Climate: Bad News from the Ice World
The melting of glaciers contributes to the rise in ocean levels, which puts the population of several countries at risk, such as Bangladesh, Pakistan, Egypt, Thailand, Nigeria or the Vietnam. (File photo)
Ice caps, whose melting would raise the oceans by several meters, could well collapse with half a degree of additional warming of the climate, according to recent studies which shed light on their hitherto unsuspected fragility.
The Greenland and Antarctic ice caps have lost more than 500 billion tonnes per year since 2000, the equivalent of six swimming pools Olympics every second.
But climate models had so far underestimated their contribution to future sea level rise, accounting only for the effect of rising air temperatures on sea ice. – and neglecting the complex interactions between the atmosphere, oceans, ice caps and some glaciers.
Researchers from South Korea and the United States have established what would be sea level rise by 2050 according to different scenarios submitted by UN climate experts, the IPCC.
If current climate policies continue – including countries' commitments under the 2015 Paris Climate Agreement – melting in Antarctica and Greenland would result in increased x27; about half a meter from the water level.
A figure that would rise to 1.4 meters in the worst scenario, in the event of a significant increase in greenhouse gas emissions greenhouse.
The study by these scientists, published this week in the journal Nature Communication, also specifies when runaway melting and the uncontrollable disintegration of these ice sheets could occur.
Our model has thresholds between 1.5°C and 2°C of warming – 1.8°C being our best guess – for accelerating ice loss and rising sea levels , explained Fabian Schloesser, of the University of Hawaii, co-author of the study. Temperatures have already risen nearly 1.2°C around the world since pre-industrial times.
Scientists have long known that the ice sheets of the West Antarctica and Greenland – which could raise ocean levels by 13 meters in the long term – had tipping points beyond which their disintegration would be inevitable. But the temperatures associated with this phenomenon had never been precisely established.
According to scientists, the Thwaites glacier is melting faster than expected. (File photo)
Other studies published this week in Naturealso show that the Thwaites Glacier in western from Antarctica, fractures in an unsuspected way.
This Great Britain-sized glacier has already retreated 14 kilometers since the 1990s, but the phenomenon was not well understood due to lack of data.
An expedition of British and American scientists drilled a hole the equivalent of two Eiffel Towers (600 meters) deep through the thick tongue of ice pushed by Thwaites into the sea of ;Admundsen.
There they found signs of accelerated erosion – with inverted stair-like formations – as well as cracks opened up by seawater.
Warm water seeps into cracks and wears down the glacier at its weakest point, said Britney Schmidt, author of one of the studies and a professor at the #x27;Cornell University in New York.
Another study, published in Earth's Future, mentions for his part that the rise of the oceans will destroy arable land as well as sources of drinking water and will force millions of people into exile sooner than expected.
“The time we have to prepare for greater flood exposure may be much less than previously assumed.
— Authors of a study published in Earth's Future
The estimates we had were heavily based on data misinterpreted: when measuring the altitude of coastal regions using radar, the tops of trees or roofs have often been confused with ground level. It is therefore in reality much lower than previously thought.
Tens of millions of people are particularly vulnerable in the coastal areas of countries such as Bangladesh , Pakistan, Egypt, Thailand, Nigeria or Vietnam.