Another January, another annual data point.
As in years past, the annual rollout of the GISTEMP, NOAA, HadCRUT and Berkeley Earth analyses of the surface temperature record have brought forth many stories about the long term trends and specific events of 2022 – mostly focused on the impacts of the (ongoing) La Niña event and the litany of weather extremes (UK and elsewhere having record years, intense rainfall and flooding, Hurricane Ian, etc. etc.).
But there are a few things that don’t get covered much in the mainstream stories, and so we can dig into them a bit here.
What influence does ENSO really have?
It’s well known (among readers here, I assume), that ENSO influences the interannual variability of the climate system and the annual mean temperatures. El Niño events enhance global warming (as in 1998, 2010, 2016 etc.) and La Niña events (2011, 2018, 2021, 2022 etc.) impart a slight cooling.
Consequently, a line drawn from an El Niño year to a subsequent La Niña year will almost always show a cooling – a fact well known to the climate disinformers (though they are not so quick to show the uncertainties in such cherry picks!). For instance, the trends from 2016 to 2022 are -0.12±0.37ºC/dec but with such large uncertainties, the calculation is meaningless. Far more predictive are the long term trends which are consistently (now) above 0.2ºC/dec (and with much smaller uncertainties ±0.02ºC/dec for the last 40 years).
It’s worth exploring quantitatively what the impact is, and this is something I’ve been looking at for a while. It’s easy enough correlate the detrended annual anomalies with the ENSO index (maximum correlation is for the early spring values), and then use that regression to estimate the specific impact for any year, and to estimate an ENSO-corrected time series.
The surface temperature records are becoming more coherent
Back in 2013/2014, the differences between the surface indices (HadCRUT3, NOAA v3 and GISTEMP v3) contributed to the initial confusion related to the ‘pause’, which was seemingly evident in HadCRUT3, but not so much in the other records (see this discussion from 2015). Since then all of the series have adopted improved SST homogenization, and HadCRUT5 adopted a similar interpolation across the pole as was used in the GISTEMP products. From next month onwards, NOAA will move to v5.1 which will now incorporate Arctic buoy data (a great innovation) and also provide a spatially complete record. The consequence is that the surface instrument records will be far more coherent than they have ever been. Some differences remain pre-WW2 (lots of SST inhomogeneities to deal with) and in the 19th C (where data sparsity is a real challenge).
The structural uncertainty in satellite records is large
While the surface-based records are becoming more consistent, the various satellite records are as far apart as ever. The differences between the RSS and UAH TLT records are much larger than the spread in the surface records (indeed, they span those trends), making any claims of greater precision somewhat dubious. Similarly, the difference in the versions of the AIRS records (v6 vs. v7) of ground temperature anomalies produce quite distinct trends (in the case of AIRS v6, Nov 2022 was exceptionally cold, which was not seen in other records).
When will we reach 1.5ºC above the pre-industrial?
This was a very common question in the press interviews this week. It has a few distinct components – what is the ‘pre-industrial’ period that’s being referenced, what is the uncertainty in that baseline, and what are the differences in the long term records since then?
The latest IPCC report discusses this issue in some depth, but the basic notion is that since the impacts that are expected at 1.5ºC are derived in large part from the CMIP model simulations that have a nominal baseline of ~1850, ‘pre-industrial’ temperatures are usually assumed to be some kind of mid-19th Century average. This isn’t a universally accepted notion – Hawkins et al (2017) for instance, suggest we should use a baseline from the 18th Century – but it is one that easier to operationalise.
The baseline of 1880-1900 can be calculated for all the long temperature series, and with respect to that 2022 (or the last five years) is between 1.1 and 1.3ºC warmer (with Berkeley Earth showing the most warming). For the series that go back to 1850, the difference between 1850-1900 and 1880-1900 is 0.01 to 0.03ºC, so probably negligible for this purpose.
Linear trends since 1996 are robustly just over 0.2ºC/decade in all series, so that suggests between one and two decades are required to have the mean climate exceed 1.5ºC, that is around 2032 to 2042. The first specific year that breaches this threshold will come earlier and will likely be associated with a big El Niño. Assuming something like 2016 (a +0.11ºC effect), that implies you might see the excedence some 5 years earlier – say 2027 to 2037 (depending a little on the time-series you are following).
2023 is starting the year with a mild La Niña, which is being forecast to switch to neutral conditions by mid-year. Should we see signs of an El Niño developing towards the end of the year, that will heavily favor 2024 to be a new record, though not one that is likely to exceed 1.5ºC however you calculate it.
[Aside: In contrast to my reasoning here, the last decadal outlook from the the UK MetOffice/WMO suggested that 2024 has a 50-50 chance of exceeding 1.5ºC, some 5 or so years early than I’d suggest, and that an individual year might reach 1.7ºC above the PI in the next five years! I don’t know why this is different – it could be a larger variance associated with ENSO in their models, it could be a higher present day baseline (but I don’t think so), or a faster warming rate than the linear trend (which could relate to stronger forcings, or higher effective sensitivity). Any insight on this would be welcome!]
