

Some other trends are also expected, like –

• Kharif crops to be impacted more by rainfall variability while Rabi crops by minimum temperature
• Wheat is likely to be negatively impacted in Rabi due to terminal heat stress
• Rice in the IGP to be impacted both by temperature and water availability
• Legume crops like soybean and groundnut are likely to be benefited due to increased temperature/CO₂ if water availability is not limited
• Milk yield in livestock to be impacted during heat waves
• Changes in breeding season in marine fisheries with shift in seasonal catch
• Significant negative impact on commercial poultry due to heat stress
• More opportunities for rain water harvesting due to high intensity rainfall but greater loss of top soil due to erosion.

There is another dimension to agriculture – the physical location of agricultural fields. For instance, if the farming fields are located in an area already identified as vulnerable and susceptible to climate change, then agricultural activities will be doubly hit. This is the case especiallywith coastal, mangroves and mountain areas. Let us look at the Himalayan Mountain, as it has already been identified officially as critical area and has been accorded special status owing to fragile nature of its ecosystem whose vulnerability is increasingly with each passing day, courtesy ever-increasing human intervention.

Agriculture in Himalayan Mountain Ecosystem

All available scientific evidence strongly shows that climate change has already set in and since 1990 every preceding year has been hotter and the trend continues till date (with 1 or 2 exceptions). Correspondingly, its impacts on mountain agriculture are also becoming prominently visible, as we found during our field work in the villages situated in different river valleys of Mahakali/Sarda river basin, for example –

• In the extremely upper reaches of Ladhiya river valley, there used to be heavy snowfall which lasted 3-4 weeks resulting in thick accumulation of snow on the ground, creating an environ conducive for apple cultivation and the entire area was known for it. Since last 8-9 years, the snowfall has drastically reduced and now has come to almost nil! For instance, this year in 2017, snowfall happened just once, for a few hours and the quantum of snow on the ground was so little that all of it melted in just 3-4 hours. Consequently, all the apple cultivation has stopped since last 10 years and apple cultivation has now shifted to further higher areas.
• The effects of climate change also include the effects of interaction with other factors of pests and weeds. Pear cultivation has hit drastically as its plants have been affected by a strange growth of some kind of green weed at the apical parts, which makes the plant wilt and non-fruiting. Vast areas of pear cultivation have been destroyed by this strange weed. The household economy of dozens of villages has been adversely affected.
• Flowering season of a tree Buransh has become pre-mature. Normally its flowering starts from April-end or May-beginning but in last 2-3 years it has started flowering in mid-March. During our field trips in March second week we found trees of Buransh thickly decked with flowers all along our traverse. Buransh is a very important plant for local economy and villagers are worried over the pre-mature flowering.

There are various other ecological/ environmental/ anthropogenic factors which are affecting agriculture adversely, like, loss of top soil (due to depletion of vegetal cover), debris of mass movement accumulated in agricultural fields (largely due to road-building + other developmental activities), menace of wild animals (owing to disturbed prey-predator ecological chain), etc.

In a nutshell, the impacts of climate change on agriculture bears a grave implication for India and needs to be addressed by immediately taking up development of climate resilient species, improving the vitality of soil, reducing rain-fed area, advanced water efficient irrigation practices, evolving coping mechanism, imparting knowledge to farmers (through Krishi Vikas Kendra), etc. To achieve these and other related objectives adequate resources – financial, technical, and managerial – needs to be channelized in a unified manner for the optimization of desired results.

Author – Arun Singh