A new study warns that the ice sheets in Greenland and Antarctica are heading towards irreversible melting even if we manage to stabilize global temperatures by peaking at 2 degrees Celsius.
“If we miss this emissions target, the ice sheets will collapse and melt at an accelerated rate, according to our calculations,” explains climate physicist Axel Timmermann from the Institute of Basic Sciences in Korea.
To date, global sea levels have risen by an average of about 20 cm over the past century. UN Secretary-General António Guterres told Security Council discussions in New York that the estimated acceleration would put one in ten people at immediate risk due to sea level rise.
“For the hundreds of millions of people living in small island developing States and other low-lying coastal areas around the world, sea level rise is an avalanche of problems. We will see mass migration,” he said.
By incorporating feedback mechanisms that were missing in previous simulations, Busan National University climatologist Jun-Young Pak and colleagues expect the major tipping point to come sooner than expected.
“Computer models simulating the dynamics of the ice sheets in Greenland and Antarctica often do not take into account the fact that the melting of the ice sheet will affect ocean processes, which, in turn, can be reflected in the ice sheet,” explains Park.
As the ice on land and sea continues to melt at an ever-increasing rate, the meltwater flowing into the ocean concentrates on the surface, reducing heat transfer from the depths and further heating the Earth’s interior. This extra heat breaks down the frozen buttresses that prevent ice from drifting in Antarctica, causing more meltwater to enter the ocean.
The team notes that we are already seeing some of these effects in real time, such as events such as rain in Greenland and increased meltwater variability on the Antarctic Ice Shelf.
But new calculations by Park and his team show that this process is irreversible and could start as early as 1.8 degrees Celsius.
Only in mitigation scenarios keeping temperatures below 1.5°C could the model avoid such a rapid sea level rise.
“If we don’t take action, the retreating ice sheets will continue to raise sea levels by at least 100cm for the next 130 years. This will be in addition to other factors such as the thermal expansion of ocean waters.” Timmermann explains.
Such a scenario would severely affect metropolitan areas on every continent, including metropolitan areas such as Cairo, Mumbai, Shanghai, London, Los Angeles, New York and Buenos Aires.
While this possibility may be worrisome, there are many features affecting our complex ecosystems that have not been captured by the new modeling, such as the influence of narrow coastal currents.
Atmospheric scientist Robin Smith, who was not involved in the study, explains: “It is very important that improvements are made to the latest climate models. While more work is needed to mitigate the uncertainties in such forecasts, this study clearly demonstrates the importance of taking Rapid action to reduce anthropogenic emissions as soon as possible. greenhouse gases to reduce the risks associated with the loss of large ice sheets.”
This does not mean that we can afford the luxury of waiting for an answer. Every increase in warming we can avoid will give us a much better chance of helping future societies avoid the worst of a rapidly warming planet.
This study was published in the journal Nature Communications.
Source: Science Alert