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RISING SEA LEVELS - A GLOBAL CONCERN

There are many consequences of climate change, and one that is likely to have a profound impact on human civilisation is rising sea level. We know from various studies that sea levels changed little over the 2000 years to 1900. Since then, sea levels have begun to rise at and accelerating rate in response to increasing emissions of greenhouse gases. Satellite data indicate that since 1992 the rate of sea level rise has reached 3 mm per year, which is a rate subtsantially greater than the average rise over several thousand years.

What are the casues of sea level rise? Firstly, there is expansion of sea water as the oceans get warmer, which accounts for about a third of the rise. Secondly, and more importantly, is the melting of glaciers and ice sheets. In fact, the Intergovernmental Panel on Climate Change (IPCC) predicts that sea levels will rise by nearly a metre by 2100, with contributions from glaciers and ice caps (0.2 m), the Greenland Ice Sheet (0.15 m) and the Antarctic Ice Sheet (0.3 m). As a glaciologist, I find the visual evidence deeply worrying: mountain glaciers are receding and thinning at an alarming rate, the Greenland Ice Sheet is discharging more ice into the ocean than ever before and melting over a much wider area, and the ice shelves (floating masses of ice) in Antarctica are collapsing thereby allowing inland ice to discharge more rapidly into the sea. Yes, there are exceptions to the decline of ice masses, but these are few and far between. The world's ice masses contain enough water to raise sea levels by about 70 metres in total, and many are not sustainable under the present climate. The consequences of melting are drastic for low-lying communities around our coasts.

A rich country like ours can undertake remediation measures to prevent coastal flooding (at great expense to the taxpayer), but the impact on poor communities in the developing world, such as Bangladesh. will result in tens of millions of people being displaced. Displacements on this scale will put the current refugee crisis in the shade. The bottom line is that our addiction to fossil fuel has caused this warming, but those who will suffer most are the poor in other parts of the world. The need to switch to renewable energy has never been greater.

 

Kesmail September 2016

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