Impact of climate change in India: An agro - ecological zone level analysis

20 Aug, 2009 . 19 mins read

A detailed look at the possible impacts of climate change on the different agro - ecological zones demarcated in India

India is gifted with heterogeneous landforms and variety of climatic conditions such as the lofty mountains, the raverine deltas, high altitude forests, peninsular plateaus, variety of geological formations endowed with temperature varying from arctic cold to equatorial hot, and rainfall from extreme aridity with a few cms (<10 cm) to pre humid with world's maximum rainfall (1120 cm) of several hundred centimeter.

This provides macro relief of high plateau, open valleys, rolling upland, plains, swampy low lands and barren deserts. These varying environmental situations in the country have resulted in a greater variety of soils. Therefore, the systematic appraisal of agro-ecological regions has tremendous scope in grouping relatively homogenous regions in terms of soil, climate and physiography and conducive moisture availability periods (length of growing season) in planning appropriate land use.

1) Impact on the high-land agro-ecological region

2) Impact on the arid agro-ecological region

3) Impact on the tropical wet agro-ecological region

4) Impact on the tropical wet and dry agro-ecological region

5) Impact on the humid sub-tropical agro-ecological region

6) Impact on the semi-arid agro-ecological region

Here's a close look at the possible impacts of climate change on the different agro-ecological regions of the country

1) Impact on the high-land agro-ecological region

It represents the area of the north-western Himalayas, north Kashmir, covering Ladakh and Gilgit districts with an area of 15.2 m ha, occupying 4.7 per cent of the total geographical area (329 m ha) of the country. This region is characterized by mild summer and severe winter with mean annual temperature of less than 8 degree Celcius and mean annual rainfall of less than 150 mm. The ecoregion shows sparse forest trees.

The area is under non-agricultural uses. The major part of cultivated area is under vegetables. However, the production per unit area is low. The millets, wheat, fodder, pulses and barley are next in order and their yield ranges from 400 to 700 kg/ha.

Among the cultivated fodders, the production of alfa-alfa is more dependable. Apple and apricot are the major fruit crops grown in the area. Among the livestock, mule dominates, while sheep, goat and yak stand next in order. This zone is known for grazing (by pashmina goats).

High land area also includes the eastern Himalayan agro-ecoregion encompassing northern hilly parts of West Bengal, northern parts of Assam, Arunachal Pradesh and Sikkim States. It occupies an area of 9.6 m ha, representing 2.9 per cent of the total geographical area of the country. The climate of the region is characterized by warm summer and cool winter. The annual rainfall is 2000 mm

High land region also comprises western Himalayas, covers Jammu and Kashmir, Himachal Pradesh and north-western hilly areas of Uttar Pradesh.

In general, Jhum cultivation is the traditional farming. It is practiced with mixed cropping on the steep slopes under rainfed condition at an interval of 3-4 years. Another type of traditional practice is the cultivation of millets on upland terraces and potato, maize, millets and paddy in valleys. In the lower valleys, rice, maize, millets, potato, sweet potato, mustard, sesame and pulses are grown under rainfed as well as irrigated conditions. At places cotton, mesta and sugarcane are also grown both under rainfed and irrigated conditions. In the hilly areas, vegetables and plantation crops like tea, and medicinal plants, and horticultural crops like pineapple, citrus fruits, apple, peer, peach, and banana are grown on terraces. The natural vegetation comprises subtropical pine forest and temperate wet evergreen forests, subalpine forest, etc

Constraints

Severe climatic conditions restrict the choice of crops.
Steeply sloping landforms encourage heavy runoff resulting in severe erosion hazards.
Deforestation for shifting cultivation leads to severe soil degradation problem.
High rainfall leading to intense leaching results in soils with poor base status.
Excessive moisture leading to water stagnation in valleys during (post) monsoon period limits the choice of crop.
Low temperature during post-monsoon period limits the cultivation of second arable crops. Monocropping is therefore commonly practiced in these regions.

Effect of climate change on the region

The metrological department suggests that the average temperature of Kashmir has gone up by 1.45 degrees Celsius over the last two decades, while in the southern plains the temperature rise is 2.32 degrees Celsius. Deficit in food production in Kashmir region has reached 40 per cent from 23 per cent in 1980-81. As more and more paddy land is changed into rain-fed orchards, Kashmir's current 40 per cent food grain deficit is likely to touch over 60 per cent in the coming 10 years if the current rate of change is taken into account.

Drying up rivers, vanishing glaciers and falling food production in Kashmir corroborate the direct predictions about the effects of climate change.

