We need only look to the world’s ice cover to see the urgency with which emissions need to come down, scientists told delegates at this week’s climate talks in Bonn, Germany.
At a press conference today, US and German scientists updated negotiators and journalists with the latest science on the state of Arctic sea ice, the Antarctic continent and thawing permafrost.
New observations gathered since the Intergovernmental Panel on Climate Change (IPCC) report show the cryosphere in serious and irreversible decline, they warned.
Sea ice in decline
Arctic sea ice has been retreating rapidly in recent years as a result of greenhouse gases building up in the atmosphere, explained Dr Dirk Notz, sea ice expert at the Max Planck Institute in Germany. The biggest losses are happening in summer, he said:
In March, Arctic sea ice reached its lowest maximum extent in the satellite record. Last week, the US National Snow and Ice Data Centre confirmed Arctic sea ice extent for May was the third lowest on record.
Scientists’ current understanding is that temperature changes as a result of greenhouse gases are causing winds to blow stronger offshore in the Southern Ocean that surrounds Antarctica, driving the sea ice outwards. Notz said:
Model simulations suggest sea ice could be gone from the Arctic in summer by mid-century. But if we stop emitting greenhouse gases, the chances of losing sea ice diminish quickly, he said:
Ice sheets at risk
Turning from sea ice to land ice, a few regions of West Antarctica have grabbed scientists’ attention in the past year, explained Prof Ricarda Winkelmann from the Potsdam Institute for Climate Impact Research. Each has the potential to destabilise, raising global sea levels.
The Amundsen Basin in West Antarctica, which houses the Pine Island and Thwaites glaciers, is one of these “hotspots.” Winkelmann explains:
Once the glaciers in this region drain into the ocean, the volume of water will raise global sea levels by one metre. The question is how fast that will happen, said Winkelmann.
A second region that’s been discussed a lot this year is the Antarctic Peninsula. Warm water is reaching the ice shelves and thinning them from the bottom up, recent research shows.
The scientists are watching the Totten glacier in East Antarctica closely, as the same process of irreversible collapse could be at work there too, they say.
Totten is currently thinning faster than any other glacier in East Antarctica and, if it melts, could raise sea levels by 3.5m – more than the whole of the West Antarctic ice sheet put together.
Carbon has been accumulating in permafrost for many thousands of years, but it is starting to be released as warmer temperatures are causing the once-permanently frozen ground to thaw.
Scientists currently estimate there is 1,500bn tonnes of carbon currently locked away in permafrost. That’s twice as much as in the atmosphere, explained Dr. Susan Natali, an expert in permafrost feedbacks on climate from the Woods Hole Research Center in the US.
If even a small amount of that carbon escapes to the atmosphere, it could lead to a significant increase in global greenhouse gas emissions, said Natali.
If emissions stay very high, scientists expect to see a 70% loss in permafrost worldwide by 2100. This could be reduced to 30% if global temperatures are limited to 2C above pre-industrial levels, Natali explained.
How much carbon will find its way to the atmosphere is a complex question. But current estimates are for 130-160bn tonnes of carbon to be released by 2100. That’s on par with current rate of emissions from the whole of the United States, the world’s second largest emitter.
The actions that we take now in terms of our fossil fuel emissions will have a significant impact on how much permafrost is lost and, in turn, how much carbon is released, said Natali:
A matter of urgency
This new science isn’t feeding into international climate policy as it should be, said Pearson:
Notz urged policymakers to view climate change as a current, not a future, challenge. He said:
In light of the wealth of new science, Pearson said she would like to see ambitions raised ahead of a global climate agreement in Paris later this year. She said:
As well as greater ambition, Pearson said she wants to see the flexibility in the final Paris text to enable countries to raise their targets without going through a lengthy negotiation process.
Changes are taking place faster in the cryosphere than anywhere else, making it an ideal lens through which to view climate change negotiations, Pearson concluded. The processes taking place cannot be reversed and while they won’t happen while these policymakers are in office, limiting the damage for future generations is a critical part of leadership, she said.
Main image: Icebergs in Disko Bay, Greenland.
UPDATE: The article was updated on June 10th once Dr Dirk Notz's slides became available online. The figure from his presentation compares changes in Arctic and Antarctic sea ice.
Irreversible loss of world's ice cover should spur leaders into action, say scientists