Arctic warming: It's not natural variability, it's all down to soot, sez Anthony Watts at WUWT

In yet another "anything but CO2" article (archived here, latest update here), Anthony Watts wants to blame all the recent warming in Greenland on soot.  He reaches left, right, up and down to get out of carbon dioxide being a greenhouse gas and warming the world. Which is pretty funny when he also tries the "I'm a reasonable man, really I am" tack by posting articles where he pretends that he really does think there is such a thing as the greenhouse effect.

What's even funnier is that Anthony is downplaying the role of natural variability in his effort to blame soot for Greenland warming.

Changes in atmospheric circulation caused some of the Arctic warming

Anthony is disputing another Nature paper, this one is about attribution of the causes of the very high amount of warming in Greenland and north eastern Canada. Going by the abstract and the press release, the authors have concluded that up to half the recent warming in Greenland and north eastern Canada may be natural variability. These areas have been warming at around 1° Celsius a decade since 1979, which is about twice that of the global average temperature rise.  The scientists have found that about half of this (0.5° Celsius a decade) is related to changes in atmospheric circulation over the North Atlantic, caused by a warmer western tropical Pacific Ocean.

From ScienceDaily.com:

The natural variations in the new study related to an unusually warm western tropical Pacific, near Papua New Guinea. Since the mid-1990s the water surface there has been about 0.3 degrees hotter than normal. Computer models show this affects the regional air pressure, setting off a stationary wave in the atmosphere that arcs in a great circle from the tropical Pacific toward Greenland before turning back over the Atlantic.

"Along this wave train there are warm spots where the air has been pushed down, and cold spots where the air has been pulled up," Wallace said. "And Greenland is in one of the warm spots."

In previous studies, Wallace and Battisti have documented the existence of decades-long climate variations in the Pacific Ocean that resemble the well-known shorter-range El Niño variations.

This particular location in the tropical Pacific may be a "sweet spot" for generating global atmospheric waves. A series of studies led by co-author Eric Steig, a UW professor of Earth and space sciences, working with Ding and Battisti, showed that waves starting in the same place but radiating southward are warming West Antarctica and melting the Pine Island Glacier.
Researchers can't say for how long the tropical Pacific will remain in this state.

"Our work shows that about half of the warming signal in Greenland comes from the predictable part -- forcing of climate by anthropogenic greenhouse gases -- but about half comes from the unpredictable part," Steig said.

The atmosphere makes the world seem small

The world is large, but studies like this show that the world isn't so large that the ocean right down near New Guinea, which is in the tropical southern hemisphere can affect the Arctic, way up north. And at the same time this same area of the Pacific is causing atmospheric waves that are warming West Antarctica and melting the Pine Island Glacier.

Anthony's sooty fixation

Anthony doesn't believe it.  He wrote about a photo of a pool of water in Greenland, which I traced back to here originally.  Anthony isn't talking about the dirty snow in the foreground. He's talking about the dark section of the pool in the shadow.

Water Filled Canyon (Greenland) Although snow has dammed outflow from the lake, nearby melt streams continue to fill sections of the canyon where snow has not accumulated.

Credit and Source: Polar Science Center, University of Washington

Anthony doesn't say how he can tell from a photograph what is causing the darker colour in the pool - whether it's dust or dirt or soot or algae or just extra deep water or all of these. Anthony Watts has done his photo-science and decided that it's definitely soot, writing:

[Note: part of the answer is in the photo they provide with the press release below, but they don't see it. - Anthony]...

...Note the black at the bottom of the melt pool, that’s carbon soot. That’s something the UW authors aren’t paying attention to....

…it has a big effect on albedo, and thus absorbed solar insolation, likely far more so than CO2 forcing, 

Another thing is, if Anthony had bothered to read the abstract and the references, he'd have noticed that the authors do indeed acknowledge that black soot does play a part in warming the Arctic (and the world). If he'd read the paper the scientists referenced, he'd have noticed that black carbon, although it does have a large effect it's not as large a forcing as CO2. As Hansen and Nazarenko wrote:

The substantial role inferred for soot in global climate does not alter the fact that greenhouse gases are the primary cause of global warming in the past century and are expected to be the largest climate forcing the rest of this century.

