Home Contact us Gallery Site Map Resource Centre Search About us People News Publications Education & Training Events Publications | Education and Training | Current & Recent Projects | Events | Research Opportunities

Download issue (1.37MB PDF) Cover Page Executive Summary 1.Climate Change: a primer 2.What is dangerous climate change? 3.1.Causes of sea-level rise 3.2.Rates of sea-level rise in history 3.3.Ice sheet melting and catastrophic sea-level rise 3.3a.The Greenland Ice Sheet 3.3b.The West Antarctic Ice Sheet 3.3c.Future prospects for coastal environments 4.Gulf Stream shutdown 5.Conclusions 6.Sources and Further Reading

Issues in Risk Science Dangerous Climate Change: rising sea-levels and ocean circulation changes - Professor Bill McGuire 3.3c. Future prospects for coastal environments In 1990, it was estimated that around 1.2 billion people (~ 23 percent of the global population) lived within the near coastal zone (within 100 m vertically and 100 km horizontally of the coast). This includes more than 250 million inhabitants of 14 of the world’s megacities (population = 10 million). By 2015, more than 340 million people will live in 21 megacities, 18 of which will occupy coastal locations. The highest population densities are encountered below the 20 m elevation, and are therefore at greatest risk from storm surges, tsunamis and sea-level rise. Depending on which population growth scenario is used, the near-coastal population could rise as high as 5.2 billion by the 2080s. If the current 3 mm annual rate of sea-level rise continues, global average sea-levels by this time would be 25 cm higher than they are now. This is highly unlikely, however, and some acceleration is near certain. A rise of 1 m or more this century is now a possibility, with irreversible deglaciation of Greenland and/or a future collapse of the WAIS committing to an eventual rise of > 10 m within a thousand years and possibly much sooner. While mitigation measures, in the form of reduced greenhouse gas emissions, could reduce the risk of such dramatic rises, they may have to be enacted in the next few decades if we are to prevent a long-term commitment to serious sea-level rise. Such a situation could result in between 300 million and 1 billion people being affected by rising sea-levels within 500 years; these figures ultimately rising to between 800 million and 2.4 billion people. In the shorter term, a ~ 1 m rise by the end of the century would require massive programmes of sea-defence modification and new-build, alongside policies of managed retreat and relocation. In the UK, a 1m rise would require the Thames barrier to be raised for perhaps 300 days a year, which would effectively close the Port of London. Elsewhere, the Maldives and many small ocean states would no longer be able safely to sustain populations, while large areas of places such as southern Florida and Bangladesh would be inundated without major protection initiatives. Major river deltas, such as the Bengal (Bangladesh), Mekong (Vietnam), Nile (Egypt), Yangtze (China) and Mississippi (US), many of which are sinking due to water and oil extraction or the upstream damming of sediment, are particularly at risk.