Under this scenario, Antarctica and the Southern Ocean undergo widespread and rapid change, with global consequences. Warming of the ocean and atmosphere result in dramatic loss of major ice shelves. This causes increased loss of ice from the Antarctic ice sheet and acceleration of sea-level rise to rates not seen since the end of the last glacial period more than 10,000 years ago.
Warming, sea-ice retreat and ocean acidification significantly change marine ecosystems. And unrestricted growth in human use of Antarctica degrades the environment and results in the establishment of invasive species.
In the second scenario, ambitious action is taken to limit greenhouse gas emissions and to establish policies that reduce human pressure on Antarctica’s environment.
Under this scenario, Antarctica in 2070 looks much like it does today. The ice shelves remain largely intact, reducing loss of ice from the Antarctic ice sheet and therefore limiting sea-level rise.
An increasingly collaborative and effective governance regime helps to alleviate human pressures on Antarctica and the Southern Ocean. Marine ecosystems remain largely intact as warming and acidification are held in check. On land, biological invasions remain rare. Antarctica’s unique invertebrates and microbes continue to flourish.
The choice is ours
We can choose which of these trajectories we follow over the coming half-century. But the window of opportunity is closing fast.