Offshore Miami? Climate risk views from UCL
Prof Bill McGuire is Professor Emeritus in Geophysical & Climate Hazards at University College London (UCL). When we asked him about rising sea levels, here's what he told us...
In the 22 years to 2015, global sea level rose by 7cm. If it carries on like this, then by 2100 it would be reasonable to expect sea level to be around 30cm higher than it is now; enough to want to keep an eye on, but not enough to lose sleep over. The past, however, rarely provides an accurate guide to the future, and certainly not where climate change is concerned. Increasingly rapid melting of the Greenland and Antarctic ice sheets, driven by big hikes in air temperature and warmer ocean waters is dumping vast quantities of freshwater into the oceans; in excess of 250 billion tonnes a year from the Greenland Ice Sheet alone – that's more than 110 million Olympic swimming pools to you and me.
Notwithstanding the plateauing out of global greenhouse gas emissions in the last few years – at a mere 32 billion tonnes of carbon dioxide in 2016 – global temperatures and the melting rates of the polar ice sheets are heading in only one direction; upwards. The consequence is that global sea level will start to climb more rapidly as time goes by. The key question is – how quickly will this happen? Ominously, for anyone living in a coastal town or city, the worst-case scenario for end-century sea level rise keeps getting worse. The received wisdom, based on earlier IPCC (Intergovernmental Panel on Climate Change) reports, is that sea level could be a metre higher by 2100, but that there was also a good chance that the rise would be smaller. But things have now moved on. In 2014, researchers from the University of Copenhagen's Niels Bohr Institute proposed a worst-case rise of 1.8m by the century's end. Jump forward three years to this spring and the situation has changed again, with the worst-case rise for 2100 climbing to an astonishing 3m.
It doesn't take much imagination to appreciate the potentially catastrophic impact such a rise would have on the exposure to flooding and permanent inundation of all coastal communities, particularly given the short run-up time. If this worst case actually plays out, sea levels could be a couple of metres higher than they are now in little more than half a century; far too quickly to allow serious countermeasures to put in place. It is worth noting that just a 1m rise in sea level would see the level of flood protection provided by the Thames Flood Barrier fall from 1 in 1,000 years to 1 in 10. In other words, the likelihood of an annual flood would rise from 0.1 percent to 10 percent. Perhaps the most dramatic picture of what a 3m sea level rise might mean, however, is provided by the fact that it would leave the city of Miami – or what's left of it - floundering more than 40km offshore.
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Want to know more? UCL runs a unique postgraduate certificate course called 'Natural Hazards for Insurers' and it's open for applications. You can contact Prof McGuire directly for more information - email@example.com