Rising temperature is changing the climate and the lives of the people in the villages of Tehri Garhwal. Vijay Jardhari has a vague idea that "greenhouse gas" means pollution. And, he probably contributes towards easing the effects of pollution by preserving the forest in his village. Yet, he bears the brunt of its impact every day. Jardhari can explain how the warming climate is changing the delicate ecology of the Himalayas better than many scientists.

For instance, the summer monsoon is acting up. Normally, the region gets rain in August and September. But erratic monsoons have affected both kharif (monsoon) and rabi (winter) crops. "The rains are never on time" when you need it, there is no sign of rain. And, when it should be dry, there is a downpour. This destroys the crops. Moreover, if it does not rain properly, the land becomes too dry for the rabi crop, so that suffers too,- says Jardhari. Further up the Himalayas, in Mustik Saund village near Uttarkashi, people express the same worries.

Hilly areas are more suitable for forestation than agriculture; growing farming activities are ruining the ecology of this region resulting in land erosion. The land is suitable to grow apples. Oak tree is also grown in such climate. People in Jardhargoan at present grow 40 different kinds of crops including vegetables, potatoes, herbs and medicinal plants. Crops fail due to the uncertainty of rains. The springs in the region are drying up making farming a highly risky profession.

2) Impact on the arid agro-ecological region

The hot and arid agro eco region covers southwestern parts of the states of Punjab and Haryana, western parts of Rajasthan, Kachchh peninsula and northern part of Kathiawar peninsula in Gujarat State. The area accounts to 31.9 m ha, representing 9.78 percent of the total geographical area of the country. The region is characterized by typical hot summer and cool winter (arid).

The mean annual precipitation is less than 400 mm. The area is under rainfed mono-cropping (traditional) agriculture. The resistant and short duration rainy season crops, such as pearl millet, "chari" (fodder), and pulses are grown in non-saline areas. The yields are low under average management practices. In areas favoured by availability of irrigation water, cotton, sugarcane, mustard, gram and wheat are grown.

The natural vegetation comprises sparse, sporadic tropical thorn forest. Recent statistics show that the forest area in the region is drastically reduced from 15 to almost 1 per cent.

Constraints

Erratic and scanty rainfall leading to high water deficit.
Soil salinity leading to frequent physiological droughts.
Acute drought at the time of grain formation
Nutrient imbalance, especially for N, P Zn and Fe.

Effect of climate change on the region

The 500 million persons who live in the world's desert regions can expect to find life increasingly unbearable as already high temperatures soar and the available water is used up or has turned salty, according to the United Nations Environment Programme report. It is not the physical growth of deserts but the rising water tables beneath irrigated soils that are leading to more salinisation - a phenomenon already taking place across large tracts of China, India, Pakistan and Australia. The Tarm river basin in China, it says, has lost more than 13,000 sq km of farmland to salinisation in a period of 30 years.

But the greatest threat to people and wildlife living anywhere near deserts is climate change, which is already having a greater impact on desert regions than elsewhere. The Dashti Kbir desert in Iran has seen a 16 per cent drop in rainfall in the past 25 years, the Kalahari a 12 per cent decline and Chile's Atacama desert an 8 per cent drop.

The Thar desert - which basks in sunshine for a yearly average of 320 days - has suddenly been transformed into a trough of death and destruction. An uninterrupted weeklong downpour in August caused flash floods, the worst in at least a century.

The unprecedented event not only caused extensive damage to life and property, it also rendered homeless over a million people in Jaisalmer and Barmer districts. More significantly, it shattered the rhythm of desert life for communities that had combated drought and water shortage all their life.

After the surprise flooding of Barmer and other arid parts of western Rajasthan, Scientists believe all this water will change not only the look of this desert region but also its ecology.

The floods have created at least three large lakes - in Kawas, Malwa and Uttarlai - all in Barmer district, and each covering 7-8 sq km. NGO field-workers involved in conservation and water harvesting estimate that there are more than 20 new water bodies in the Barmer-Jodhpur region. Several water channels or natural drains have also shown up after the flooding.

Floods are always bad for this region because when water falls on the desert, it mixes with the sand and makes water saline and makes it unfit to drink.

However, scientist and meteorological experts have different opinions. In short, the experts say, what happened in Barmer was nothing out of the ordinary. To call flooding in a drought-prone region as nothing unusual might be hard to swallow, but meteorologists say that one has to look at the bigger picture. According to Nityanand Singh of the Indian Institute of Tropical Meteorology, Pune, rainfall has been increasing in the Rajasthan desert since 1973, though marginally. What has also made a difference is the decreasing rain spells, not just in Rajasthan but in Punjab and Gujarat. As a result, the intensity of showers is greater.

