Pollution controls have contributed to a more transparent atmosphere, thus allowing for “…a staggering increase in surface solar radiation of the order of ∼20% over the last decade.”
A new paper (O’Dowd et al.) from the National University of Ireland presented this summer at the 19th International Conference on Nucleation and Atmospheric Aerosols suggests that clean air laws put in place in the 1970’s and 80’s have resulted in an increase in sunlight impacting the surface of the Earth, and thus have increased surface temperatures as a result. In one fell swoop, this can explain why surface temperature dipped in the 1970’s, prompting fears of an ice age, followed by concerns of global warming as the air got cleaner after pollution laws and controls were put in place.
WUWT covered a similar effort (Wild 2009) here and paper here (PDF 1.4 mb) which showed the issue but fell short of showing a provable causation for temperature.
Now with this new effort by O’Dowd et al., it seems quite likely that cleaner air is in fact allowing in more solar radiation to the surface, and thus increasing surface temperatures by that increase of insolation.
Wild 2012, was a follow up, and figure 1 above is from that paper.
Martin Wild, 2012, Institute for Atmospheric and Climate Science, Zurich, Switzerland. Published in BAMS: Enlightening Global Dimming and Brightening
http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-11-00074.1 (open PDF)
Now with O’Dowd et al. and their findings, this “global brightening” as a climate driver is looking much more plausible.
The authors write in the new O’Dowd paper:
This study has demonstrated for the first time, using in-situ PM measurements, that reducing aerosol pollution is driving the Insolation Brightening phenomenon and that the trends in aerosol pollution, particularly for sulphate aerosol, is directly linked to anthropogenic emissions. Ultimately, the analysis demonstrates that clean air policies in developed regions such as Europe are driving brightening of the atmosphere and increasing the amount of global radiation reaching the Earth’s surface. The actual impact of cleaner air and insolation brightening on temperature remains to be elucidated.
And offer this graph:
This is inline with Hatzianastassiou et al., 2012, Features and causes of recent surface solar radiation dimming and brightening patterns:
Surface incident solar radiation has been widely observed since the late 1950s. Such observations have suggested a widespread decrease between the 1950s and 1980s (“global dimming”) and a reverse brightening afterward.
http://adsabs.harvard.edu/abs/2012EGUGA..1413344H
The new O’Dowd paper:
Cleaner air: Brightening the pollution perspective?
AIP Conf. Proc. 1527, pp. 579-582; doi:http://dx.doi.org/10.1063/1.4803337 (4 pages)
Abstract:
Clean-air policies in developing countries have resulted in reduced levels of anthropogenic atmospheric aerosol pollution. Reductions in aerosol pollution is thought to result in a reduction in haze and cloud layers, leading to an increase in the amount of solar radiation reaching the surface, and ultimately, an increase in surface temperatures. There have been many studies illustrating coherent relationships between surface solar radiation and temperature however, a direct link between aerosol emissions, concentrations, and surface radiation has not been demonstrated to date. Here, we illustrate a coherence between the trends of reducing anthropogenic aerosol emissions and concentrations, at the interface between the North-East Atlantic and western-Europe, leading to a staggering increase in surface solar radiation of the order of ∼20% over the last decade.
h/t to Sunshine Hours
It seems like a possible case of Occam’s Razor in action – the simplest explanation is the most likely.
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The avg ignorant warmer would just use this to justify EPA expansionism. They think CO2 is just another pollutant.
Pamela Gray says: @ur momisugly August 20, 2013 at 8:14 am
Re: New York Times article By JUSTIN GILLIS
Published: August 19, 2013
Notice the slight of hand change from “increasing” climate extremes to “changing” climate extremes….
So now we have the bottom line. Humans cause bad weather. We have made a complete turn around back to caveman days when lightening was a sign from the gods that we have done something wrong. Quick! Find a virgin!
>>>>>>>>>>>>>>>>>>
Or Burn that Witch!
Unfortunately we are the ‘Witches’
If you can not blame humans you can not scare them into changing their behavior and demanding homage and indulgences (taxes) be paid.
This sounds like more of the same, the weather is bad humans are to blame, crap. Is there some truth in it? Probably but as with the CO2 scare the truth is a tiny kernel wrapped in propaganda and distortions.