References
- E. Hawkins, P. Ortega, E. Suckling, A. Schurer, G. Hegerl, P. Jones, M. Joshi, T.J. Osborn, V. Masson-Delmotte, J. Mignot, P. Thorne, and G.J. van Oldenborgh, "Estimating Changes in Global Temperature since the Preindustrial Period", Bulletin of the American Meteorological Society, vol. 98, pp. 1841-1856, 2017. http://dx.doi.org/10.1175/BAMS-D-16-0007.1
Well, I am of the conviction that we ARE already at +1,5°C. The AR6 SPM has a nice picture showing a +1,5°C warming, offset by a ~-0,4°C cooling from sulphur oxide, giving the observed value of ~+1,1°C.
Whilst an El Nino event obviously causes a positive spike in global average surface temperatures, this is due to heat being transferred from the Pacific ocean to the atmosphere: ie it is a redistribution of energy rather than an increase in the total energy of the atmosphere/oceans/land surface.
Is there any estimate of how, if at all, an El Nino effects that overall energy budget?
For example, if the surface waters of parts of the Pacific (and the atmosphere), are warmer than normal during an El Nino it would be expected that they would radiate more energy to space, thus causing an overall decrease in energy. However, I suspect that changes in clouds may have a larger impact.
Do we know what that is?
@Slioch says: – ” …during an El Nino it would be expected that they would radiate more energy to space, thus causing an overall decrease in energy. However, I suspect that changes in clouds may have a larger impact.Do we know what that is? ”
ms: — I suspect the same. La Nina years can be ~0.5°C cooler as they push & hide large amounts of energy into the western Pacific, while El Nino years release more energy stored in the Pacific Ocean.
The Earth Energy Imbalance @ Top Of Atmosphere (EEI @ TOA) was close to zero W/m² (neither warming nor cooling) in 2010, also a very hot El Nino year, while in 2012, a strong El Nina year, the EEI was increased again to almost 1.5W/m².
El Nino years thus moderate the increase in global warming and are therefore more advantageous for the earth’s climate in the long term. This is IMO due to the generally higher relative humidity (RH) of El Ninos. In the graph of the Met Office for RH you can recognize the El Nino years 1998, 2010, 2016 by the maximum peaks.
https://climate.metoffice.cloud/dashfigs/humidity_RH.png
https://pub.mdpi-res.com/atmosphere/atmosphere-12-01297/article_deploy/html/images/atmosphere-12-01297-g004.png?1634310863
I am convinced that the falling trend in RH (with a slight increase in absolute humidity) is primarily due to the steady accumulated loss of evaporative landscapes, the desertification & land use change and this is therefore also responsible for a declining cloud albedo, which @ TOA is responsible for much of the increasing EEI & global warming trend. I have described this in more detail on my website.
https://climateprotectionhardware.wordpress.com/
Have you heard of the exotic but interesting hypothesis that some of the global warming is generated by the undersea volcanoes, the “ring of fire” under the Pacific Ocean, and brought to the ocean surface from time to time by the El Nino?
That the decline in cloud cover has caused some of the global warming according to CERES measurements has been noted recently, but the cause of the decline in cloud cover is as yet unclear as far as I know. It could be an amplification effect of the greenhouse effect, but has not yet been so predicted by climate models.
The TOTAL heat flow from the Earth to the surface works out to about .08 watts per square meter averaged across the globe. The total heat flow coming down from above is about 1380 watts per square meter.
This is a factor of about 17,000 to 1. Upwelling land heat is essentially rounding error in terms of what the Sun contributes and is highly unlikely to be a causal factor here.
Particularly since (AFAICT) there’s absolutely no reason to think that there is any increasing trend in the upward heat flux from said undersea volcanoes.
jgn,
Because the world catches sunlight on its cross-sectional area (π R^2) but has the total area of a sphere (4 π R^2), the incoming solar flux density is only 1361.5 / 4 = 340 W m^-2. Also, 29.4% of that is reflected away by the Earth’s clouds, ice, and a bit by the surface, so the flux density absorbed by the climate system is only 240 W m^-2. But your objection was correct in essence; the solar heating is overwhelming compared to the geothermal heating.
The “undersea volcanoes” hypothesis flounders on the radioisotope analysis of the new carbon dioxide, which clearly indicates that it’s coming from fossil fuels and not from volcanoes.
Also, there’s no reason to think undersea volcanoes are now suddenly increasing their output all over the world. This is a hypothesis of desperation by the deniers.
Hello Gavin, i go with Hansen that 1.4-1.5 will be reached very soon, as the EEI is now at extremely high levels and our SOx emissions are decreasing significantly.
