Tuesday, November 12, 2013

Anthony Watts gets it wrong again, this time with CFCs

Sou | 3:30 PM One comment so far. Add a comment

Anthony Watts, who runs an anti-science blog known as WUWT, thinks he has found more science to mock.  As usual, whenever he attempts to write an article himself he stuffs it up.  He writes (archived here):
Busted messaging: CFC’s cause warming AND cooling
From the make up your freaking minds department comes this oopsy juxtaposition of alarmist messaging.
In an attempt to explain “the pause”, researchers are now grasping for explanations:
Anthony mucks it up - again!  It's he who can't figure out the science.

Statistical derivation of human influences on global temperature in the twentieth century

Anthony is writing about a new paper in Nature by Francesco Estrada et al that explored factors operating during the twentieth century and their impact on earth's climate.

According to the associated article in Nature News, Estrada13, using a statistical approach rather than a climate model, found that cooling of the surface temperature was associated with reductions in greenhouse gas emissions associated with economic downturns.  They also found that if it weren't for the Montreal Protocol, earth would be warmer still.  However just how much warmer it would be is disputed.  Maybe not as much as the Nature paper suggests.  Probably about 0.1°C.  (I don't have a copy of the paper so I don't know the numbers they've worked out.)  From the Nature News article (my bold italics):
A cooling period between 1940 and 1970 had previously been chalked up to natural variability and the Sun-shielding effect of pollution emitted by European industries, as they recovered after the Second World War. But Estrada and his colleagues found that it folllowed a reduction in greenhouse-gas emissions associated with economic downturns, when industries were less active. Significant drops in emissions occurred during the First World War, the Great Depression of the 1930s and the Second World War....
...For the 1940-70 period, the way the paper shows how economic factors drove emissions down is “very nice,” says Ross Salawitch, an atmospheric scientist at the University of Maryland in College Park. “It hits the sweet spot.”
Warming has also eased off since the mid-1990s. Estrada's study links that to the 1987 Montreal Protocol that banned the release of CFCs — once used widely in refrigerants, solvents and propellants — to stop ozone depletion, which allowed more warming solar radiation to reach Earth. Temperatures today might have been 0.1 °C warmer had CFC emissions continued unabated, according to a commentary to be published alongside the study.
“Without the Montreal Protocol, we’d be warmer than we are now,” agrees Salawitch. “But I question whether the recent pause in global warming is due to that.” Estrada's study would be stronger had it also considered changes in ocean heat uptake and aerosol cooling, he says.

The headline of the Nature article (not the paper itself) reads: Ozone-hole treaty slowed global warming.  I'm probably picking nits, but I think that headline is misleading.  The sub-headline is better.  It reads: Montreal Protocol helped to curb climate change and so did world wars and the Great Depression.

The take-away message from the abstract is this one:
We conclude that reductions in greenhouse gas emissions are effective in slowing the rate of warming in the short term.
If they are correct, and what I've read elsewhere would seem to indicate they are, then action to cut emissions would slow warming perceptibly.  Maybe even on timescales suited to the political calendar.  No, it won't start to cool down but it won't warm up as quickly as it otherwise would.  It would be good if we cut emissions by shifting to clean energy and didn't wait for another GFC or Depression.  (If we don't do it ourselves then I'll bet that nature itself will force our hand and probably sooner rather than later.)

Where Anthony goes wrong...

Back to Anthony Watts.  What Anthony did was dig out a Science Daily article about a 2010 paper by Korhonen et al.  He picked out a line that said that Antarctica was not as warm as it might have been because of the closing ozone hole.  Closing the hole in the ozone layer led to high speed winds which caused summer-time clouds to form.  These clouds reflected more of the sun and shielded the Antarctic from warming.  This is what Anthony pointed to:
The Antarctic ozone hole was once regarded as one of the biggest environmental threats, but the discovery of a previously undiscovered feedback shows that it has instead helped to shield this region from carbon-induced warming over the past two decades.

Anthony's reasoning is probably fair enough for a science illiterate as far as it goes.  The article does discuss the impact of the ozone hole on constraining warming - if only in southern latitudes (50-65°S is mentioned in the paper itself).  But Anthony's attention span is seriously limited as we shall see later on.

Summer clouds over Antarctica are more reflective because of the ozone hole

Here is what was in Anthony's second paper.  If you are easily confused about feedbacks and forcings, I suggest skipping this next bit.  The paper seems to be a bit inconsistent in the use of these terms, but maybe that's just the way I'm reading it.  The difficulty arises because the paper is discussing two different but connected forcings:-  greenhouse gas forcing (positive) and ozone loss forcing (negative) - which act in concert to affect the polar winds.