The CO2 propaganda is getting quite a bit ragged around the edges and this helps prop it back up. The Climate modes were off because we left out Human Caused aerosols. Heck you can even blame the Dust Bowl on humans. Remember the farm dust which the EPA now wants to regulate.
MattN says: “I remember this scenario being discussed years ago here at WUWT. Not sure how much I buy it. 20% is a whole lot.”
I agree with MattN and Michael Hart and Geo Smith and many others, above. The 20% figure doesn’t pass the sniff test. Way too much compared to my sight test and other personal observations. I, too, as per Richard M, was thinking of Bob Tisdale’s work in this context. I just can’t subscribe to the theory.
But the science isn’t settled yet, is it?
One of the problems with trying to PROVE a correlation between cleaner/dirtier air and more sunshine/less sunshine is the lack of data. I’ll use Canada as an example. There used to be over 250 stations collecting bright sunshine data in 1970. Now there are 7.
http://sunshinehours.wordpress.com/2012/12/08/nov-2012-canada-only-7-stations-collecting-sunshine-data/
“The 20% figure doesn’t pass the sniff test. ”
Spain. 6.5W/m2 per decade increase in summer sunshine from 1985-2010 .
A doubling of CO2 is supposedly only 3.7W/m2.
http://sunshinehours.wordpress.com/2012/11/30/sunshine-up-in-spain-from-1985-to-2010-by-3-9wm2/
Switzerland
http://sunshinehours.wordpress.com/2012/09/25/sunshine-up-in-switzerland-sinc-the-1980s/
UK
In the mid 2000s, the anomaly was 9.48 hours more sunshine per month.
Thats over 100 extra hours per year in a country that gets around 1400 hours. 7% averaged over the whole year.
http://sunshinehours.wordpress.com/2012/07/02/uk-met-bright-sunshine-5-year-averages-plotted-using-all-monthly-anomalies/
tonybclimatereason says:
August 19, 2013 at 11:14 pm
Thanks for the link to the “Beautiful Smog” article by Karlins.
Such things are fascinating in their connections of history, art, geography, and atmospheric aspects. There was a well done one for “The Scream” that I cannot now find. Here is another but more condensed version:
http://voices.yahoo.com/the-volcanic-explosion-krakatoa-influenced-edvard-1406579.html?cat=37
tonyb says:
“Here is London weather. seems to be on the cool side in 1952. The smog was very ,localised and Greenwich due to its height/location may have missed it.
http://www.london-weather.eu/category.46.html”
Well it was a warm dry Summer in London like much of the country, but what I should have done was research the smog, which appears to be a freezing fog from the 5-9th December:
http://en.wikipedia.org/wiki/Great_Smog
http://www.tutiempo.net/en/Climate/Londres_Heathrow_Airport/12-1952/37720.htm
sunshinehours1 says:
August 19, 2013 at 10:02 pm
Mike Abbott says: “Wild is clearly in the AGW/GHG camp.”
Wild pays lip service to AGW/CO2 in order to prevent his funding from being cut off. But those statements aren’t backed up by anything in his papers.
The science in his papers contradict AGW/CO2 if you had read them.
It’s more than lip service. Dr. Wild is Associate Editor of the Journal of Geophysical Research, a publication of the American Geophysical Union. He is also a Lead Author on the IPCC’s AR5. In many interviews and publications, he expresses his belief in the enhanced GHG effect. (See http://www.iac.ethz.ch/people/wild.) I rest my case.
I think Dr. Wild would view his findings as complementing GHG theory and I see examples of that in his papers. The best example is in his detailed discussion of NH vs. SH climate model accuracy. In any case, there definitely is one glaring discrepancy: If the recent “pause” in surface temperatures can be explained by Wild’s global brightening theory, what does that say about Trenberth’s theory that the heat is hiding in the deep ocean?? It will be interesting to see how the Climate Establishment deals with that. Wild, a member of that establishment and a scientist with impeccable credentials, cannot be easily dismissed.
Mike Abbott says:
“he expresses his belief in the enhanced GHG effect.”
So do I. That doesn’t make me any less skeptical of CAGW. If these ideas hold up he is knocking a great big whole in the warming from the 1950’s being mostly due to GHG’s meme which has resulted in the high sensitivity belief among the alarmists. This in turn would make a low sensitivity much more likely than not and a high sensitivity very unlikely.
