Current rate of warming will cause catastrophic melting of Antarctic ice

Missing the temperature targets set forward by the Paris Agreement will lead to an irreversible tipping point in Antarctica, according to the authors of a new study. At the current rate of global warming, Antarctic ice loss will trigger unstoppable sea level rise.

Study lead author Rob DeConto is the co-director of the School of Earth & Sustainability at the University of Massachusetts Amherst. He said that if the world continues to warm, the huge glaciers in Antarctica could begin behaving like their smaller counterparts in Greenland, which would be disastrous in terms of sea level rise.

The researchers used a computer model to project the response of the Antarctic Ice Sheet to several different warming scenarios, including the Paris Agreement target of two degrees Celsius of warming and an aspirational 1.5 degree scenario. The team also modeled the impacts of three degrees of warming, which the world is currently on track to exceed.

The model showed that the impact of three or more degrees of warming would drastically accelerate the pace of sea-level rise by 2100. 

The experts warn that if global warming continues on its current trajectory, a tipping point will be reached by 2060, past which the consequences would be “irreversible on multi-century timescales.”

If the 1.5 and two degree Paris Agreement temperature targets are achieved, the Antarctic Ice Sheet will contribute between 6 and 11 centimeters of sea level rise by 2100. However, the model showed that the current rate of global warming will cause a major jump in melting.

Unless ambitious action is taken to mitigate rising temperatures by 2060, no type of human intervention will be able to prevent Antarctic ice from contributing 17 to 21 centimeters of sea-level rise by the end of this century. 

On longer timescales, the contribution of the Antarctic Ice Sheet will reach a globally catastrophic level of 10 meters or more by 2300 if global warming continues at the current rate.

According to DeConto and colleagues, the very architecture of the Antarctic Ice Sheet itself plays a key role in ice loss. The sheet naturally flows downhill into the ocean, where it begins to melt. This melting is limited by a ring of ice shelves, which act as dams that keep the ice sheet from sliding rapidly into the ocean. 

But if global warming is not slowed, the risk of the protective ice shelves melting will increase significantly, and their collapse would trigger rapid Antarctic melting.

“These results demonstrate the possibility that unstoppable, catastrophic sea level rise from Antarctica will be triggered if Paris Agreement temperature targets are exceeded,” wrote the study authors. 

“It’s critical to be proactive in mitigating climate change now through active international participation in reducing greenhouse gas emissions and by continuing to ratchet down proposed policies to meet the ambitious Paris Agreement targets,” said study co-author Daniel M. Gilford. 

The study is published in the journal Nature.

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By Chrissy Sexton, Earth.com Staff Writer