Here is the latest Hansen post on the matter: https://mailchi.mp/caa/global-temperature-in-2022?e=176c11ab68
And what is very impressive and underlying the above is that we have now record levels of heat accumulation in the western Pacific Ocean (actually its out of the charts now), so the stage is set for an extreme El-NIno or more El-NIno’s the coming years: : https://www.pmel.noaa.gov/tao/wwv/gif/wwva_std_w.gif
Further we have record increases in methane levels (2022 will be similar or even higher than 2021), Arctic sea ice nearly vanished end of summer over its entire area, snow cover becoming also increasingly vulnerable, with marine heatwaves forming all over the place now.
My personal guess is that we reach a warming till 2030 with your above-used baseline of about 1.6-1.8 °C (Arctic sea ice in summer is the elephant in the room) in at least one year with no significant cooling afterward.
But most scary: after the next temperature jump things will get really ugly on our planet as we will be confronted with an even steeper non-linear increase in extreme events than what we observe after the last temperature jump in 2016 far exceeding what we thought possible (the first events we already have today)…
All the best
Jan
RE Gavin’s: “or a faster warming rate than the linear trend (which could relate to stronger forcings, or higher effective sensitivity). Any insight on this would be welcome!]
and Jan’s: “Hello Gavin, i go with Hansen that 1.4-1.5 will be reached very soon, as the EEI is now at extremely high levels”
For Gavin I would include “all of the above” and more (eg. biosphere “response”), including heat flux trend is not linear (the rate is increasing). For Jan, thanks for classifying current (approx. 1.2 Watt/m2) heat flux into the “Earth system” as extreme. However, with increasing Radiative Forcing (now exceeding 4W/m2), due to record annual emissions, that flux (which lags RF) is increasing at approx. 0.5 Watt/m2.
Mother Earth has an elevated temperature (due to some disease factor) and is going into critical.
My EEI heat flux “increasing at approx. 0.5 Watt/m2” is per decade (Hansen et al. submitted paper). I apologize for the omission. This is occurring over the entire surface of the planet, so multiply by that surface area (5.1 x 10 to the 14th power) for total present heating.
Hello Gavin. Is there a solid evidence-based explanation for the approx flatline over the period 1950-1975? I have been searching for some time but never found one.
In the context of major contributor (not claiming sole cause)
For a starter, review the aerosol pollution record and the direct & the indirect cooling radiative forcings
Of course, that pollution has come on varying degrees of control in regulatory jurisdictions over time
So after a rapid rise in the period noted, there has been a reduction in slope, then plateau, and in recent decade or so and decline
So masking and now reducing masking of warming from the positive GHG radiative forcing
Summary in IPCC AR6 WG1 Figure 2.10
William Owens
No, I would not call that ” a plateau” and decline after 2016. It is within the natural noise, the ENSO.
Look at the longer run. that is supposed to be the climate.
One can see better if one accepts and assumes those major causes and features, and that is what it is about.
If you are to secure and to serve data and hope that it will stand and be valid, you better look out for such things. regardless of dicipline.
I can use my own experience from other diciplines here and follow it, because I am aquainted to such things in empirical servography and oscilloscopy analogue signals which it is based on.
Also know a bit about free handed drawing having to represent something that ought to be reality.. And of optical illusions., & wishful thinkings..
Novum organum and idolæ mentis by Francis Bacon, for instance, on pensum first.
And perhaps Der Spieler, The Gambler, Dostojevski on wishful thinking and what it may come to cost.
MB: Hello Gavin. Is there a solid evidence-based explanation for the approx flatline over the period 1950-1975? I have been searching for some time but never found one.
BPL: Try here:
https://bartonlevenson.com/GreatStasis.html
People can look at. a graph and see different things. You see a “flatline over the period 1950-75.” Others may see an unusual surge in global temps during the period 1939-52. There were of course some rather significant developments during ’39-52, including major war and disruption in the global economy. A strong El Nino in ’41-42 may have been a factor as well.
This is readable Dr. Schmidt.
I wonder what I could read more closely out of Fig 1 with Nino and Nina and Neutral.
Jan
“My personal guess is that we reach a warming till 2030 with your above-used baseline of about 1.6-1.8 °C (Arctic sea ice in summer is the elephant in the room) in at least one year with no significant cooling afterward.’
Not quite sure what that means: “we WON’T reach a warming till 2030”?
Behind the paywall, there is a 2600 word article in Murdoch’s Weekend Australian of 14-15Jan23 by their in-house skeptical journalist Graeme Lloyd headlined “Weather ‘extremism’ fans fear in politics of climate”. The Murdoch papers are shunned by Australians concerned about climate change but with a large claimed national daily readership and an agenda to sow doubt about climate change their influence is concerning. In his latest effort Lloyd references concerns by “US climate scientist Judith Curry” that “psychological injury” is being caused to children by “apocalyptic” climate change rhetoric. As well as Curry, Lloyd quotes “fellow US climate scientist John Christy” and “Australian scientist Jennifer Marohasy” rehearsing their claims about the effect of urban heat islands and BOM methodology on surface temperature data analyses: the usual suspects making the usual claims.
