Arctic summer sea ice minimum was the sixth lowest on record. So we can all relax, right?
I’ll come back to that. However, Tamino at Open Mind points out that while the Arctic warms three to four times as fast as global warming, the Arctic winters are warming at a much faster rate.
Using the NASA data, which is about mid-range in the major players, Tamino finds that the overall average warming rate since 1985 in the Arctic, at 6.48°C/century is fully 3.4 times as fast as the global rate since 1985 of 1.90°C/century.
Looking at the seasonal data, the winter Arctic warming is 5.8 times as fast as the global rate, while the summer Arctic warming is only 1.4 times as fast.
Tamino suggests that the main reason is that with a fair bit of ice around the air temperature struggles to get much above 0°C in the summer.
That being said, this map showing sea ice extent at 13 October, 2018 compared to the 1981-2010 average is a worry, especially because the latter would be less than 1979:
The Scientific American has an article from April 2018 (pay-walled) which shows that winter Arctic ice extent in 2017 was almost 15% down on 1979 and a record. (Other reports place 2017 second, but not by much.)
That article also says that winter sea ice volume in 2017 had dropped an astounding 42.5% since 1979. Even more astounding was the summer ice volume, which had dropped 80%.
This article from NASA says the summer ice has retracted 40% in area during the summer minimum since the 1980s.
Furthermore the Carbon Brief article posts:
the maps below, which show the estimated thickness of Arctic sea ice in August 2018 (left) and how that compares to the 1981-2010 average (right). The dark blue shading in the right-hand map shows areas where ice is as much as two metres thinner than average for this time of year:
Then as Carbon Brief also said:
As Carbon Brief reported in its “State of the Climate” analysis in August, 2018 has seen record low amounts of “multiyear ice” – ice that has survived without melting for multiple years. In the first half of 2018, multiyear ice comprised just 34% of Arctic sea ice, with only 2% at least five years old. In the 1980s, upwards of 60% of Arctic sea ice was multiyear ice.
Back to the current sea ice extent, this screen shot from NSIDC site Arctic Sea Ice News & Analysis shows how it is tracking against the 1981-2010 mean and the 2012 record:
Could be heading into new territory.
By using the multi-year facility at the site we can see that after the earlier record of 2007, every single year has been on or below the interdecile range of the 1981-2010 median:
That’s 11 years straight. The Arctic ice appears to be in a new phase of fragility, and a further step change would not surprise. However, I think it would surprise the IPCC which said:
- B4.1.There is high confidence that the probability of a sea-ice-free Arctic Ocean during summer is substantially lower at global warming of 1.5°C when compared to 2°C. With 1.5°C of global warming, one sea ice-free Arctic summer is projected per century. This likelihood is increased to at least one per decade with 2°C global warming. Effects of a temperature overshoot are reversible for Arctic sea ice cover on decadal time scales (high confidence).
The following comes from Scott Waldman in New IPCC climate report actually understates threat, researchers say:
- The report also ignores “wild cards” in the climate system, or self-reinforcing feedbacks, said Veerabhadran Ramanathan, a professor of climate sciences at the University of California, San Diego. That includes thinning Arctic sea ice, which allows the ocean to absorb more heat, causing even more ice loss and diminished reflectivity in the region, he said. Such feedback loops have a real possibility of pushing the planet into a period of chaos that humans cannot control, he said.
This article Here’s what vanishing sea ice in the Arctic means for you summarises the implications of sea ice pretty well.
First of all is the albedo effect:
- The albedo effect is just a fancy expression for a very simple concept: white surfaces like ice and snow reflect about 80 percent of the Sun’s energy back into space. That allows us to keep cool. But if those white spots disappear, the darker ocean and land will absorb 90 percent of that heat, accelerating global warming.
Also you get a lot of water lying around on ice, like this, which reduces the reflectivity:
- The albedo effect due to vanishing sea ice is already responsible for about 25 percent of global warming, according to Jennifer Francis, a research professor at Rutgers University’s School of Environment and Biological Sciences.
Secondly, more open seas means bigger waves and more erosion, especially during storms.
Just this winter, as ice in the Bering Sea shrunk to record levels, huge waves pummeled the town of Diomede, engulfing homes. Erosion is also forcing the 400-plus residents of Newtok, Alaska, to relocate.
Here’s an image from another article – Mark Serreze’s Melting Arctic sends a message: Climate change is here in a big way at The Conversation:
Third, a warming Arctic has been shown to cause more extreme weather – recent research showed that when the Arctic is unusually warm, extreme winter weather is two to four times more likely in the eastern US.
Europe too. In my April 2014 post Extreme weather I showed this image of a weather map showing the Northern Hemisphere weather split by a stream of warm air directly across the North Pole:
Alaskan temperatures have been as much as 21°C above normal, while lower latitudes have frozen from cold air displaced. Europe and the NE of the North America seem to be developing a pattern of blazing hot summers, cold winters, storms and floods.
Then there is the weakening of the jet stream and the slowing of the major ocean circulation system known as the Atlantic Meridional Overturning Circulation ( AMOC), which I’ll look at again in a separate post.
Finally, there is the liberation of GHG’s especially methane through permafrost melting and ocean clathrates.
Serreze says there is a term Arctic amplification to cover the whole phenomenon.
Unfortunately the effects are not smooth and linear, subject to predictable measurement, which is the kind of science the IPCC likes to crystallize in its advice to policy makers. This leads to the burying from sight of significant global risk and a complacency that could mask nasty consequences.
Update: I forgot to mention Pollution is slowing the melting of Arctic sea ice, for now.
A study has found that human-produced aerosols are slowing the melting by a massive 23%.
- This puts us into a Faustian bargain. We want to reduce airborne pollution, like sulfur aerosols. But, if we do that, it makes the effects of greenhouse gas pollution worse.