WASHINGTON: Global Sea Levels could Rise by two metres or 6.5 feet and displace tens of millions of people by the end of the century, according to new projections that double the UN’s benchmark estimates.

The United Nations’ Intergovernmental Panel on Climate Change (IPCC) said its 2013 Fifth Assessment Report that under current emissions trajectories — a “business-as-usual” scenario known as RCP8.5 — would likely rise by up to one metre by 2100.

The authors said the area of land lost to the ocean could be equivalent to that of France, Germany, Spain and Britain combined and would displace more than 180 million people.

The Paris climate deal, struck between nations in 2015, aims to limit global temperature rises to well below two degrees Celsius (3.6 Fahrenheit), and encourages countries to work towards a 1.5C cap.

In October the IPCC released a landmark climate report that called for a drastic and immediate drawdown in coal, oil and gas consumption in order to arrest the rapid rise in the levels of greenhouse gases in the atmosphere.

The authors of the new study, released on Monday in the journal Proceedings of the National Academy of Sciences, argue that the IPCC’s sea-level rise prediction was too constrained by focusing on what was “likely” to happen.