Go Dr. Wild (and keep your head down).
Mike Abbott: “he expresses his belief in the enhanced GHG effect”
A “belief” is no substitute for science.
Wild’s papers are full of data and science showing changes of .5W/m2/year due to changes in surface solar radiation. Changes of that magnitude dwarf the supposed effect of CO2.
Sunshine hours
In our neck of the West Country (Torbay) we get around 1700 hours of sun per year.
There is quite a proliferation of solar farms round here as a result but this pitiful amount is of course heavily geared towards the summer.
Who (without a large subsidy) would build a 50 acre (50 acres!!!) solar farm that would barely power a torch in the winter when energy is most needed? Of course it is even more needed on a cold winters NIGHT. Wonder how the solar farms will perform then?
The Uk’s energy policy gets dafter by the minute.
tonyb
Can anyone remember “pan evaporation rates”? Is this a retooled version of the “Global Dimming” theory [who was that again?] that we were harangued with 10 years ago, explaining why the CO2 induced warming predicted had not yet come to pass and that as soon as we cleaned up our acts things would suddenly get “much worse”? On the surface of it both versions seem like plausible explanations, which one will gain the most traction with observations?
W^3
As to ‘peer review’ there is this quote, available in Wikipedia, by Richard Horten, editor of the Lancet “But we know that the system of peer review is biased, unjust, unaccountable, incomplete, easily fixed, often insulting, usually ignorant, occasionally foolish, and frequently wrong.”
GW ended before 2001. http://endofgw.blogspot.com/
AGW never was. http://climatechange90.blogspot.com/2013/05/natural-climate-change-has-been.html
I think a lot of us (including me) have been wondering along these lines for many years.
w.w.wygart says:
August 20, 2013 at 12:28 pm
“Can anyone remember “pan evaporation rates”? Is this a retooled version of the “Global Dimming” theory [who was that again?]”
I think it was Hanson who first said that air pollution would warm the surface, and then later came out with the opposite hypothesis. I would think it would depend on the altitude, if it absorbs heat near the surface, the surface warms more, if it absorbs heat further up, then the surface loses out.
Pan evaporation rates are affected by wind speed, which globally have been dropping.
Pamela Gray says:
August 20, 2013 at 8:14 am
Quick! Find a virgin!
I thought virgins had become extinct due to global warming?
Wondering home many actually read the Wild 2012 study. The caption for figure 1 above seems conveniently left out. Click on the link and read it if you haven’t. Seems the Wild study doesn’t propose that increased sunshine during the brightening period has caused the warming but rather the decreased sunshine during the dimming period masked AGW. The last statement is the most telling, “Under these perspectives, only the rapid worldwide implementation of both rigorous greenhouse gas reduction and air quality measures will allow us to minimize adverse climate and health impacts and ensure sustainable living conditions for future
generations on Earth.” When this article is put in its proper context it paints a much different picture.
Scott, I prefer earlier Wild research.
,5 Watts / m2 / year totally overwhelms the supposed CO2 signal.
http://i55.tinypic.com/34qk01z.jpg
old engineer:
Your post at August 19, 2013 at 8:15 pm
http://wattsupwiththat.com/2013/08/19/shocker-global-warming-may-simply-be-an-artifact-of-clean-air-laws/#comment-1395085
says
Sorry, but NO! That is a misunderstanding.
The GCM’s don’t “include the effects of atmospheric aerosols”. They each use a different value of assumed aerosol cooling as a ‘fiddle factor’ which compensates for each GCM using a unique – and too high – value of climate sensitivity to “green house gas effects”.
It seems I need to post the following yet again.
None of the models – not one of them – could match the change in mean global temperature over the past century if it did not utilise a unique value of assumed cooling from aerosols. So, inputting actual values of the cooling effect (such as the determination by Penner et al.
http://www.pnas.org/content/early/2011/07/25/1018526108.full.pdf?with-ds=yes )
would make every climate model provide a mismatch of the global warming it hindcasts and the observed global warming for the twentieth century.
This mismatch would occur because all the global climate models and energy balance models are known to provide indications which are based on
1.
the assumed degree of forcings resulting from human activity that produce warming
and
2.
the assumed degree of anthropogenic aerosol cooling input to each model as a ‘fiddle factor’ to obtain agreement between past average global temperature and the model’s indications of average global temperature.