On La Nina Lloyd makes the reasonable point that consecutive La Nina events are “relatively common”—half of all past Australian events since1900—but goes on to argue that three La Nina events in a row—four times since 1900 including the present one—are “less common”, implying three-in-a-row is also normal and natural.
Lloyd also writes: “The takeaway is that natural variability continues to play its role in climate against a background warming trend. According to BoM, the background heating from climate change has elevated average Australian temperatures by more than 1.47C since 1910. This compares with a global average increase reported by the Intergovernmental Panel on Climate Change of 1.07C since the industrial revolution.
I understand continental interiors warm faster than the global average. And also that the poles are warming faster. But perhaps when summarising this research for mainstream media consumption its worth pointing out that warming where many people live has already reached 1.5C. Because it’s not widely understood.
https://www.theaustralian.com.au/inquirer/explosion-of-extreme-weather-mentions-fans-fear-in-politics-of-climate/news-story/248494e7f41ba2d70512acafe4c31992 ($)
John Ransley, it’s interesting to see what the denial media/pundit industry always leaves out. So when Judith Curry acts concerned about The Kids these days – she never reflects on the distinct possibility that kids would feel a bit safer about the future if they didn’t see that a good many adults are actively promoting a do-nothing approach that will make climate impacts far worse than if the adults in charge were all working to address the problem together. No reason a “conservative” approach to actually fixing climate change wouldn’t have worked if it had ever been pushed by conservatives rather than the deny/delay/distract approach that became the preferred option.
And the same crowd acted the same for the pandemic – wailing and moaning about the harm done to The Kids from being held out of school – yet their preferred agenda of just rushing herd immunity by infection would have tended to make a lot more of those children lose parents, aunts, uncles, grandparents than actually did suffer that traumatic, permanent loss. But you would never find a comparison of the impact on a child from loss of adult family members vs loss of in-person schooling for a year or two.
It would be useful if schools started aggressively teaching critical thinking to students, and devoted a semester to critical examination of the kinds of “science” that gets promoted in Murdoch opinion columns.
You write: “For instance, the trends from 2016 to 2022 are -0.12±0.37ºC/dec but with such large uncertainties, the calculation is meaningless.”
Okay, but how large or small are the uncertainties in the data shown here in the graphs “GISTEMP anomalies (w.r.t. late 19th C) ….” and “Four surface-station based estimate of global warming since 1880” ?
Because the older measurements were made with glass thermometers and 3 readings per day, the uncertainties here should be greater than the measurements made in the last 40 years or so, which were made with electronic thermometers and data taken continuously in the minute and hour range.
[Response: The uncertainties in the annual means clearly increase as you go back farther in time, but the dominant uncertainty is spatial coverage, not instrument error or change. See here for more explanation. – gavin]
People weren’t quite as stupid in the olden days as you might imagine. Three readings a day does not mean they have to be lucky to catch the min/max temp.. Glass thermometers will still record min max. There are however a couple of issues with the change to electrical sensors
1) In locations that only took readings 2 or 3 times a day, there is a strong chance that the afternoon max may be missed or reduced
2) Glass thermometers have a natural high cut filter. Electrical ones do not. WMO guidelines say that electrical readings should be averaged over some minutes. This does not always happen, and never happens in Australia.. The hot part of the day is much more variable than the low and so the effect of using non-filtered readings is to increase the recorded temperatures compared with glass. On a typical hot day in Perth, this discrepancy can be greater than 1 degree
The largest source of uncertainty in the older data however is the huge area (70%) of extremely poor sampling pre-ARGO
Thanks, Gavin
But when the GISTEMP data have uncertainties from 0.05 °C for the last 50 years and then change to 0.15 °C until 1880, as NASA writes, why you write her in this Blog that there uncertainties of ±0.37ºC/dec ?
[Response: The first two numbers are the uncertainties in the estimate of a single annual mean number (in the last decade and in the late 19th C). The 0.37 is the uncertainty of the trend over the short and noisy period of the last 8 years. – gavin]
Gavin – “noisy period of the last 8 years”
This is based on what? newspaper headlines? Here is a plot of the Hadcrut4 standard deviation and variance on a lagging 8 year basis:-
https://photos.app.goo.gl/SjEDzWWPbgTzVjfb7
and for comparison, here is an ngram of “climeate extremes”
https://books.google.com/ngrams/graph?content=climate+extremes&year_start=1850&year_end=2019&corpus=en-2019&smoothing=0#
Gavin, sorry, but I didn’t understand why the uncertainty over an 8 year period is 0.37 and over a 50 year period is 0.1. Every data point has an uncertainty. If that uncertainty is 0.1 for each data point over the last 50 years, then it should be the same for the last 8 years.
James Hansen in his June 2021 blog shows a hiatus from 2016 to 2020/2021. And the data series from the various official measurements at woodfortrees/interactive show a slight decrease from 2016 to 2021, which is clear with the additional plot of the linear trend.
