A new study warns that the ice sheets in Greenland and Antarctica are headed for irreversible melting, even if they manage to stabilize global temperatures by up to 2 degrees Celsius.
“If we miss this emissions target, according to our calculations, the ice sheets will break up and melt faster,” explains climate physicist Axel Timmermann of the Institute of Basic Sciences in Korea.
So far, the world’s sea level has risen by an average of about 20 cm over the past century. UN Secretary-General Antonio Guterres told Security Council debates in New York that the calculated acceleration would put one in ten people at immediate risk from sea-level rise.
He said: “For millions of people living in small island developing states and other low-lying coastal areas around the world, sea-level rise presents avalanche problems. We will see mass exodus there.
By adding feedback mechanisms missing from previous modeling, Busan National University climate scientist Jun-Young Park and his colleagues anticipate the critical tipping point coming faster than expected.
“Computer models that simulate the dynamics of ice sheets in Greenland and Antarctica often do not take into account the fact that a melting ice sheet can affect ocean processes, which in turn can feed the ice back,” explains Park.
As land and ocean ice melts at an ever-increasing rate, meltwater flowing into the oceans accumulates at the surface, reducing heat transfer from the depths and further warming the Earth’s interior. This extra heat erodes the frozen buttresses that prevent ice from sliding in Antarctica, allowing more meltwater to flow into the ocean.
The team notes that we are already seeing these effects in real time, with previously unheard-of events such as rain in Greenland and an increase in meltwater variability on the Antarctic ice shelf.
But Park and his team’s new calculations indicate that the process is irreversible and may begin at 1.8 degrees Celsius.
Only under mitigating circumstances, if temperatures were kept below 1.5°C, the model could have avoided a rapid acceleration of sea-level rise.
“If we don’t act, the retreat of the ice sheets will increase sea level by at least 100 cm over the next 130 years,” explains Timmermann. This is on top of other contributions such as thermal expansion of seawater.
Such a scenario would seriously affect megacities on every continent, including metropolitan centers such as Cairo, Mumbai, Shanghai, London, Los Angeles, New York and Buenos Aires.
While the potential is alarming, there are plenty of aspects affecting our complex ecosystems that new modeling doesn’t capture, such as the effects of narrow coastal currents.
Robin Smith, an atmospheric scientist who was not involved in the study, explains that “improving the latest climate models is critical.” Although more work is needed to mitigate the uncertainty in such projections, this study clearly demonstrates the importance of taking rapid action to reduce anthropogenic greenhouse gas emissions to reduce the risks associated with the loss of large ice sheets.
That doesn’t mean we have the luxury of waiting to find an answer. Every increase in warming we avoid gives us a better chance of helping future societies avoid the worst of a rapidly warming planet.
The study is published in the journal Nature Communications.
Source: Science Alert – Russia Today