More than a decade ago I published a peer-reviewed paper that showed the UK’s Hadley Centre general circulation model (GCM) could not model climate and only obtained agreement between past average global temperature and the model’s indications of average global temperature by forcing the agreement with an input of assumed anthropogenic aerosol cooling.
The input of assumed anthropogenic aerosol cooling is needed because the model ‘ran hot’; i.e. it showed an amount and a rate of global warming which was greater than was observed over the twentieth century. This failure of the model was compensated by the input of assumed anthropogenic aerosol cooling.
And my paper demonstrated that the assumption of aerosol effects being responsible for the model’s failure was incorrect.
(ref. Courtney RS An assessment of validation experiments conducted on computer models of global climate using the general circulation model of the UK’s Hadley Centre Energy & Environment, Volume 10, Number 5, pp. 491-502, September 1999).
More recently, in 2007, Kiehle published a paper that assessed 9 GCMs and two energy balance models.
(ref. Kiehl JT,Twentieth century climate model response and climate sensitivity. GRL vol.. 34, L22710, doi:10.1029/2007GL031383, 2007).
Kiehl found the same as my paper except that each model he assessed used a different aerosol ‘fix’ from every other model. This is because they all ‘run hot’ but they each ‘run hot’ to a different degree.
He says in his paper:
Iimportantly, Kiehl’s paper says:
And the “magnitude of applied anthropogenic total forcing” is fixed in each model by the input value of aerosol forcing.
Thanks to Bill Illis, Kiehl’s Figure 2 can be seen at
http://img36.imageshack.us/img36/8167/kiehl2007figure2.png
Please note that the Figure is for 9 GCMs and 2 energy balance models, and its title is:
It shows that
(a) each model uses a different value for “Total anthropogenic forcing” that is in the range 0.80 W/m^-2 to 2.02 W/m^-2
but
(b) each model is forced to agree with the rate of past warming by using a different value for “Aerosol forcing” that is in the range -1.42 W/m^-2 to -0.60 W/m^-2.
In other words the models use values of “Total anthropogenic forcing” that differ by a factor of more than 2.5 and they are ‘adjusted’ by using values of assumed “Aerosol forcing” that differ by a factor of 2.4.
So, each climate model emulates a different climate system. Hence, at most only one of them emulates the climate system of the real Earth because there is only one Earth. And the fact that they each ‘run hot’ unless fiddled by use of a completely arbitrary ‘aerosol cooling’ strongly suggests that none of them emulates the climate system of the real Earth.
Richard
Theo Goodwin:
re your post at August 19, 2013 at 8:58 pm.
Yes, I have made a long post which explains your correct point, but – for some unknown reason – it is waiting in moderation.
Richard
20% ! That’s a sabre-tooth in the living room. Dinner is served!
Seems to me that aerosols aren’t THE answer but they are certainly part of it, along with many of the things we discuss here. My take is that the effect of aerosols is a suitable candidate for more research.
Are the basic ideas about the aerosol loading correct? I think the natural aerosol loading is incorrectly estimated!
According to Natalie Mahowald, the amount of dust in the Earth’s atmosphere has doubled over the last century.
http://www.enn.com/sci-tech/article/42210
http://www.sciencedaily.com/releases/2011/01/110110055748.htm
According to Jasper Kok, (who carries out interesting research on dust aerosol)
http://www.wired.com/wiredscience/2010/12/dust-shatters-like-glass/
Global Circulation Models overestimate the amount of cooling dust by a large factor. And do not account for warming silts!!!
http://sitemaker.umich.edu/jasperkok/files/kok2011_pnas_scalingtheorydustpsd.pdf
“Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust.”
“… On a global scale, the dust cycle in most GCMs is
tuned to match radiative measurements, !!!
such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought.”
Have they corrected GCMs to account for silts?
So what is it. If they are guessing (tuning to match) the cooling effect of a loading of dust is there more warming from, dark, silt aerosol (missing) or too much emphasis on cooling clay aerosol or is there more dust than they think? (fertiliser)
Has there been an ever increasing amount (getting dustier over the last century) of ‘missed’ silt aerosol which would have a radiative warming effect?