First of all, in the abstract of the paper the authors talk of the increase in cloud reflectivity in terms of it "acting against that from greenhouse gas forcing over the same time period, and thus represent(ing) a substantial negative climate feedback".  It's not causing cooling.  It's dampening the greenhouse gas forcing.  However later in the paper it describes the impact in terms of being a positive feedback to the negative forcing from stratospheric ozone loss.  As I understand it the authors are talking about two different things.  One is greenhouse gas forcing.  The other is ozone forcing.  These act together in the Antarctic to alter the circulation of the atmosphere.  So it's all quite complicated.  The discussion section of the paper states (my bold italics):
The calculated changes in SH aerosol represent a potentially important climate feedback in which anthropogenic emissions of greenhouse gases and ozone depleting substances alter the circulation of the atmosphere [Thompson and Solomon, 2002], which in turn induces greater emissions of sea spray that cause a negative radiative forcing through higher cloud drop concentrations in low level clouds. The annual mean positive forcing from all well mixed greenhouse gases at these latitudes (50 – 65S) is 1Wm2 over the two decades studied [Forster et al., 2007]. The only other important forcing at southern high latitudes is stratospheric ozone loss, the annual average of which has been estimated to be approximately 0.5 W m2 since the late 1970s [Forster and Shine, 1997]. Thus, during the summer season over high latitude ocean the feedback on low level clouds through wind intensification (0.7 W/m2) together with ozone loss may have cancelled out the positive greenhouse gas forcing since the 1980s....
... The implications for future climate need to be evaluated. If, as recently suggested [Son et al., 2008], ozone depletion is the primary cause of wind speed increases, then this cloud forcing acts as a positive feedback on the ozone induced cooling. It more than doubles the negative radiative forcing from stratospheric ozone loss and suggests that future ozone recovery would cause a positive radiative forcing.

Back to Anthony again.  Strangely enough, Anthony seemed to have missed the headline to that article, which was:

Ozone Hole Healing Could Cause Further Climate Warming

Yes.  That's right.  In his zeal to find something wrong with the science, Anthony skipped over the headline saying that as the ozone hole heals, Antarctica will warm.  He ignored the thrust of the article and instead he went straight to one of the paragraphs in the text.  He also seems to have missed reading the rest of that article, in which was written:
"If, as seems likely, these winds die down, rising CO2 emissions could then cause the warming of the southern hemisphere to accelerate, which would have an impact on future climate predictions," he added.
As I wrote in the feedback/forcing section above, the Science Daily article goes on to explain that the high speed winds whip up sea spray and tiny salt particles, which eventually form part of the clouds, making them more reflective.  As the ozone layer recovers that particular feedback mechanism could slow or even reverse, leading to accelerated warming in Antarctica.  This means that any dampening of warming by CFCs effect on the ozone hole and cloud formation would disappear.  However CFCs remaining in the atmosphere will still have their greenhouse gas properties and add to global warming, albeit not hugely (provided we don't increase them).

CFCs and global warming

Of course the Nature article wasn't referring to clouds over southern oceans.  It was referring to the global effect of the reduction of CFCs in the atmosphere following the Montreal Protocol.

CFCs do contribute to global warming, but nothing like what CO2 contributes.  The AR5 WG1 IPCC report states on page TS-19, for example (my bold and italics):
Atmospheric N2O has increased by 6% since AR4 causing a RF of 0.17 [0.15 to 0.19] W m–2. N2O concentrations continue to rise while those of CFC-12, the third largest WMGHG (well-mixed greenhouse gas) contributor to RF for several decades, are decreasing due to phase-out of emissions of this chemical under the Montreal Protocol. N2O is now likely the third largest WMGHG contributor to RF. The RF from halocarbons is very similar to the value in AR4, with a reduced RF from CFCs but increases in many of their replacements. Four of the halocarbons (CFC-11, CFC-12, CFC-113, and HCFC-22) account for 85% of the total halocarbon RF. The former three compounds have declining RF over the last five years but are more than compensated for by the increased RF from HCFC-22. There is high confidence that the growth rate in RF from all WMGHG is weaker over the last decade than in the 1970s and 1980s owing to a slower increase in the non-CO2 RF.

And on page 2-11, the report states:
Atmospheric HFC abundances are low and their contribution to radiative forcing is small relative to the CFCs and HCFCs they replace (less than 1% of the total by well-mixed greenhouse gases; Chapter 8). As they replace CFCs and HCFCs phased out by the Montreal Protocol, however, their contribution to future climate forcing is projected to grow considerably in the absence of controls on global production (Velders et al., 2009).
There is more in the report on CFCs and their replacements.

The crux of the matter is that although the Montreal Protocol had the effect of reducing CFCs, the replacement halocarbons are adding to radiative forcing.

The IPCC report has a diagram on page TS-91 showing the relative contribution of different components of radiative forcing. (Click for larger view.)

