Friday, September 19, 2008
By Jawwad Rizvi

LAHORE

THE Pakistan government has so far not initiated research to assess the impact of global warming on agriculture – the backbone of economy.

The government machinery is silent on this issue. No government researcher is working to determine the impact of global warming on agriculture sector.

A senior official of the Food, Agriculture and Livestock Ministry said that in Pakistan, the basic problems of agriculture were yet to be addressed and global warming was not a visible problem.

Pakistani farmers were facing problems of unavailability of water, quality seeds, fertilisers and other inputs which were crucial and should be addressed first, he said. He said farmers and the government machinery will look into the issue of global warming and its impact on agriculture sector once basic issues were addressed.

Progressive as well as traditional farmers are also almost completely unaware. They say timely availability of agriculture inputs is the major problems besides water shortage.

Global warming is caused by the release of ‘greenhouse’ gases into the atmosphere. These gases accumulate in the atmosphere, resulting in warming of the atmosphere.

Change in climate impacts crop patterns, water availability and to some extent productivity of crops as well. Hamid Malhi, a progressive farmer said weather pattern has slightly changed due to global warming. He said framers only know that water availability was now unpredictable and that it was badly affecting crop production. “We observed a slight change in monsoon pattern because of climate change,” he said.

Glaciers are melting due to global warming and if this goes on than agriculture productivity in the country would be affected, he said. He said so far no quantum decline or increase in crop productivity and change in crop pattern had been witnessed.

As no one has conducted research on the issue, predictions about the effects of climate change are not very reliable. Agriculture is one sector that is important to consider in terms of climate change. This sector both contributes to climate change, as well as is be affected by the changing climate.

According to world research, agriculture accounts for approximately one-fifth of the annual increase in anthropogenic (man-made) greenhouse gas emissions. The sector contributes to global warming through the emission of Carbon Dioxide, Methane and Nitrous Oxide gases. The greenhouse gases are so called because although they allow light reaching the earth, they block the heat (infra-red radiation) from escaping the atmosphere, thus trapping the heat as in a ‘greenhouse’. CH4 has the highest global warming potential that is about 300 times the potential of CO2, and about 20 times that of N2O. The main sources of these gases are flooded rice fields, nitrogen fertilisers, improper soil management, land conversion, biomass burning, and livestock production and associated manure management. The livestock industry alone is said to account for between five to 10 percent of the overall contribution to global warming.

Researchers working across the globe have found that the effects of climate change on agriculture will differ across the world.

They believe that a variety of effects were likely to occur due to climate change. Changes in temperature as well as changes in rainfall patterns and the increase in CO2 levels projected to accompany climate change will have important effects on global agriculture, especially in the tropical regions.

It is expected that crop productivity will alter due to these changes in climate, and due to weather events and changes in patterns of pests and diseases. Land areas suitable for cultivation of key staple crops could undergo geographic shifts in response to climate change.

Modelling climate change impacts on regional food supplies is difficult for a number of reasons, including uncertainties in regional climate change predictions; the fact that our understanding of certain agricultural processes, in particular the ‘fertilization’ response of different crops to increased levels of atmospheric CO2, and the likelihood of altered patterns and distributions of plant diseases, weeds, insects and pests, remains incomplete; and uncertainty regarding the potential for adaptation of agricultural practices.

The global aggregate effect of climate change on agricultural production is likely to be small to moderate. However, regional impacts could be significant. Crop yields and changes in productivity will vary considerably across regions. These regional variations in gains and losses will probably result in a slight overall decrease in world cereal grain productivity.

Vulnerability to climate change depends not only on physical and biological responses but also on socioeconomic characteristics. Low-income populations dependent on isolated agricultural systems are particularly vulnerable to hunger and severe hardship. In these areas where populations are already barely food-sufficient, even the slightest decline in yields could be very harmful.

Impacts on rice yields in South and Southeast Asia are likely to vary greatly. Several major studies have been conducted for countries in East Asia, including China (mainland and Taiwan), North and South Korea, and Japan (IPCC 1996).

