Global warming has increased the loss of ice sheets all over the world and in turn, the reduction in ice contributes to global warming in several ways, creating a vicious cycle that does not spell good news for Earth. A new study in Nature Communications assessed how much the loss of ice contributes to an increase in temperature.
The study estimates that if the Arctic ocean was to lose its ice coverage completely, it would add 0.2°C (0.36°F) to the average increase of global temperatures. The same increase would happen again if Greenland and West Antarctica lost their glaciers, resulting in a median additional global warming of 0.4°C (0.72°F). As we struggle to keep the global average temperature increase below 2 °C (3.6 °F), the difference that ice loss makes is significant.
"If global ice masses shrink, this changes how much of the sunlight that hits Earth's surface is reflected back into space. Decreasing ice cover in the Arctic exposes more of the darker ocean water that absorbs more energy," lead author Nico Wunderling, from the Potsdam Institute For Climate Impact Research, said in a statement. "This is referred to as albedo feedback. It's like wearing white or black clothes in summer. If you wear dark, you heat up more easily."
The albedo feedback accounts for 55 percent of that possible increase. But ice melting also changes the concentration of water vapor in the atmosphere. A more humid world is a world that retains heat better – really not what we currently want. It also changes cloud coverage, again leading to a temperature increase. Water vapor changes account for 30 percent of that 0.4°C (0.72°F), the remaining 15 percent is from changes in cloud coverage.
"[E]very tenth of a degree of warming counts for our climate," said Ricarda Winkelmann, who led the research group. "Preventing Earth system feedback loops, or vicious circles, is thus more urgent than ever."
The team only estimated how the loss of ice will affect temperatures but there are other effects to consider. The polar regions have been able to trap greenhouse gases for millennia and these are slowly being released. Researchers from the International Siberian Shelf Study Expedition 2020 have reported the first detection of methane being released from the continental slope in the Laptev Sea. The detection comes from a depth of 300 meters (984 feet) off the East Siberia coast.
The team wrote on Facebook that they believe that the emissions are still modest at this time, but it's a new and worrying alarm bell for the effects of the climate crisis in the Arctic. The polar regions might feel distant but safeguarding them has a global impact.