Singh recalls that there were heavy floods in Jodhpur in 1979 and 1981. He says that given the trend of weather patterns, there could be floods in Rajasthan every third or fourth year.

While climate experts are divided on the phenomenon of industrial emission-induced global climate change, they are emphatic that one shouldn't rush to associate the Barmer floods as a sign of a major change in weather patterns in the near future.

Arid region with red soil and black soil

It comprises a part of the Deccan plateau that includes the districts of Bellary, SW parts of Bijapur and Raichur of Karnataka and Anantapur of Andhra Pradesh. The climate is characterized by hot and dry summer and mild winter. The rainfall is erratic and ranges from 400 to 500 mm. The yields under traditional agricultural practices are very low. Groundnut, sunflower, sugarcane and cotton are intensively grown under irrigated conditions wherever feasible.

Constraints

High runoff and erosion hazard during stormy cloud bursts.
Prolonged dry spells during crop growing period resulting in occasional crop failure.
Narrow range of workable soil moisture in Black soils
Subsoil sodicity affecting soil structure, drainage and oxygen availability, especially in subdominant black soils.
High subsoil density in red loamy soils limiting effective rooting depth.

3) Impact on the tropical wet agro-ecological region

This agro-ecoregion comprises Sahayadris, western coastal plains of Maharashtra, Karnataka and Kerala States, including Nilgiri hills of Tamil Nadu. The region occupies an area of 11.1 m ha, representing 3.6 per cent of the total geographical area of the country. The climate is characterized by hot and humid summer and warm winter.

The mean annual temperature varies between 25Â?C and 28Â?C. The agro-ecoregion comprises the group of islands of Andaman and Nicobar in the east and that of Lakshadweep in the west. The Lakshadweep islands receive 1600 mm rainfall representing humid climate, and the Andaman-Nicobar group of islands receive 3000 mm rainfall representing humid climate.

The natural vegetation comprises tropical rain (evergreen) and littoral and swamp forests. About 2/3 of the Andaman is under native forest and agriculture is confined only to specific areas around habitations, where the dominant crop grown is rice. In general, the land use is dominated by plantation crops, such as coconut, arecanut, oilpalm with or without intercultivation of pineapple, tapioca and pepper

In Lakshadweep, rice is mainly grown under lowland conditions. Coconut is the main plantation crop with high yield. Besides agriculture, marine fishery is an important means of subsistence for the people.

Constraints

Waterlogging, resulting from imperfect drainage conditions affects crop growth in the coastal plains western coasts.
Steep slopes, causing runoff, leads to severe soil erosion in western coasts.
Inundation of land area results in localised saline marshes in western coastal areas.
Degradation of the tropical rain-forest ecosystem leads to severe soil erosion hazard. With the clearing of rain forests, the ecosystem is disturbed resulting in severe soil erosion.
Inundation of coastal areas leads to saline marshes and consequently formation of acid sulphate soils in the two islands.
Gradual increase in areas under mangroves suggests increase in degradation of the coastal areas of the islands.

India's climate is dominated by the southwest monsoon. Heavier rainfall during summer could increase flooding, but the monsoon may fail with the increasing frequency and intensity of the El Nino phenomenon.

With over 6,500 kilometres of low-lying, densely populated land, millions of Indians are at risk from sea-level rise.

4) Impact on the tropical wet and dry agro-ecological region

We are taking Eastern coastal areas separately from the other tropical wet and dry areas because this area is highly influenced by climate change.

This agro-ecoregion comprises the south-eastern coastal plain, extending from Kanyakumari to Gangetic Delta. This region covers an area of 8.5 m ha, representing 2.6 per cent of the total geographical area of the country.

The Eastern Coast extending from anyakumari to Gangetic delta experiences wide range of climate conditions. The coastal parts between Kanyakumari and south of Thanjavur (Tamil Nadu) and between north of Chennai and west Godavari (Andhra Pradesh) receive the rainfall of 900 to 1100 mm.

Both rainfed and irrigated agriculture are practiced in the region. The lead crop cultivated in the area, both in kharif and rabi season, is rice. Coconut is a dominant plantation crop of the region. In some parts, pulses, such as blackgram and lentil, and oilseed crops, such as sunflower and groundnut are cultivated after rice (on residual moisture). Besides agriculture, raising of coastal and brackish water fisheries are important economic activities of the coastal people.

