The climate change is likely to exert adverse impacts on productive resources and ultimately on agricultural productivity of the country, said a resource study on the subject. The study said there is now consensus among the scientific community that Global Warming is occurring due to anthropogenic activities mainly the emission of Greenhouse Gases by burning of fossil fuel, deforestation and land use change.
Global warming, or climate change, has both positive and negative effects, but the negative impacts outweigh the positive impacts in Pakistan. It is a challenge for planners, policy makers, researchers and thinker alike.
The major climatic stresses that will exert pressure on agriculture are; increasing temperatures in arable areas, changes in rainfall patterns (becoming irregular and severe), increased variability of monsoon, changes in availability of irrigation water, severe water-stressed conditions in Arid areas, extreme events; such as floods, droughts, heat waves, cold waves and cyclone etc.
The most vulnerable communities to climate change in Pakistan are small land holders that form more than 80% of the total forming community. The farmers in arid and hyper-arid regions and those living in mountainous and coastal areas are more exposed to the climate change and extreme events.
The impact of climate change on agriculture include; the shortening of Growing Season Length (GSL), heat stress at critical reproductive stages and increased water requirements of crops. The wheat yields in agro-climatic regions will show decline trend, except in mountainous areas where wheat yields are showing an increasing trend mainly because the mountainous areas are still short of temperatures.
The climate change will also cause loss of biodiversity and shifting of forest areas northwards (to cooler places). Expected precipitation will have positive impact on the forests in the northern watersheds. Frequency of forest fires will increase due to increased heat and erratic rainfall causing damage to regeneration and plantation areas. Species composition may change with the changed ecology.
There will be enhanced risk of proliferation of pests and diseases under climate change. Some insect pests and diseases proliferate under high rainfall conditions and some thrive under warm and moist conditions while others under dry conditions.
The climate change will lead to irrigation water shortage due to changes in river flows as a result of glacial melt. Erratic and uncertain pattern of rainfall will affect arid and hyper-arid areas. Increased evaporate-transportation as a result of high temperatures will increase water demand of crops.
The climate change will also affect glaciers and the glaciers and all over the world are receding fast due to global warming. Shrinking glaciers have serious implications for sustainable water supply. Glacial melt in Himalayas is projected to increase flooding within next two to three decades. This will be followed by deceased river flows as the glaciers recede. The formation of Glacial Lakes and their outburst has also been threatening the lives and livelihood of local population.
The climate change will also impact livestock productivity especially due to high temperatures. These include physiological stress on animals, productivity losses (milk and meat), stress on conception and reproduction; climate related disease epidemics, reduced productivity of fodder crops, decreased quality and palatability of forages and increased water requirements of animals and fodder crops.
At higher elevations, fisheries are likely to be adversely affected by lower availability of oxygen due to a rise in surface air temperatures. In plains, the timing and amount of precipitation could affect the migration of fish species from the river to the floodplains for spawning, dispersal, and growth. Future changes in oceans currents, sea water temperature, wind speed and direction, and predator response to climate change will substantially alter fish breeding habits, food supply for fish and ultimately the abundance of fish populations. Areas under mangrove forests which are the breeding ground/hatching places for fish are decreasing rapidly due to climate change.
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