You may recall that Anthony has tried this argument before, misrepresenting the findings of another more recent study, which showed that the impact of soot on the Arctic depends on where it comes from. If it comes from the Arctic itself it will have a bigger impact than if it comes from the mid-latitudes. ("The Arctic surface temperature is almost 5 times more sensitive to black carbon emitted from within the Arctic than to emissions from mid-latitudes.")

Since I started this article, Anthony has added another photo showing how the albedo on Greenland has changed over the years. Thing is, it's not just dirt and dust and soot that causes the surface to become darker. As it states in the NASA article that Anthony refers to, it's not just soot:

Climate scientists have long expected that Earth’s icy North would become less reflective as global temperatures rose. Rising temperatures melt snow and ice. The uncovered terrain is darker—ocean water, vegetation, bare ground—so the area absorbs more sunlight than it used to, leading to more warming, which causes more melting. In short, the loss of reflectiveness amplifies the initial warming. This feedback is underway on Greenland’s ice, especially since 2006, a year that marks a fundamental shift toward a warmer, greener Arctic, according to the Arctic Report Card.

...The darkening in the non-melting areas, says Dr. Box, is due to changes in the shape and size of the ice crystals in the snowpack as its temperature rises. Snow grains clump together, and they reflect less light than the many-faceted, smaller crystals. Additional heat rounds the sharp edges of the crystals. Round particles absorb more sunlight than jagged ones do. 

Here is a chart showing overall contributions of humans to global warming. CO2 is by far the biggest followed by methane, but soot plays quite an important role as well. Click for larger view.

Figure TS.7 Radiative forcing of climate change during the industrial era shown by emitted components from 1750 to 2011. Source: IPCC AR5 WG1

A couple of other points. Anthony wants to blame the hotter Greenland and north eastern Canada on soot. What about the rest of the Arctic? Is soot not falling there? And is there more soot falling in the Arctic now than it did in the past?  I don't know the answer to those questions, but from what I've read there isn't any more soot being produced than there was in the past. If anything, it's decreasing.

The really weird thing is that in his focus on soot (much of which comes from human activity), Anthony is downplaying the role of natural variability in the recent rapid warming of Greenland and north eastern Canada, which is what the paper was all about after all.

From the WUWT comments

Surprisingly a lot of people are quizzing Anthony on his interpretation of the photograph he showed above. He's not having a good day.

Francisco Fernandez thinks that we should have all perished by now. He's quite impatient and has no concept of geological time scales when he says:

May 8, 2014 at 7:35 am
What I don’t get is, with all this modelling and VERY (sarc) high climate sensitivity, how is it that there’s still life on earth?

Wouldn’t the extintion of the dinosaurs, due to a catastrophic event that obliterated the species, would have caused more damage than mere CO2 <0.04%v/v?

Now, I am not sure if the dinosaur extintion due to the meteorite is a fact or theory. But if it is a fact, shouldn't it shed some light on how resilent the climate is?

steveta_uk thinks the study means he doesn't have to be concerned about global warming and says:

May 8, 2014 at 7:36 am
If they’re right, and 1/2 the warming is natural, then that about agrees with the recent lower estimates for sensitivity, and means that the expected 1.5C warming by 2100 is nothing to panic about.
So Steig has joined us at last!

john challenges Anthony and says:

May 8, 2014 at 7:40 am
Anthony, is it ALL carbon soot? Does wind blown glacial dust, or atmospheric dust, also take on a dark color when submerged? Not disagreeing about albedo effect, just wondering if carbon is the only source of dark coloration at the bottom of a melt pool on a glacier.

Billy Liar also challenges Anthony and says:

May 8, 2014 at 7:47 am
Can someone point to a chemical analysis of the black stuff in that Greenland pond?
I’m sceptical that it is ‘soot’. Oh, and where does the red stuff that you see over arctic glaciers occasionally come from?