[Response: The uncertainty in a trend is given by the deviations from the line, not the uncertainty in the individual years. Basically, this goes up if the line is not a good fit – and given the interannual ups and downs, linear fits over short periods are very uncertain. Note to that the 0.05ºC uncertainty in a year is not even the same unit as the uncertainty in the trend (ºC/dec).- gavin]
The sun is the same temp every year. The earth is the same size every year. I suspect that if we could actually measure every cubic meter of the planet we would find the planet’s temperature steadily rising with little variation.
[Response: I don’t think so. ENSO and other chaotic elements of the climate system are the dominant cause of the interannual variability, not spatial sampling. – gavin]
I was thinking about temperature change and sampling.
it’s worth mentioning sea level rise.
while year to year variability is greater than rise, within 3 years that’s not the case.
For surface temperatures it’s closer to 18 years.
It might be wise to start posting both the average global land and ocean temperatures separately so that we can compare them with the overall global average. I think I’m correct in saying that the land average is close to 1.9C while the ocean average is close to 0.85C. Since most of use live on land, surely the land average is the one people should be thinking about?
[Response: We show that here, and you are roughly right, the last 5 years compared to the late 19th C, have land warming by 1.8ºC and ocean by 0.8ºC. But note the Paris Agreement limits are defined as the global mean, so they aren’t really comparable to the land-only numbers. – gavin]
@ c summerhayes
Really?
I never felt it that way, but I often felt that regional trends that are long enough to be reliable and clearly different from each other would be useful.
Such as Eurasia east and west of Ural, the eastern arctic and the western arctic that are clearly different, the southern and the northern Europe, eastern and western and southern north america and so on. Then the Australians will also believe us.
And this could also be given physical explainations so we can see and follow it for ourselves.
Also the main oceanic areas, “the seven seas” could be treated that way.
Climatic zones are allready well defined so it can be understood from anxient on. Regional predictions would follow up that well known tradition. Köppens climate categories in the old teachbooks of physical geography.
Yes Hr schmidt, 2 very fameous Köppens indicators wild oak and apple are coming over the hill right here, from southwest to northeast., so I can see for myself, The january isoterm on the map is clearly mooving to northeast here. IPCC has got a point.
And all that rain….. even in winter…. we can forget skiing and even skating….. and I had to secure the cellar- pumps that run and work more and more often..
For people to plan for the future, such rather regional aspects are important.
Make it practical and urgent practical for people where they live…..Then they will believe it and tell their children..
Besides ENSO, many researchers have also observed a correlation of global T variability to the AMO time-series, and this is just not the multi-decadal part of AMO. This brings up the question of whether some combination of AMO and ENSO would work better as a variability compensation since AMO and ENSO are not correlated with one another.
The most convenient way to observe the correlation is to use the online WoodForTrees graph plotter, choosing AMO and HADCRUT4 for example (with a bit of detrending of the latter)
https://www.woodfortrees.org/plot/esrl-amo/from:1920/mean:6/scale:0.8/to:2022/plot/hadcrut4gl/from:1920/offset:0.3/detrend:0.8/mean:6/to:2022
Is AMO a real oscillation? I say yes, as it is straightforward to model AMO via a Laplace’s Tidal Equations approach
MB: Hello Gavin. Is there a solid evidence-based explanation for the approx flatline over the period 1950-1975? I have been searching for some time but never found one.
BPL: Try here:
https://bartonlevenson.com/GreatStasis.html
V: We’ve been over this before, Bart. First of all, as you know, I’ve already demonstrated the weakness of the industrial aerosol explanation we see so often. If such aerosols had a significant cooling effect as claimed, then we’d expect to see evidence of underlying warming during the period in question in regions where industrial activity was absent or minimal. Only, as I’ve demonstrated with several specific examples, we don’t.
Moreover, if the additional factors you list were so important, then why would they suddenly de-activate during the period from the late 70’s through the late 90’s when temperatures shot up so dramatically?
Finally, the misleading nature of the scattergram you present in the link you provided ( https://bartonlevenson.com/CO218502019.html ) was made clear in a blog post I presented some time ago: http://amoleintheground.blogspot.com/2018/10/thoughts-on-climate-change-part-8-tale.html
As your scattergram is essentially the same as the one I analyzed in that post, the problem is the same as the one I revealed in that post, which I urge you once again to study.
Victor says: If such aerosols had a significant cooling effect as claimed, then we’d expect to see evidence of underlying warming during the period in question in regions where industrial activity was absent or minimal. Only, as I’ve demonstrated with several specific examples, we don’t.
The effect of aerosols on global temperatures was discussed in the past in great detail on this forum. References were made to peer reviewed studies that show that what Victor states here is an assumption made by someone not versed in the science. But of course, once again, Victor, the musicologist with no formal training in science, claims superior knowledge to those experts even after all this was explained in great detail. Typical Victor, rinse, lather, repeat.
I think you mean “blather, rinse, repeat.”
Oh please, not this idiotic nonsense from Victor YET AGAIN. If its not bore hole material by now, what is? Why doesn’t this website enforce its own rules? We all need a shakeup at times.
