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For many, sea level rise is one of the first things to come to mind when thinking of climate change. Cities rendered uninhabitable thanks to permanent flooding can be easier to envision than a global food shortage or the spread of insects and diseases beyond their current parts of the earth. Such cities may also be a reality sooner than previously thought.
At the current rate of global emissions, the earth’s sea level could rise as much as 6.6 feet by 2100. This number, which is higher than previous estimates, would render major coastal cities including Shanghai and New York uninhabitable unless they switched to a futuristic floating cities model. Sea level rise this high would force a whopping 187 million people to relocate, certainly overwhelming and destabilizing the world’s many areas already battling the effects of overpopulation.
The new 6.6 feet figure comes from a study published May 20th in the Proceedings of the National Academy of Sciences of the United States of America (PNAS). This study points to the accelerating rates of ice sheet melting in Antarctica and Greenland as the main driving factor behind the newly large (and concerning) estimate for sea level rise. This estimate represents what will happen if the earth’s temperature increase along the lines of the worst case scenario, nine degrees Fahrenheit by the end of the century. The estimate is also double the amount established as the tolerable upper limit in the United Nations climate science panel’s most recent major report.
The May 20th study follows a groundbreaking sea level rise study from 2013. That study predicted a sea level rise of between 1.7 and 3.2 feet by 2100. It established this range by considering only scenarios “likely” to occur, meaning that the scientists conducting the study looked at only 17 to 83 percent of the range of possibilities. Critics of that study worried that its range was too conservative and would downplay the possible extent of sea level rise, so the authors of the May 20th study looked at a range of 5 to 95 percent of possibilities. This expanded range led to the establishment of the 6.6 feet metric that has experts and ordinary people equally worried.
Should sea level rise occur at the levels the PNAS study suggests, the earth would lose a landmass equal in surface area to Libya. In addition to the swamping of vital, heavily populated coastal cities, many Pacific islands would simply cease to exist. Lands crucial to the global food supply, including the delta of the Nile, would be inundated with water and thus unable to contribute to international agriculture.
To understand the potential global upheaval that sea level rise might cause, the PNAS study’s lead author, Professor Jonathan Bamber of the University of Bristol, offered a helpful and alarming comparison to a modern humanitarian crisis. The Syrian refugee crisis, Bamber notes, displaced one million people to Europe. That number, Bamber notes, is a full 200 times smaller than the number of people that a 6.6 foot sea level rise would displace.