Global Warming & Freshwater Supplies

Pity the frog living here
Freshwater Scarcity

Yesterday Daily Express carried two articles titled “Malaysia running out of clean water” and “Danger of Global Scarcity”. Only 2.5% of the world’s water is freshwater, and out of this only 1% is actually available for ecosystems and humankind; the rest is frozen in the polar regions, glaciers, and high mountains as well as in underground water basins. And, as we all know, this 1% is not all potable due to pollution and life-threatening conditions.

With global warming and the consequent melting of the freshwater polar caps and glaciers, it may seem counterintuitive to say that this world climate change will exacerbate the problem of scarcity of freshwater supplies in many countries. A United Nations Environment Programme report says that by 2050, scarcity would have jumped from 3% in 1995 to 18% (see pie chart above).

Why is this so? In a nutshell, this is because in general, global warming accelerates the hydrological cycle. Warmer air causes more water to evaporate. A warmer atmosphere can hold more water vapor, so more water is available to fall back to Earth when it rains or snows. As a result, extreme precipitation events should become more frequent and intense. Rainfall patterns will continue to change around the world. Computer models project that, as warming progresses, the temperate regions as well as Southeast Asia will receive more precipitation. Ah, so you say, we expect to have more water then, not less. Not so fast: because of the changes in the hydrological regime, when it rains, it will really rain (and cause severe floods, like our friends in Kinabatangan, Kota Belud and Kota Marudu only know too well) but the droughts will be longer. You know, like 4 months already this year in Sabah. In addition, the rise of the sea level will impact on our coastal freshwater supplies by saltwater intrusion.

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