Social Implications of Climate Change for

Coastal Areas of Pakistan

Paper Presented at

Euro-Asian Research and Training in

Climate Change Management

2007

Dr. Mirza Arshad Ali Beg

Former Director General PCSIR

136-C Rafahe Aam Housing Society, Malir Halt, Karachi-75210

e-mail: arshadalibeg@gmail.com

The impact of Climate Change having different consequences within and between countries has indeed been noticed in the context of diversity in the ecosystems of Pakistan ^{(Mirza Arshad Ali Beg, Comments on Pakistan National Communication on Implementation of UNFCCC, May 2001)}. The situation current in 2001 indicated that Pakistan is faced with extremes of climate variations resulting from natural as well as man made modifications. The aftermath of Cyclone 02A, which landed on the low lying coastal area of Badin in May 1999 and the floods in the same area in 2003, were a preview of the impending disaster due to climate change.

Climates dominated by monsoons experience the most pronounced seasonal wind shifts. In South Asia, the rainy season, typically beginning in June, is preceded by nearly two months of scorching temperatures, cooled only with the commencement of the summer rains brought by the southwesterlies. January is the peak of the dry season, which is marked by cool, dry northeasterly flow over most of the region.

The monsoon climates are especially vulnerable to disruptions in global weather, which have, in any given year led to drought, flooding, or both. The over 150 years of data and assessment of driving forces behind the southwest monsoon circulation has resulted in a better understanding of weather extremes experienced throughout the tropics, and their subsequent impact on ecological balance governing aquatic ecology. These data conclusively indicate that no other region outside the monsoon belt is as much vulnerable to the extremes of wetness and dryness as the tropical monsoon belt.

Changes in Ecological Balance & Water Resource Depletion

Man made interventions have caused water scarcity in the region that includes Pakistan. The scarcity is likely to continue for the next few decades, mainly because of inadequate management of the precious resource. This has created a mismatch between availability from surface run off and extensive water use. Withdrawal from all sources viz. rivers, lakes, and reservoirs, and mining of underground aquifers at an unprecedented rate had increased not only in Pakistan but also in Asia, in general, by almost 300% between 1950 and 1995, and may have increased further if the availability was not a constraint.

A mismatch between availability of water and its extensive use that has increased by almost 250% during the last 50 years in Pakistan, has resulted in withdrawal from all sources viz. rivers, canals, wells, tubewells, karezes and springs^{(Economic Survey 1999-2000, Government of Pakistan, Finance Division, Economic Advisor’s Wing, Islamabad)}. This type of modification in the ecosystem has increased aridity in the region and has instigated losses of habitat, vegetative cover, biomass and biodiversity^{(The Pakistan National Conservation Strategy, Environment & Urban Affairs Division, GoP, and IUCN)}. Construction of large dams, diversion of river flow into an intricate irrigation system and over harvesting of groundwater resources constitutes the greatest intervention of ecosystem of the region, and a large interference in the water cycle by increasing the losses due to evaporation and seepages and the consequent increased availability of water vapour, a greenhouse gas in the air.

The process of augmented withdrawal during the decade after 1995 proceeded to the extent that Pakistan is relegated to water stressed country from the status of water surplus country. It is estimated that almost 10% of the agricultural food production is now dependent on mined groundwater. Water tables that were falling at a rate of a metre a year have been going down at a much rapid rate. In the Quetta valley, for example it has fallen by 30 metre during the last 20 years. A similar situation is being faced in China, India, Mexico and Yemen, the other countries falling in the same belt.

Loss of storage in the aquifers and their mining already indicates that availability of water in Pakistan has decreased and is less likely to be reversed since recharging of the aquifer takes several hundred years, if left to the natural process of surface water infiltration. Fluctuations in water table are vulnerable to weather changes e.g. changes in temperature, humidity and rainfall, besides soil permeability. These changes affect the rate of evaporation and evapotranspiration and also the sub-soil flow. Aridity causes increased evaporation, which in certain cases is in excess of 3 cusecs per square mile in certain worse areas. Evaporation from soil surface is related to the depth of groundwater. It is very high, ranging up to 50% of the surface water evaporation for a groundwater depth of 2 to 3 ft; 33 to 55% for a depth of 5 ft and 20% for a depth of 10 ft.