The worst-case climate scenario for coastal cities is known as a “pulse.”
In that situation, abnormally warm water could cause the glaciers that hold back ice sheets on top of Antarctica and Greenland to collapse. That would cause massive quantities of ice to pour into the world’s oceans, which could lead to extremely rapid sea-level rise around the world.
If such a scenario were to occur, current sea-level rise predictions for vulnerable cities like Miami would be far too low.
Right now, scientists predict Miami will likely be surrounded by seas up to 7 or 8 feet higher than they were in 1900 by the end of this century. But in the case of a pulse, some experts think South Florida could see 10 to 30 feet of sea-level rise by 2100.
Commentary by The Secular Jurist: Compare this real story to a fictional one I wrote as a novel in 1997, completed in 2011, and published in 2012 as The Martian Patriarch. Here’s the relevant excerpt:
Overpopulation began adversely affecting the global environment in the Industrial Age, escalated during the Information Age, and reached a critical tipping point in what later became known as the Dystopian Age. Eventually, technological innovations had begun to reduce the per capita emissions of greenhouse gases and other harmful pollutants, but this was offset by the continued growth in the world’s population. Average surface temperatures rose steadily until the last of the Greenland glaciers quickly melted away, and the West Antarctic ice shelves collapsed in rapid succession. The latter event destabilized the massive West Antarctic continental ice sheet, allowing it to break up and flow into the oceans. All this happened concurrently, which triggered a sudden surge in sea levels that transpired over a brief period of a few months – astonishing even those who had issued the most dire climate warnings. Coastal and lowland communities were insufficiently prepared to evacuate the millions of inhabitants, and were inundated long before their hastily conceived plans could be implemented. What made matters worse, was the unexpected increase in the frequency and intensity of violent storms. As a result, the actual flooding was fiercely episodic rather than gradual. The environmental domino effects were ghastly. Global weather patterns changed abruptly, turning most of the surviving agricultural areas into useless wastelands. Regional wars broke out from numerous disputes over dwindling resources that collectively grew into worldwide revolution in 2061.
Getting around San Francisco, especially at night, was not quite as easy as when Bolton was a child. The city had become nothing more than a cluster of natural, and manmade, islands connected by a maze of viaducts and elevated expressways. The financial district, once dominated by the wide corridor of Market Street running through it, was now under twenty feet of salt water. Several of the original skyscrapers were saved by retrofitting their structures to a marine environment, which allowed continued use of the floors above the water line; but, their occupants were gradually relocating further inland. It was only a matter of time before the once majestic city was abandoned to the fish.