Global sea level can rise to 3 meters if the Thwaites glacier collapses in West Antarctica.
Sea level rises threaten cities from Shanghai to London, to low-lying parts of Florida or Bangladesh, and to entire nations such as the Maldives.
In the UK, an increase of 2 meters or more can, for example, lead to areas such as Hull, Peterborough, Portsmouth and parts of East London and the Thames Estuary with the risk of being submerged.
The collapse of the glacier, which could begin for decades, can also submerge large cities such as New York and Sydney.
Parts of New Orleans, Houston and Miami in the southern US would also be hit particularly hard.
A 2014 study, viewed by the union of involved scientists, looked at 52 sea level indicators in US communities.
It appeared that tidal nuisance will increase dramatically in many locations on the east and gulf coast, based on a conservative estimate of predicted sea level rises based on current data.
The results showed that most of these communities will experience a sharp increase in the number and severity of tidal nuisance in the coming decades.
By 2030, more than half of the 52 communities studied will experience an average of 24 floods per year in exposed areas, assuming moderate projections of sea level rise. Twenty of these communities could see a tripling or more in tidal events.
The Mid-Atlantic coast is expected to see some of the largest increases in flooding frequency. Places such as Annapolis, Maryland and Washington, DC can expect more than 150 tidal floods per year, and different locations in New Jersey can see 80 tidal floods or more.
In the UK, an increase of two meters (6.5 ft) by 2040 would almost completely cover large parts of Kent, according to the results of a paper published in Proceedings of the National Academy of Science in November 2016.
Areas on the south coast such as Portsmouth, as well as Cambridge and Peterborough would also be hit hard.
Cities and villages around the mouth of the Humber, such as Hull, Scunthorpe and Grimsby, would also experience intense flooding.