This new study(made by Georgia Rose Grant, GNS Science and Timothy Naish, Victoria University of Wellington) shows that a 2°C warming would set off wide spread melting in Antartica.
Scientists drilled at a site in New Zealand, named the Whanganui Basin, that contains marine sediments of high resolution. By doing this they managed to measure past changes in sea levels, then they made a record of global sea-level changes. This record is much more precise than what was previously possible.
The earth has experienced warmer periods in the past, the period which is similar to today’s situation Is the Pilocene geological epoch (3 million years ago). This period is the last that showed a 400 parts per million concentration of Co2 in the atmosphere and a global temperature 2°C warmer than pre-industrial time.
The analysis made by Grant and Naish shows that in this period at least one third of Antarctica’s ice melted. This caused an astonishing rise of 20 meters in the coming centuries.
Compared to today’s situation this means that if our emissions of Co2 do not drop in the next years by 2030 we could be in a Pilocene scenario, exceeding the 2°C Paris target. If we continue to follow our current emissions trajectory, the median (66% probability) global sea level reached by the end of the century will be 1.2 metres higher than now, with two metres a plausible upper limit (5% probability). This trend will obviously continue throughout the 2100.
This study has important implications for the stability and sensitivity of the Antarctic ice sheet and its potential to contribute to future sea levels. The concept is that a tipping point in the Antarctic ice sheet may be crossed if global temperatures are allowed to rise by more than 2℃. This could end up in even a third of the Antarctica ice sheet being committed to melt-down that could result in a 20 meters rise In the sea level in the next centuries.