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Skating on thinning ice PDF Print E-mail
Thursday, 28 January 2021 08:54
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The shrinking of the world’s ice is now following the worst-case climate change scenario outlined by the Intergovernmental Panel on Climate Change. A study by researchers at the University of Leeds has found that the world has lost a whopping 28 trillion tonnes of ice between 1994 and 2017—for a perspective that is over 1.2 trillion tonnes of ice lost per year over a little more than two decades, while the ice-loss figure was 800 billion tonnes till then.

The study, published in the journal The Cryosphere, is based on satellite data, on-site data and numerical models, and finds that the bulk of the loss can be attributed to climate change. One corollary from this would be that the rise in ice-volumes melting every year signal an acceleration of climate change due to anthropogenic factors. With time having almost run out on any meaningful reversal of climate change, the focus now has to be to shift the planet to a lower-warming trajectory than it is currently on.

Given how ice-melts exacerbate climate change—let alone the consequences of viruses and microflora that had been lying dormant in the ice for many millennia getting released, with possible pathogenic effect—the problem needs urgent attention if countries are to prepare for mitigation of impact.

The problem of ice-melt is two-fold: loss of ice from land and loss of sea-ice. Thanks to rising air temperatures as greenhouse gas (GHG) emissions rise, mountain glaciers, from those in the Alps to the Andes to the Himalayas, are shrinking. The study claims glaciers have lost nearly 10 trillion tonnes of ice since the 1960s, with the melt having shot up sharply in recent years—nearly 6 trillion tonnes have been lost since the 1990s.

This is deeply worrying given ice on land constitutes just 1% of global ice, and yet accounts for a quarter of the planet’s ice-loss since the 1990s. With populations across continents dependent on mountain glaciers for freshwater (many of India’s perennial rivers of the north have their origins in Himalayan glaciers), this loss has been rather stark over the past few years and has generated concern amongst policymakers.

Bear in mind, glaciers suffer a double whammy as warming oceans are multiplying the ice-loss from marine-terminating glaciers, or glaciers that end in the ocean—warm currents are contributing a ‘bottom-up’ melting of glaciers. This feeds into a vicious circle, given melting glaciers pour more water into the oceans, causing the sea-ice to shrink further. Melting sea-ice, in turn, exposes the dark water underneath, which, unlike ice that reflects a lot of the heat it faces, absorbs this heat. Combined losses of ice have led to a 1.3-inch rise in sea levels.

For India, the stakes from loss of global ice are high—melting mountain glaciers mean threatened freshwater sources in the large tracts of the country, which has a devastating impact on nearly everything, from food security (because of the impact on agriculture) to health and hygiene. The other major threat is the impact of rising sea-levels on India’s 7,500-km long coast that houses some of the country’s most important cities, including financial capital Mumbai and the southern metropolis, Chennai; Mumbai alone could see significant parts inundated by 2050, affecting many millions.

A study published in Scientific Reports in 2020 projects the global population exposed to inundation and episodic coastal flooding by 2100 at 300 million—indeed, nearly half of the area vulnerable to coastal flooding is vulnerable because of regional sea-level rise—and the value of the global assets threatened by these episodes at $6-9 trillion.

Read with the new University of Leeds report, time is running out for nations with significant coastal lengths to prepare for rising sea levels. While the ministry of Earth sciences launched a multi-year study in 2012-13 to assess the threat and develop specific regional models, it is already time that action to protect populations currently living on the coast and dependent on the sea for livelihoods is mounted.

 
 

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