Constraints

Imperfect to poor drainage conditions and limiting oxygen availability adversely affect crop yield.
Soil salinity (and sodicity at places) resulting from poor drainage conditions adversely affect crop production.

The area is prone to cyclone during monsoon and retreating monsoon periods.

Impact of climate change in this region

The area is highly vulnerable in terms of climate. Maldives will go completely under the ocean due to global warming. Global warming has been observed on the Orissa coast for the past 15 years. A big tidal wave hit the coast in the Satabhaya area of Kendrapara district. It swept away homes and inundated farmland. Tidal waves like this one have been a regular phenomenon in the area. In the past 15 years, the sea has come inside the land by 2.5 kilometers. And as many as 600 families are leading a precarious existence in the Satabhaya and Kanhupur areas due to this phenomenon.

The speed with which the sea is capturing land has forced the locals to spend sleepless nights fearing for their lives and properties. The local business community which includes hoteliers and those involved in the travel trade also apprehend that the town would soon lose its charm as a major tourism and religious destination if the government did not step in to address the problem. The sea erosion in Puri has been taking place slowly since the last four to five years. However, the situation worsened last month when a portion of the marine drive was washed away by tidal wave.

A classic example is the Sunderbans area. Life on the remote inhabited islands of the Indian Sundarbans is far removed from the world of glitzy shopping malls, flyovers, jet-set- ting middle classes and highflying life that India Shining has come to be exemplified by. In fact, the basic amenities of life are yet to be available to the inhabitants of these islands. Yet, poorest on these islands are paying the price of global warming and rising sea levels as more than 10,000 environmental refugees struggle for survival here.

Bengal's watery grave is a tragic story of Nasim Aktar from Malda district of north Bengal written by Nilanjan Dutta. It was published in The Times of India dated 22/06/2006. It is a story of a family that was affected by land erosion. There are 6, 00,000 people displaced in the two districts. There are families that have been displaced 16 times.

Other areas under tropical dry and wet regions

The agro-ecoregion with hot, subhumid climate and red and black soils covers part of Malwa plateau and Bundelkhand uplands including Baghelkhand plateau, Narmada valley, Vindhyan scarplands and northern fringe of Maharashtra plateau, and some districts of Madhya Pradesh. It covers an area of 22.3 m ha representing 5.8 per cent of the total geographic area of the country.

It also constitutes Chhotanagpur Plateau of Bihar, western parts of West Bengal, Eastern Ghats (Dandakaranya and Garhjat hills) of Orissa and Bastar Region of Chhattisgarh. It occupies an area of 26.8 m ha, representing 8.2 per cent of the total geographical area of the country. The climate of the region is characterized by hot summers and cool winters. The area receives an annual rainfall of 1000-1600 mm which covers about 80 per cent of the PET leaving deficit of 500 to 700 mm of water per year.

Rainfed farming is the traditional practice with cultivation of rice, pulses (moong, blackgram and pigeonpea) and groundnut. In rabi season, rice (at places) and wheat are cultivated mostly under irrigated condition. The natural vegetation comprises tropical dry and moist deciduous forests. However, rich farmers grow rice, wheat and gram and, at places, cotton using irrigation facilities.

Constraints

The soils are susceptible to severe erosion hazard.
Seasonal droughtiness limits optimum crop yields.
Cracking clayey soils having narrow workable moisture conditions.
Dry tillage and inter-tillage practices are difficult to perform.
Risk of inundation of the cropped areas during rainy season and risk of acute droughtinessKharif season leading to crop failure at places.
Soil loss due to heavy runoff during rainy season resulting in stagnation of water and poor germination.
Deficiency of N, P and Zn resulting in nutrient imbalances.

Due to prolonged dry spells in Orissa celebrates Nuakhai - a festival that marks a good harvest, but climate change may put a halt on such celebrations. Agriculture in the state largely depends on nature and climate change is going to hit it badly. Climate change has been affecting the state from the last couple of years. In Orissa, rainfall has become more erratic and less compatible to crop schedules. According to reports only seven of the last 25 years have normal or more than normal rainfall. The rest have been deficient rainfall years. Disasters have spread to new areas. Floods have wreaked havoc for years in the state, drought prone districts like Balangir, Kalahandi, Koraput, Bargarh and Jharsuguda are facing recurrent flash flood furies while heat waves have begun hitting coastal regions.

