An expensive time bomb is ticking in the San Francisco Bay Area following the publication of a new study that has found large parts of the region to be sinking at an alarming rate. The threat also covers the reclaimed land that is home to San Francisco International (SFO) and much of its infrastructure.

Scientists at NASA’s Sea Level Change planning team and at Arizona State University’s School of Earth and Space Exploration (SESE) published the findings on March 7 in the Science Advances journal.

Much of the Bay Area was previously known to be sinking at a rate of no more than 2 millimetres per year, especially on unmodified land. However, on areas where land reclamation has taken place, the rate of sinking has been found to be around 10 millimetres per year — nearly half an inch.

Because of this, some of the region’s most densely populated areas are now facing a pressing risk of damage and regular flooding — not in many generations' time, but much sooner. This threatens an enormous economic impact on some areas, with damage to ground surfaces and subterranean services.

In the case of SFO, which handles over 200,000 landings and 56 million passengers per year, the threat is huge. It is estimated that the runways and taxiways could be underwater completely by 2100.

As well as SFO, other areas of the Bay, such as Treasure Island and Foster City, are also at significant threat from the much greater rate of sinking.

When discussing what can be done about the problem, the document’s lead author Manoochehr Shirzaei said the process of ground sinking and sea level rising magnifies the problem. "The ground goes down, sea level comes up, and flood waters go much farther inland than either change would produce by itself."

The world’s most famous "underwater" airport is Amsterdam Schiphol in the Netherlands, which sits three meters below sea level. Its inland location and complex system of dams and levees means there is no threat to the airport. However, in San Francisco’s case the shore surrounds the airport’s four runways, which jut out into the Bay.

Funding for the creation and preservation of wetlands is already in place, and the construction of concrete sea walls and defences is likely to be the next stage in protecting important, immovable assets such as airports and areas of population and commerce. The Bay Conservation and Development Commission will work on firm recommendations and proposals over the coming year.

What San Francisco Airport will look like by the time the runways are set to be underwater is difficult to know, and the airport itself has not yet made comment on the recent report. Perhaps in 82 years’ time aircraft will no longer require runways. But what is certain is that the demand for travel to and from the city will only get stronger and plans need to be made sooner rather than later over how to tackle this environmental catastrophe long before it is upon us.