Global sea levels may rise by over three metres

London

Global sea levels could rise by over three metres — half a metre more than previously thought — this century alone, according to a new study.

An international team, including researchers from University of Southampton in the UK, looked at what might happen if carbon dioxide emissions continue unabated.

Using new projections of Antarctic mass loss and a revised statistical method, they concluded that a worst-case scenario of a 2.5 to three-metre sea level rise was possible by 2100.

"It might be an unlikely scenario, but we cannot exclude the possibility of global sea levels rising by more than three metres by the year 2100," said Professor Sybren Drijfhout from Southampton.

"Unabated global warming will lead to sea-level rise of many metres — possibly more than ten metres — within a few centuries, seriously threatening many cities all over the world that are built in low-lying river deltas," said Drijfhout.

The research is consistent with the National Oceanic and Atmospheric Administration's (NOAA) recent adjustment of its possible future high-end sea-level rise from two to 2.5 metres.

However, the new study published in the journal Environmental Research Letters, integrated different model estimates with a new statistical method, whereas the NOAA estimate relied on expert judgement.

Recent observation and modelling studies have shown the future melt of Antarctica might happen dramatically faster than previously thought.

Drijfhout and scientists at the Royal Netherlands Meteorological Institute, which led the research, took this and other factors - including ocean warming, glacier melt, land water storage and Greenland ice sheet melt - into account to create their projection.

"This is the first time that robust statistical techniques have been used to develop a scenario like this, whereas previous high-end sea level projections have always been based on subjective expert judgement," said Drijfhout.

"It is important for policy-makers and the general public to know what the consequences might be when carbon dioxide emissions are not decreased, especially as there is a severe time-lag between emission-reduction and the sea-level rise response.

"Also, the construction of artificial flood defences need to take account of low-probability events, including the possibility that the international community fails to take adequate measures in reducing measures," Drijfhout added. — PTI