About 10 days ago Germany’s Alfred Wegener Institute (AWI) put out a press release on global sea ice. In it AWI scientist Marcel Nicolaus and Lars Kaleschke of the Hamburg Cluster of Excellence for Climate Research (CliSAP) confirmed the “long-term downward trend in the Arctic.”
Somewhat annoyed by that conclusion, I sent the 2 scientists an e-mail asking them if they would bet $1000 on the mean 2017-2022 September sea ice will be less than the mean 2007-2012 September sea ice – just to see if they were ready to put their money where their mouth is. I even made my bet public here.
Unfortunately both Marcel Nicolaus and Lars Kaleschke have yet to reply. No surprise.
I also sent similar e-mails to other scientists at leading institutes all over the world, mainly those that actively claim that the Arctic is melting, asking if betting on less sea ice over the next 10 to 20 years was a safe bet. Some replies have come in. The results of which I will disclose soon in the future.
One excellent response I got was from Dr. Dirk Notz of the Max-Planck Institute for Meteorology (MPI-M) in Hamburg. I’m very thankful he took the time to send it. In fact he has been so kind to give me permission for me to post it. His reply (my emphasis):
thanks for being in touch, and sorry for the slow reply. I was at a meeting with surprisingly little internet access.
Regarding the bet: I’d be very careful to place a bet in either direction, simply based on our understanding of the system from climate-model simulations. These basically say that on short time scales, such as from one decade to the next, internal variability can cause both an increase or a decrease of the ice coverage. To exemplify this, I’ve attached a slide that shows 30-year long trends from our climate-model simulations (Trends_for_talk3.pdf).
There you see 30-year long trends for different start dates in our simulations, which vary wildly. This would even more be the case for 10-year long trends. Hence, I wouldn’t put money on a further decrease of the ice cover in the years to come, nor on the opposite.
I’ve also attached a plot showing two of the simulations with our Earth-System Model, which suggest that there might be slightly less sea ice in the next decade, but other simulations show a slight increase on these short time scales.
Hence, on time scales such as one decade, the ice cover could well increase a bit (as you are suggesting), but it might also decrease. This depends in my opinion primarily on weather patterns in individual summers – nothing we can predict at the moment.
Having said this, however, one of the presentations at the meeting I’ve just been to by Andrey Proshutinsky went in the same direction as you’re suggesting, namely that because of ocean cycles there will be a recovery of sea ice in the years to come. However, I don’t believe this to be a very robust finding that I would put money on at the moment. It’s nevertheless certainly something that we’ll investigate more in the time to come.
I hope this helps you (and I also hope that it’ll save you from eventually having to pay $1000!).
Please let me know if any further questions should come up.
Dr. Notz is Head of the Research Group Sea ice in the Earth system, where they “use large-scale coupled climate models to better understand the evolution of sea ice in a changing climate”.
What I find interesting is that although he advises me against betting on growing sea ice, he also expressly advises against betting on less. He also drops hints that there are signs pointing to possible Arctic sea ice growth ahead.
Moreover Notz confirms above that Russian oceanographer Andrey Proshutinsky, a senior scientist in the Department of Physical Oceanography at the Woods Hole Oceanographic Institution, suggests Arctic sea ice cover growth in the years ahead.
In a nutshell, while the AWI seems to have no qualms about (mis?)leading the public to believe Arctic sea ice is shrinking and that the trend will continue, other scientists clearly are no longer ready to go out on that limb.
More on this in the days ahead.
Also read: http://www.carbonbrief.org/