Possible climatic impacts span a wide range depending on the climate scenario, geographic scope, and study. While large changes were predicted for China, the studies conclude that to a certain extent, warming would be beneficial, with yield increasing due to diversification of cropping systems. Studies for Japan have shown that positive effects of CO2 on rice yields would generally more than offset any negative climatic effects.

Climate change could influence food production adversely due to geographical shifts and yield changes in agriculture, reduction in the quantity of water available for irrigation, and loss of land through sea level rise and associated salinisation.

Geographic limits and yields of different crops may be altered by changes in precipitation, temperature, cloud cover and soil moisture as well as increases in CO2 concentrations. High temperatures and diminished rainfall could reduce soil moisture in many areas, particularly in some tropical and mid-continental regions, reducing the water available for irrigation and impairing crop growth in non-irrigated regions.

Changes in soil, for example, the loss of soil organic matter, leaching of soil nutrients, and salinisation and erosion are a likely consequence of climate change for some soils in some climatic zones.

The risk of losses due to weeds, insects and diseases is likely to increase. The summer monsoon is predicted to become stronger and move north-westward. However, this increased rain could be beneficial to some areas.

In addition to changes in temperature and rainfall, changes in the frequency of extreme climatic events could be damaging and costly to agriculture.

While increases in temperature, changes in soil moisture, and shifts in patterns of plant pests and diseases, could lead to decreases in agriculture productivity, CO2 fertilisation could lead to some increase in agricultural productivity. Atmospheric CO2 levels are expected to have a positive effect on some plants, increasing their growth rate, and cut transpiration rates. Crop plants may also be able to use water more efficiently under higher CO2 levels.

Plants can be classified as C3, C4 or CAM, depending on the photosynthetic pathways they employ. C3 plants, including most trees and agricultural plants such as rice, wheat, soybeans, potatoes and vegetables, are likely to benefit from extra CO2.

The results of a large number of experiments have confirmed that elevated CO2 concentrations generally have beneficial effect on most crops.

C4 plants are mainly of tropical origin and include grasses and agriculturally important crops such as maize, sorghum, millet and sugarcane. The C4 plants are expected to benefit less from increases in CO2. CAM plants are a variant of C4 plants, and these plants are not likely to be affected.

Climate change could affect both livestock itself and dairy production. The pattern of animal husbandry may be affected by alterations in climate, cropping patterns, as well as ranges of disease vectors. In warm regions, higher temperatures would likely result in a decline in dairy production, reduced animal weight gain and reproduction, and lower feed-conversion efficiency. More mixed impacts are predicted for cooler regions. If the length and intensity of cold periods in temperate areas are reduced by warming, feed requirements may be reduced, survival of young animals enhanced and energy costs for heating of animal quarters reduced.

In general, intensely managed livestock systems have more potential for adaptation than mixed livestock-cropping systems. Adaptation may be more problematic in pastoral systems where production is very sensitive to climate change, technology changes introduce new risks, and the rate of technology adoption is slow. Livestock production may also be affected by potential changes in grain prices brought on by changing yields in some areas, or by changes in rangeland and pasture productivity. For developing countries, livestock are better able to survive severe weather events such as drought than are crops, and therefore a better option in terms of income protection and food security.

In the future, population growth without significant improvements in yield rates will mean more land must be used for rice cultivation and other crop production, and an increase in the number of farm animals. These factors will lead to an increase in CH4 and other greenhouse gases released to the atmosphere.

The regional increases and decreases associated with climate change are not expected to result in large changes in food production over the next century on a global scale. Therefore, impacts on regional and local food supplies in some low latitude regions could amount to large percentage changes in current production. Climate change may impose significant costs for these areas. In addition, warming beyond that reflected in current studies may impose greater costs in terms of total food supply.

Projections form most economic studies show substantial economic losses as temperature increases beyond the equivalent of a CO2 doubling. This reinforces the need to determine the magnitude of global warming which may accompany the CO2 build-up currently underway in the atmosphere.

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