V: We’ve been over this before…
KDM: Indeed we have.
V: …I’ve already demonstrated the weakness of the industrial aerosol explanation we see so often. If such aerosols had a significant cooling effect as claimed, then we’d expect to see evidence of underlying warming during the period in question in regions where industrial activity was absent or minimal.
KDM: And we’ve pointed out to you that aerosols are not so precisely co-located as all that–tropospheric aerosols get ‘smeared’ over thousands of kilometers. See:
https://data.giss.nasa.gov/modelforce/trop.aer/
Still less is the net warming (or cooling) effect; circulation is after all mostly a hemispheric affair.
V: Moreover, if the additional factors you list were so important, then why would they suddenly de-activate during the period from the late 70’s through the late 90’s when temperatures shot up so dramatically?
KDM: Because from the 70s, the positive forcing from GHGs increasingly outpaced the negative forcing of sulphates. (Presumably this was partially due to the contemporaneous adoption of sulphate scrubbers, which inhibited the growth of aerosol emissions, but not those of GHGs. Aerosol emissions continued to grow more or less linearly, barring a couple of years in the 80s, but GHG emissions accelerated, in your word, “dramatically.”)
See:
https://data.giss.nasa.gov/modelforce/
Maybe you’d like to make a note of all this, so we don’t have to go over it yet again, some time in the indefinite future?
First I’d like to clear up the notion that I am simply a “musicologist” with no scientific training. Not true. On my high school graduation I was presented with the Bausch + Lomb award for excellence in science. In addition I earned perfect scores (100%) on all the NY State regents math exams, earning a full college scholarship as a result. As both an undergraduate and graduate student I studied perception psychology and linguistics, with extensive studies in anthropology, including training in basic statistical methods. In addition I’ve done a considerable amount of research in semiotics, culminating in a paper published in the flagship journal Semiotica. Additionally I’ve done a considerable amount of independent study in the philosophy of science, leading me to fully appreciate the importance of critical thinking, a skill that seems seriously lacking in these threads.. I have a long list of peer reviewed publications and have functioned from time to time myself as a peer reviewer.
In response to Kevin McKinney:
To refresh your memory, a presentation of 10 temperature graphs from 10 different remote regions can be found here: ( http://amoleintheground.blogspot.com/2021/03/thoughts-on-climate-change-part-10.html ) In every case we see no evidence of warming from ca. 1940 through the mid to late 70’s. This makes it impossible to argue that the expected warming trend had been negated during this period by the presence of industrial aerosols, since such a trend would have been evident in regions where little to no aerosol emissions had occurred. Unlike the wide distribution of CO2, aerosols quickly dissipate, as noted in the following paper:
“The distribution of anthropogenic aerosols’ climate effects depends on the geographic distribution of the aerosols themselves. Yet many scientific and policy discussions ignore the role of emission location when evaluating aerosols’ climate impacts. . . This suggests that climate accounting should differentiate between aerosols emitted from different countries and that aerosol emissions’ evolving geographic distribution will impact the global-scale magnitude and spatial distribution of climate change. . . Aerosols’ heterogeneous spatial distribution is recognized to influence their overall climate impact relative to more homogeneous climate forcers, like carbon dioxide.” (Divergent global-scale temperature effects from identical aerosols emitted in different regions, as published in Nature, August 2018)
KDM: . . . from the 70s, the positive forcing from GHGs increasingly outpaced the negative forcing of sulphates. (Presumably this was partially due to the contemporaneous adoption of sulphate scrubbers, which inhibited the growth of aerosol emissions, but not those of GHGs. Aerosol emissions continued to grow more or less linearly, barring a couple of years in the 80s, but GHG emissions accelerated, in your word, “dramatically.”)
V: That was a typo and if you look again at my blog post you’ll see that it was corrected. It was temperatures that accelerated dramatically, not CO2 levels, which rose at a more or less steady pace from ca. 1950 through the 21st century. It’s thus difficult to argue that the accelerating temperature rise during the last 20 years of the previous century was due to accelerating CO2 levels, as there was no such acceleration. As to the effect of sulphate scrubbers, no such scrubbers were mandated in China, yet we see essentially the same temperature upsurge in East Asia as elsewhere.
Victor,
“Unlike the wide distribution of CO2, aerosols quickly dissipate, as noted in the following paper…..”
I assume you understand that the wind can carry aerosols long distances and even if they are dispersed so they are at low concentrations they can still have some cooling effect. Single volcanic eruptions can cool wide areas of the planet. There could be other additional reasons for the flat temperatures mid last century including ocean cycles.
“It was temperatures that accelerated dramatically, not CO2 levels, which rose at a more or less steady pace from ca. 1950 through the 21st century.”
Although the graph of the Mauna Loa CO2 levels is roughly linear looking over time (it has a slight curve), actual concentration of CO2 in the atmosphere increased over time, (about 320 ppm in 1960 to about 420pppm now) and higher concentrations have a larger warming effect. Hence the acceleration of warming after about 1970 (coupled with the fact that aerosols were being reduced around that time). Victor still cant seem to understand all that and he clearly never will, or doesn’t want to. Because then his theory comes crashing down and that can be painful for the ego..
