Wondering Willis "I'm Wonderful" Eschenbach has decided to join the "ice age cometh" deniers at WUWT. Willis doesn't read scientific papers. He prefers to "wonder" about stuff. Today he's wondering about the next ice age and he says he's going to watch the snow cover to see when it's going to arrive. He writes (archived here):
So … would it not be truly ironic if pollution, in the form of soot and brown carbon, were all that has been holding off another ice age? And wouldn’t it be a cosmic joke if our efforts to clean up soot and brown carbon pollution were the straw that broke the back of the Holocene, and ushered in the new ice age?Well, it would not only be ironic, it would be pretty near impossible for earth to enter an ice age this side of 50,000 years ahead, save a massive nuclear war or a few super volcanic eruptions.
An ice age isn't due for at least 50,000 years, even without AGW
If Willis had bothered to read any science he might have come across this paper from Berger and Loutre in Science. They calculate that even without global warming, Earth wouldn't start getting cold for at least another 50,000 years. That's because of the calculated insolation in future years. Here is a diagram from their paper:
Black soot and global warming
How much does soot contribute to global warming? The IPCC AR5 WG1 Technical Summary has a chart that shows what contributes what. I've highlighted black carbon. You can see it makes quite a contribution but nothing like as much as CO2 or CH4.:
|Source: IPCC AR5 WG1 Technical Summary|
Just so you know, the IPCC report states on page TS-20 that the radiative forcing from black carbon on snow and ice is around 0.04 (0.02 to 0.09) Wm-2, compared to well-mixed greenhouse gases, which exert a forcing of 2.83 (2.54 to 3.12) Wm-2. So even if we were able to stop all black carbon from reaching the snow, it wouldn't make that much difference globally.
On black carbon, some of you might remember the article that showed that black carbon from mid-latitudes doesn't have much effect on the Arctic compared to black carbon from the far north. This is because when the soot comes from the Arctic itself, it stays at low altitude and gets deposited on the snow and ice.
Northern Hemisphere snow cover is declining in spring
Willis has also put up some charts of snow cover. The ones he chose don't tell much of a story. If he'd wanted to, he could have put up something like northern hemisphere snow cover on a seasonal basis, which would have been more informative. Notice the change in spring cover compared to the other seasons in the animation below:
|Source: Rutgers University Global Snow Lab|
Maybe after being called out by Roy Spencer recently, Wondering Willis has decided he might as well give up trying to impress scientific types. He's hoping to be fêted by the "ice age cometh" brigade at WUWT.
In the comments Willis proves that he doesn't read science by writing (excerpt):
October 18, 2013 at 11:33 am
By all astronomical Milankovitch calculations, we should be falling back into an ice age somewhere around now. To date there’s no sign of it, which is good … but there’s always tomorrow.
And more here from Wondering Willis (excerpt):
October 18, 2013 at 12:38
Now, when I look at that, I say “Yikes! We could have another ice age at any time”. In part it’s the length of the Holocene, and in part it’s that the other interglacials rose to a peak temperature … and very soon thereafter, they started dropping quickly to glacial temperatures.
The Holocene, on the other hand, rose to a peak, but has only been dropping very slowly. It has maintained a fairly flat plateau for a long, long time now. I see nothing in the historical record to indicate that we couldn’t enter another ice age tomorrow …
To add, in Willis' article he is wondering about albedo and surface temperature. His chart and wonderings look wonky but I haven't paid that part of his article any attention (archived here).
Berger, A., and M. F. Loutre. "An exceptionally long interglacial ahead?" Science 297.5585 (2002): 1287. DOI: 10.1126/science.1076120