Rising sea levels threaten a 'mass exodus', UN alert

The UN Secretary-General, António Guterres, addressed the UN Security Council this week noting that the continued rise in sea level will generate "a mass exodus of entire populations on a biblical scale", for which he insisted that it is necessary to reduce carbon emissions and address factors such as poverty, which have an impact on the rise in sea level.

The Secretary-General was also emphatic that rising sea levels threaten lives and economies, something that will have "dramatic implications" for world peace.

“Low communities and entire countries could disappear forever. We would witness a mass exodus of entire populations on a biblical scale. And we would see increasingly fierce competition for freshwater, land and other resources,” he added.

"Global mean sea level has risen faster since 1900 than in any previous century in the last 3,000 years," he said. "The global ocean has warmed faster over the last century than at any time in the last 11,000 years."

Mass exodus of entire populations

According to data cited by Guterres, the global mean sea level will rise by 2 to 3 meters (about 6.5 to 9.8 feet) over the next 2,000 years if warming is limited to 1.5 degrees Celsius. With a 2-degree Celsius rise, seas could rise as high as 6 meters (19.7 feet), and with a 5-degree Celsius rise, seas could rise as high as 22 meters (72 feet), according to the WMO.

“Our world is hurtling past the 1.5-degree warming limit that a habitable future requires, and with current policies, it is approaching 2.8 degrees, a death sentence for vulnerable countries,” he said.

The consequences are unthinkable, Guterres said. Low-lying communities and entire countries could disappear, the world would witness “a mass exodus of entire populations on a biblical scale,” and competition for freshwater, land and other resources would become increasingly fierce.

Ocean warmed faster in last century

According to the World Meteorological Organization (WMO), the ocean has warmed faster in the last century than in the last eleven thousand years, causing the water to expand and the polar glaciers to melt.

Guterres amuses that although the rise in sea level is inevitable taking into account the increase in global temperature, the consequences of not addressing this problem will be "unthinkable". Guterres also made a special call on people who must move for climate reasons. “People's human rights do not disappear because their homes disappear. Yes, this means international refugee law.''

The Human Rights Committee ruled in 2020 that it is "illegal" for governments to return people to countries where they could be threatened by the climate crisis.

Sea level rise is imminent if warming exceeds 1.8ºC

Although most of the world's coastal populations are already preparing for sea level rise, agreeing on measures to avoid catastrophes is extremely difficult because there is no consensus on how quickly the ice sheets will melt.

Now, a new study published Tuesday in Nature Communications warns that the "irreversible loss" of ice in Antarctica and Greenland - and the corresponding rise in sea levels - may be "imminent" if global warming does not stabilize below of 1.8ºC in relation to pre-industrial levels.

The melting of ice sheets is potentially the factor that contributes the most to sea level change, and historically the most difficult to predict because the physics that governs its behaviour is very complex.

In fact, the latest climate model projections presented in the 6th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) do not agree on how quickly the major ice sheets will respond to global warming.

In parallel, “computer models simulating the dynamics of the Greenland and Antarctic ice sheets often do not take into account the fact that melting of the ice sheet will affect oceanic processes, which, in turn, they can feed back into the ice sheet and the atmosphere,” adds Jun Young Park, from the IBS Center for Climate Physics at Pusan ​​National University (South Korea).

Zero carbon emissions by 2060

Now, using a new computer model, which captures for the first time the coupling between ice sheets, icebergs, the ocean and the atmosphere, the team found that the spillover effect of the ice sheets and sea level can only be avoided if the world reaches net zero carbon emissions by 2060.

"If we don't reach this goal, the ice sheets will disintegrate and melt at an accelerated rate, according to our calculations," he warns.

“If we take no action, the retreating ice sheets would continue to raise sea levels by at least 100 centimetres in the next 130 years. And this would be added to other contributions, such as the thermal expansion of ocean water”, points out Axel Timmermann, director of the IBS Center for Climate Physics.

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