As one of the most populous coastal cities on Earth, climate studies attempting to predict the future of New York City are plentiful – and few have anything optimistic to say. The latest, found in the Proceedings of the National Academy of Sciences, adopts a similarly dire theme as it reveals that the city will flood once every five years.
Extreme floods – those around 2.3 meters (7.5 feet) high – before industrialization took place just once every 500 years. Now, they’re occurring once every 25 years. By around 2030 at the earliest, they will be one-in-five year occurrences.
By 2300, if climate change mitigation isn’t dramatically stepped up, floodwaters will peak at around 15.2 meters (50 feet). This will kill scores of people and create millions of refugees.
As you may expect, anthropogenic climate change is to blame. According to the study’s team of international authors, storm surges – the swells of water that accompany hurricanes – will be greatly exacerbated by the phenomenon at an unprecedented pace.
Storm surges occur when extremely low-pressure zones (i.e. hurricanes) drift over coastal waters. The sea is essentially drawn skywards, and other than building fairly high walls along the coast, little can be done to defend a city against them.
Previous research has clearly indicated that climate change is making hurricanes more powerful by providing them with warmer waters, more moisture-laden air, and higher sea levels. Rising sea levels also mean that storm surges will be far worse in the future.
Apart from causing catastrophic flooding – especially if combined with extreme rainfall – surges are too fast to outrun, and many people perish as they slam into the lowest-lying areas of cities.
In the case of NYC, the team explains that, using cutting-edge climate models that take into account a vast range of physical parameters, “rare” storm surges are already far more common than they used to be. In the next three decades, the shocking events of Superstorm Sandy will be a regular event.
The research, led by Rutgers University, The Pennsylvania State University, and others, points out that 400,000 people already live on a floodplain afflicted by one-in-100 year events. This suggests that by 2030, these people will be in a near-permanent state of flood risk.
Unlike most studies of this ilk, it also contains some unexpected good news. Although the flood risk has gone up from storm surges, modeling reveals that the hurricanes responsible for their deliverance will probably track more eastwards in the future, meaning they could miss the city altogether.
There is a fair bit of uncertainty here, but this study suggests that the future is decidedly dangerous, and we should do all we can to try and avoid it becoming a reality.