Cut emissions to avert catastrophic sea-level rise

Scientists behind a landmark study of the links between oceans, glaciers, ice caps and the climate delivered a stark warning to the world: slash emissions or watch cities vanish under rising seas, rivers run dry and marine life collapse. Days after millions of young people demanded an end to the fossil-fuel era in protests around the globe, a new report by a U.N.-backed panel of experts found that radical action may yet avert some of the worst possible outcomes of global warming. But the study was clear that allowing carbon emissions to continue rising would upset the balance of the geophysical systems governing oceans and the frozen regions of the Earth so profoundly that nobody would escape untouched.

We are in a race between two factors, one is the capacity of humans and ecosystems to adapt, the other is the speed of impact of climate change. This report…indicates we may be losing in this race. We need to take immediate and drastic action to cut emissions right now,” IPCC Chair Hoesung Lee said at the presentation of the report in Monaco.

Finalised in a marathon 27-hour session of talks in Monaco between authors and representatives of governments, the report was the culmination of two years’ efforts by the U.N.-backed Intergovernmental Panel on Climate Change (IPCC). Compiled by more than 100 authors who crunched 7,000 academic papers, the study documents the implications of warm, fast-melting ice sheets in Greenland and Antarctica and shrinking glaciers for more than 1.3 billion people living in low-lying or high-mountain regions.

The report projects that sea levels could rise by one meter (3.3 feet) by 2100 — ten times the rate in the 20th century — if emissions keep climbing. The rise could exceed five meters by 2300. In the Himalayas, glaciers feeding ten rivers, including the Ganges and Yangtze, could shrink dramatically if emissions do not fall, hitting water supplies across a swathe of Asia. Thawing permafrost in places like Alaska and Siberia could release vast quantities of greenhouse gases, potentially unleashing feedback loops driving faster warming.