The ice in the Arctic Ocean could completely melt, at least temporarily, in summers and this might happen before 2050 itself. The kind of climate-protection measures we take and the way we implement will determine how often and for how long this could happen. This result comes from a new research study involving 21 research institutes from around the world, coordinated by Dirk Notz from the University of Hamburg, Germany.
The team has analyzed 40 different climate models and results from them. The researchers considered the situation of Arctic sea-ice cover in a case with high future CO2 emissions and little climate protection. As expected, the ice disappeared quickly in summer in these simulations. However, the new study finds that Arctic summer sea ice also disappears occasionally if CO2 emissions are rapidly reduced.
“If we reduce global emissions rapidly and substantially, and thus keep global warming below 2 °C relative to preindustrial levels, Arctic sea ice will nevertheless likely disappear occasionally in summer even before 2050. This really surprised us,” said Dirk Notz, who leads the sea-ice research group at the University of Hamburg, Germany.
At present, the North Pole is covered by sea ice during the complete year. As summers pass by every year the area of the sea ice cover is decreasing. This drastically affects the Arctic ecosystem and climate: The sea-ice cover is a hunting ground and habitat for polar bears and seals, and keeps the Arctic cool by reflecting sunlight.
The way Arctic lose its sea-ice cover in the future depends on future CO2 emissions, the study shows. If emissions are reduced rapidly, ice-free years will occur occasionally. With higher emissions, the Arctic Ocean will become ice-free in most years. Hence, humans still have an impact on how often the Arctic loses its year-round sea-ice cover.
Technical details: The simulations used in this study are based on so-called SSP Scenarios (shared socio-economic pathways), which will also be used for the next IPCC report. Scenarios SSP1-1.9 and SSP1-2.6 are used to simulate a rapid reduction of future CO2 emissions, while scenario SSP5-8.5 is used to simulate largely unchanged future CO2 emissions. The study is based on simulations from the most recent generation of climate models, collected within the Coupled Model Intercomparison Project Phase 6 (CMIP6).
Research published in Geophysical Research Letters