5) Impact on the humid sub-tropical agro-ecological region

The agro-climate of the region is characterized by warm/hot summer and cool winter. The agro-ecoregion with hot, subhumid (dry) climate and alluvium-derived soils covers a part of the northern Indo-Gangetic plain, including plains of the western Himalayas. It also comprises eastern plateau, Chhattisgarh region and southwest highlands of Bihar State.

Injudicious use of irrigation water may lead to waterlogging and salinity hazards. The region, comprising the plains of the Brahmaputra and the Ganga rivers, covers parts of the states of Assam and West Bengal. The climate of the area is characterized by hot summer and mild to moderately cool winter.

Traditionally the rainfed and irrigated agriculture is common. The crops grown are rice, maize, barley, pigeonpea and jute in kharif season. The soils are susceptible to severe water erosion hazard. There is partial water logging in early stages of crop growth and seasonal droughtiness during advance stage crop growth. There is Deficiency in N, P and micronutrients, such as Zn and B, causing nutrient imbalances.

The agro-ecoregion, comprising eastern plains covers north-eastern Uttar Pradesh and Northern Bihar including foothills of Central Himalayas. Rainfed agriculture with cultivation of rice, maize, pigeonpea, moong are common in kharif season. The important cash crops such as sugarcane, tobacco, chillies, turmeric, coriander and potato are usually grown with supplemental irrigation. The natural vegetation comprises tropical moist deciduous and dry deciduous forests. Flooding and imperfect drainage conditions limit soil aeration. Salinity and/or sodicity, occurring in patches, affect crop yields.

The north-eastern hills (Purvanchal) agro-ecoregion comprises hilly States of Nagaland, Meghalaya, Manipur, Mizoram and southern Tripura. Jhum cultivation is the traditional farming. Rice is the dominant crop grown in valleys and on hill terraces. Millets, maize and potatoes are cultivated on terraces at higher altitudes, while rice and jute are grown in small under rainfed condition. Hill terraces are also used for plantation crops, such as, tea, coffee, rubber and horticultural crops, like oranges, pineapple, etc. The natural vegetation comprises wet evergreen and tropical moist deciduous forests. Deforestation and shifting cultivation result in severe soil erosion hazard. Excessive rainfall leading to leaching results in depletion of nutrients rendering soil's poor in base status. Low temperature in post-rainy period limits the introduction of a wide variety of crops. Small to marginal land holdings limit the introduction of modern implements.

The change in sowing season due to temperature variations is impacting the wheat yield in Haryana, one of the key wheat producing states of India.

A paper authored by Dr J C Katyal, V-C of Chaudhari Charan Singh Haryana Agricultural University, Hisar, says that the rise of maximum temperatures during February and March over the past seven years coincides with pre- and post-grain formation stages and has had a negative impact on wheat yield. Katyal notes that "this challenges the very sustainability of food self-sufficiency reached in the early nineties"

6) Impact on the semi-arid agro-ecological region

The semi arid agro-ecological region constitutes parts of Gujarat, northern plains and central highlands (Malwa), and the Deccan plateau.

The climate of the region varies. Some regions are characterized by hot and dry summer and cool winter whereas some regions are characterized by hot and wet summer and dry winter. The main crops which are grown in this region are millets, wheat and pulses. Rice and sugarcane is grown under irrigation facilities.

In some parts of central highlands, like Bundelkhand, less than 25 per cent of the net cropped area is under irrigation, while the rest is under rainfed agriculture. In Deccan plateau, comprising most of the central and western parts of Maharashtra, northern parts of Karnataka and western parts of Andhra Pradesh the traditional practice is rainfed agriculture.

Constraints

Over exploitation of groundwater in irrigated areas, resulting in lowering of groundwater table.
At places, imperfect drainage conditions leading to spread of surface and subsurface soil salinity and/or sodicity.
Imperfect drainage limits optimum root ramification and oxygen availability in low-lying areas.
Salinity and alkalinity hazards under irrigated agriculture.
Severe salinity and seasonal inundation by sea water in the Kathiawar coast resulting in crop failure.
Deficiency of N, P and Zn leads to nutrient imbalance.
High runoff during rainy season leads to severe soil and nutrient loss both in the red and black soil areas.

Impact of climate change in this region

Results of an experiment carried out by the Department of Agricultural Meteorology, B A College of Agriculture, Anand Agricultural University says that global warming and greenhouse effect will have an impact on the yield of wheat and maize in the state.
The arid and semi-arid regions are set to suffer further water shortages, while tropical, temperate and boreal Asia are likely to experience increased flooding.

References