Sea level could rise faster than expected | Life

WASHINGTON, May 22 – The global sea level could rise by two meters and displace tens of millions of people by the end of the century, according to new projections that double the UN's baseline estimates.

The vast expanses of ice in Greenland and Antarctica contain enough icy water to lift the world's oceans for tens of meters. The expansion of water when the oceans warm up also contributes to the rise in sea level.

But it is notoriously difficult to predict how fast they will melt as the planet heats up.

The United Nations Intergovernmental Panel on Climate Change (IPCC) announced in its Fifth Assessment Report 2013 that in current emission trajectories – a "status quo" scenario known as RCP8 .5, it would be likely that the latter would increase by one meter by 2100.

This forecast has since been viewed as cautious, as global warming levels of greenhouse gas emissions continue to increase year by year, and satellites are showing accelerated melting rates. massive ice patches over Antarctica and Greenland.

This week, a group of leading scientists from around the world published expert advice on the situation, drawing on their own experience and observations.

Although there was still a large margin of error, they found it "plausible" that, in the typical emission scenario, sea-level rise could exceed two meters by 2100.

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

"A rise in sea level of this magnitude would clearly have profound consequences for humanity," they said.

"The real risks"

The Paris agreement on climate, concluded between nations in 2015, aims to limit the rise in global temperature well below two degrees Celsius and encourages countries to work towards a ceiling of 1 , 5 ° C.

In October, the IPCC released a major climate report calling for a drastic and immediate reduction in the consumption of coal, oil and gas to curb the rapid rise in greenhouse gas levels in the world. # 39; s atmosphere.

This report, however, did not include revised estimates of sea level rise.

Earth has already warmed 1C since the pre-industrial era, contributing about 3mm of sea level each year.

The authors of the new study, published Monday in the journal Proceedings of the National Academy of Sciences, argue that the prediction of IPCC sea-level rise was too limited in focusing on what was "likely" to occur.

With larger probabilities – 5 to 95% probability – they found that sea warming below 2 ° C could reach 36-126 cm by 2100.

In a warming world of 5 ° C – unlikely but certainly not impossible given the demand for fossil fuels expected in the coming decades – they calculated a 5% risk of sea-level rise greater than two meters at 238 cm.

Willy Aspinall, from the School of Earth Sciences at Bristol University, said he hoped the study would provide decision-makers with a more specific worst case scenario "crucial for robust decision-making".

"Limiting attention to the" likely "range, as was the case in the IPCC's Fifth Assessment Report, may be misleading and likely lead to a misjudgment of actual risks." he added. – AFP