Yes, that and the fact that aerosols were emitted continually prior to the 70s. It used to be that the Sun in Los Angeles was yellow or red at noon!
What is there in “all that” do you insist I must learn to understand?
That “the wind can carry aerosols long distances and even if they are dispersed so they are at low concentrations they can still have some cooling effect”? Low concentrations have low effects, so what is your point?
“Single volcanic eruptions can cool wide areas of the planet”? True, but so what? Volcanic eruptions spew aerosols high up in the troposphere, which enables them to spread over a wide area, whereas industrial aerosols are emitted at ground level.
“There could be other additional reasons for the flat temperatures including ocean cycles. “? Yes of course. Ocean cycles are part of the natural variation that’s the most likely cause of the cooling trend.
” , , , actual concentration of CO2 in the atmosphere increased over time, (about 320 ppm in 1960 to about 420pppm now) and higher concentrations have a larger warming effect.”?
But the higher CO2 concentrations were largely due to increased industrial activity, which would have produced increased aerosol emissions. While efforts to reduce aerosol pollution were enacted in Europe and the USA, no such efforts were made in China or India, yet temperature increase in these regions was comparable to the worldwide increase during that period (late 70’s to late 90’s).
“Victor still cant seem to understand all that and he clearly never will, or doesn’t want to. Because then his theory comes crashing down and that can be painful for the ego..”
I have no theory, nigel. You’re the one promoting a theory, not me. What’s more I have no ego engagement in this issue whatsoever, which is why I never get all worked up over these discussions and see no need to make offensive remarks.
As you should be able to see, nigel (but will refuse to, obviously), there is no “all that” there, just a set of dubious assumptions with no evidence to back them up.
Reiterating again:
And have… and have…
As a hopefully interesting (and hopefully non-tendentious) comment, it interesting to note Fig. 2 in the Persad & Caldeira (2018) paper Victor cited, and which I discussed a little elsewhere.
https://www.nature.com/articles/s41467-018-05838-6
In 7 of the 8 cases considered, aerosol emissions–simulated ones, obviously–ended up causing a *warming* trend in some region in the opposite hemisphere. (Emissions from Western Europe were the exception, possibly because that is the most northerly region considered. Mute Arctic warming, and you mute global warming, too? India is at the opposite end of the spectrum; its aerosol emissions barely managed to nudge the globe in a cooling direction at all–just -0.02 C.)
The very inhomogenous trends and their global scale also offers some food for thought.
Victor,
“Low concentrations (of aerosols) have low effects, so what is your point?”
The point is even low concentrations of aerosols well away from their source could explain the flat temperatures last century in isolated locations around the planet, because it wouldn’t take many aerosols to mask the weak warming from low concentrations of CO2 mid last century.
And even if aerosols were not entirely responsible, aerosols are known to cause cooling from numerous lines of evidence, so must have had at least SOME effect even well away from their source. That much is simple logic. I suspect ocean cycles probably ADDED to the cooling effect of aerosols.
“But the higher CO2 concentrations were largely due to increased industrial activity, which would have produced increased aerosol emissions.”
No. Because by the 1970s industry was fitting sulphate aerosol scrubbers to remove aerosols.. Hence why warming became obvious after the 1970s along with the effect of higher CO2 concentrations.
“I have no theory, nigel.”
Your theory, or proposition if you prefer that word, is that aerosols are not to blame for cooling mid last century.
“and see no need to make offensive remarks.”
You are polite. So you get points for politeness, but no points from me for your pontifications on the science of this particular issue.
@ victor
Where did you have your holy victorious progressive inauguration and learnings- trainings of chosmology and systematic geopysics physical and political geography, & sphaerical geometry from?
Try and be honest now, looki back into yousrself and betray it to us.
That may help you a lot in your performance.
I might be able to help you then if you can tell that. .
What is there in “all that” do you insist I must learn to understand?
There has been significant discourse on aerosols on these RealClimate discussion threads in the past. But Victor either failed to read the responses and linked peer reviewed papers or completely failed to understand them. Typical behavior of Victor is to completely ignore the information and evidence presented and then after some time return to RealClimate and regurgitate his silliness.
So once again we are compelled to repeat the information. Unfortunately this is oh so tiresome and boorish. But that’s life with our dear Victor, a musicologist with no formal training in the physical sciences.
Anyway, in brief, the effect of aerosols on climate goes far beyond the direct radiative effects which Victor appears to be fixated on.
Aerosols have a huge effect on clouds. They promote their formation increasing cloud coverage, make clouds more reflective increasing the amount of sunlight reflected by the clouds, and increase cloud lifetimes. These effects all increase cooling and extend the regional effect of the aerosols.