When Paul Woland compliments Anthony for posting an article from Nature, Anthony sticks to his photo-science:

May 8, 2014 at 7:48 am
Well done WUWT for finally starting to publish research papers that, like virtually all climate-related papers in Nature, attests to the reality of significant temperature increases caused by carbon dioxide emissions.

REPLY: So like the authors of the paper, you missed what was in the photo too? – Anthony

SIGINT EX quibbles with Anthony, but Anthony is sticking to his guns:

May 8, 2014 at 8:15 am
No soot in the pool ! Just a photograph, low sun angle, shadow and diminished illumination against a very bright foreground on top ! Particulate measured in Firn and glacier ice is at the ppm level. Not enough to make a difference.

REPLY: No, sorry, you are wrong. It’s soot, dust, etc. people have sampled the bottom of those pools. Read the links provided before inserting foot in mouth. See map I’m adding from NASA showing deposition – Anthony

Neil says:

May 8, 2014 at 8:15 am
Stupid question: how do you know it’s soot and not some dark tunnel carved into the ice?

richard says:

May 8, 2014 at 8:27 am
To me the dark part looks like a deeper part of the water, i notice that there are no darker parts elsewhere or if it is does the movement of water carry it to one part.

The bottom of the picture shows discoloration of the snow- soot? that has melted and yet everywhere else looks pristine. 

Shawn in High River doesn't realise that the scientists have crunched the numbers and says:

May 8, 2014 at 8:44 am
How do they know that exactly half is due to AGW and the other half is the unpredictable part? How did they come up with that figure of 50% AGW ?

hunter confuses Greenland and north eastern Canada with the entire world when he says:

May 8, 2014 at 8:58 am
In a sense they are back peddling from the apocalypse. Now it is only 50% due to evil humans. Last year it was all human CO2. Is it due to highconfidence that the AGW believers have ‘won’ and will see their self-serviing policies imposed no matter the facts?

Steven Mosher becomes a bit impatient with Anthony Watts and his fake sceptics and says:

May 8, 2014 at 9:39 am
“Neil says: May 8, 2014 at 8:15 am Stupid question: how do you know it’s soot and not some dark tunnel carved into the ice?

1. There is no evidence that this photo shows soot.
2. Its assumed and asserted as fact.
3. Note the lack of skepticism about this “evidence”

That said, soot plays a role. thats part of the human forcing equation.
If you want to know how much of a role soot plays you have to run a GCM.
or you can just speculate and assert that it plays a major role.

Science: build a tool to try to understand the role of soot.

Politics: assert that its all down to soot. no comprehensive data, no methods, a few pictures, no testing of the hypothesis.. just assertion.

Doug Proctor also thinks that Greenland is the whole world and says:

May 8, 2014 at 9:55 am
To say that half is natural, not human-caused, is to say that you are a denier (of consensus, IPCC science). It is to say that any action to reduce human generated CO2 will have half the effect of the IPCC scenarios, and kill both the economics and the actual result of what is proposed “must” happen. 

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Qinghua Ding, John M. Wallace, David S. Battisti, Eric J. Steig, Ailie J. E. Gallant, Hyung-Jin Kim, Lei Geng. Tropical forcing of the recent rapid Arctic warming in northeastern Canada and Greenland. Nature, 2014; 509 (7499): 209 DOI: 10.1038/nature13260

Hansen, James, and Larissa Nazarenko. "Soot climate forcing via snow and ice albedos." Proceedings of the National Academy of Sciences of the United States of America 101, no. 2 (2004): 423-428. doi: 10.1073/pnas.2237157100

Sand, M., T. K. Berntsen, Ø. Seland, and J. E. Kristjánsson (2013), Arctic surface temperature change to emissions of black carbon within Arctic or midlatitudes, J. Geophys. Res. Atmos., 118, doi:10.1002/jgrd.50613.