Source: IPCC AR5 WG1 Fig TS-7

Anthony Watts doesn't know where he is going

Anthony Watts closed his article with the following:
I don’t think anybody really knows which way it is going.
Well, that may be so.  It certainly looks as if Anthony Watts doesn't have a clue.

As for "which way it's going", it depends on what action we take in regard to all the gunk we throw into the air.  However scientists do know that some gases cause warming.  And they do know that halocarbons in the main cause more warming than cooling.  What happens to the winds in Antarctica as the ozone hole closes is probably still to be determined.  But if the winds slow down and stop whipping up sea water as much as they've been doing, then it's on the cards that southern regions of the globe will be in for a fair bit of warming.

Francisco Estrada, Pierre Perron and Benjamin Martínez-López (2013) Statistically derived contributions of diverse human influences to twentieth-century temperature changes, Nature Geoscience (2013) doi:10.1038/ngeo1999

Korhonen, H., K. S. Carslaw, P. M. Forster, S. Mikkonen, N. D. Gordon, and H. Kokkola (2010), Aerosol climate feedback due to decadal increases in Southern Hemisphere wind speeds, Geophys. Res. Lett., 37, L02805, doi:10.1029/2009GL041320.

From the WUWT comments

The illiterati is out in full force at WUWT - archived here.

pinroot points out that Anthony didn't remember he's already posted a (suspect) article (archived here and disputed here) about CFCs and warming and says:
November 11, 2013 at 4:21 pm
There was this from late May, which claimed to show a link between CFC levels and warming:
So now there are at least two papers linking CFC’s with warming. That’s a consensus, right? ;)

Rhoda R hasn't even scratched the surface when it comes to climate science and says:
November 11, 2013 at 4:47 pm
Frankly, until they can explain why the world goes into and out of ice ages AND then can show that what is going on now is unique, then, and only then, will I buy into man-made climate anything.
Bruce Cobb joins in the illiterati chorus and says:
November 11, 2013 at 4:48 pm
Oh look! Bright, shiny new climate control knobs to play with on their dial- o-climate contraption.
alexwade takes the opportunity to show off his ignorance too and says:
November 11, 2013 at 5:05 pm
There is a simple answer for all this: Somehow, someway for every bad event that happens, we are at fault. So now surrender your rights and pay up. P.S. I, the enlightened telling you this, don’t have to pay and will still have full rights.
When you remember that is how environmentalists think, then nothing is a contradiction.
I am reminded of an old saying: “Jesus, save me from your followers.” Although I do not believe in “Mother Earth” or Gaia or anything like that, we could just as well re-word that saying as “Mother Earth, save us from your followers.”

ROM joins in and says:
November 11, 2013 at 5:28 pm
This is what you get when the inmates get to running the climate change mental asylum.
Or as an old saying goes and this is ever more applicable to climate change science and scientists. “Some minds are like concrete. All mixed up and set hard”.

Bryan A says:
November 11, 2013 at 6:12 pm
Must be the latest “Hypothesis de-jour”
They did need something to explain the Antarctic ice extent increase that would blend in with the Global Climate Scare MEME

p@ Dolan is really flying with illiterati wisdom and , with lots of "ilks" and "well saids" says (and this is but an extract from an overly long comment):
November 11, 2013 at 7:15 pm
@Rhoda R says: November 11, 2013 at 4:47 pm
Frankly, until they can explain why the world goes into and out of ice ages AND then can show that what is going on now is unique, then, and only then, will I buy into man-made climate anything.
Applause! Well said!
@geran says: November 11, 2013 at 5:53 pm
Based on the abstract, this might be the funniest paper ever submitted.
“Here we analyse radiative forcing and temperature time series with state-of-the-art statistical methods to address this question without climate model simulations.”
Give ‘em props, man: they DID, after all, try to do it WITHOUT the Great and Powerful Oz. The rest of their ilk are programming their own prejudices and liberal self-hatred into computer models and then statistically measuring their results against similar idiotic programs, and claiming that their conclusions have some basis in reality…obviously never heard the old computer term GIGO…
@Jimbo says: November 11, 2013 at 5:51 pm
By the way Pippen Kool, how do you know the Ozone hole hasn’t always been there? The hole was discovered in 1985.
Way to GO! I’m amazed at all these folks who assume that CFCs actually caused something they only discovered a short while ago, have no idea when it first occurred, or if it had been there since the dawn of time for all they knew, and THEN have the audacity to claim that their treaty to reduce CFCs is what’s responsible for it’s reduction in size, when they have yet to prove that’s the cause!

Are you all suitable amazed and impressed at p@ Dolan's cleverness and insight?  Wait! there's more archived here (if you have the stomach for it).

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