Furthermore, the reflection of sunlight by aerosols and clouds have a significant effect on vertical temperature gradients and temperature gradients drive atmospheric circulation. Therefore, aerosols can and do effect the distribution of the reduced temperatures well beyond their areas of actual spacial coverage, even globally.
This is why general circulation models are used to show how aerosols effect global temperatures. And studies using these models clearly show that SO2 emissions from North America and Europe during the period of 1958-1980 likely had a significant global effect on temperatures.
In addition, one of the major lines of evidence that aerosols masked warming is that during the period of 1958-1980, night time temperatures continued to rise, which is exactly what would be expected with increasing greenhouse gas levels restricting heat loss to space. Natural variation nor ocean cycles can account for this nighttime warming. This is real evidence and not assumptive.
Some references:
Impact of global dimming and brightening on global warming
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2006GL028031
Local and remote mean and extreme temperature response to regional aerosol emissions reductions
https://acp.copernicus.org/articles/20/3009/2020/
Victor Grauer should consider just signing with his real name from now on. I asked ChatGPT something like what paper did Victor write in Semiotica https://www.degruyter.com/document/doi/10.1515/semi.1993.94.3-4.233/html
V: “…since such a trend would have been evident in regions where little to no aerosol emissions had occurred.”
Nope. That is merely reiterating what you had previously stated. Let me reiterate my first response:
(Others have made essentially the same points both on this thread and previously.)
V: That was a typo…
You misunderstand; I was saying in my own voice–other than your quoted word, “dramatically”–that GHG concentration forcing growth accelerated post-1970. Those wishing to corroborate that may do so at the following link, given in my previous comment as well.
https://data.giss.nasa.gov/modelforce/
The GHG forcings graphed for CMIP5, CMIP6, and also Hansen (2011) all show a marked acceleration between ~1970 & ~1990. (I’d embed images of these graphs here, if I could.) If you look at those graphs you’ll find that you are incorrect in asserting that “CO2 levels… rose at a more or less steady pace from ca. 1950 through the 21st century…”
V: “As to the effect of sulphate scrubbers, no such scrubbers were mandated in China, yet we see essentially the same temperature upsurge…”
Yet another reiteration of the same fallacy. You attempt to support your assertion by quoting a few words from Persad & Caldeira (2018), but you seem not to have absorbed the content of the paper as a whole very deeply. The first “result” reported is:
The second result:
Given the numerous other factors impacting regional temperature evolution, it’s no surprise that attempts to connect regional aerosol and temperature trends are not straightforward.
Instructive, in that regard, is a quarter of an hour spent playing with GISTEMP mapping, setting the time period for “the last 20 years of the previous century.”
The GISTEMP mapping tool link, for convenience:
https://data.giss.nasa.gov/gistemp/maps/
V: “…since such a trend would have been evident in regions where little to no aerosol emissions had occurred.”
Kevin: Nope. That is merely reiterating what you had previously stated. Let me reiterate my first response:
…aerosols are not so precisely co-located as all that–tropospheric aerosols get ‘smeared’ over thousands of kilometers. See:
https://data.giss.nasa.gov/modelforce/trop.aer/
V: Clearly that would depend on how high up in the troposphere the aerosols originated. Volcanic aerosols can spread widely, industrial aerosols, originating at or near ground level, do not. As should be obvious.
K: Still less is the net warming (or cooling) effect; circulation is after all mostly a hemispheric affair.
V: Irrelevant.
K: You attempt to support your assertion by quoting a few words from Persad & Caldeira (2018), but you seem not to have absorbed the content of the paper as a whole very deeply.
V: First of all, this is an extremely complex paper in which all sorts of factors are considered using a variety of different methods. Secondly it is based on more or less contemporary conditions — very different from those in effect during the period in question. Finally, regardless of what you think you may have found here or there in this paper, the conclusion, as stated at the outset of the “Discussion” section is unequivocal:
“These results demonstrate that geographic location substantially influences the cooling potential of a given aerosol emission. Crucially, countries that historically have or presently do account for the majority of anthropogenic aerosol emissions—Europe, the U.S., and China—are the regions whose emissions have the largest cooling potential.”
Weaktor,
Do me a favor and look up the logical fallacy of special pleading…
I didn’t need to look up “special pleading,” thank you Ray. I know very well what it entails.
When a rising temperature is expected according to one’s theory, yet no rising temperature is apparent, one then claims that the expected rise must have been masked by the emission of certain aerosols which just happen to be produced by the same process supposedly responsible for the expected (but nonexistent) temperature rise, THAT is special pleading.
When the evidence reveals no sign of the expected warming in regions where the presence of such aerosols was either minimal or non existent, yet one insists nonetheless that even trace quantities of aerosols would have the same cooling effect as in regions where the aerosols originated, THAT is special pleading.
When one insists that a long-term correlation between CO2 levels and global temperatures exists, despite the fact that the ONLY correlation apparent according to the evidence was limited to a single 20 year period, THAT is special pleading.
Ah, so it is clear that you aren’t even to the level of understanding logical fallacies yet–you fail at even basic logic. You posit that the theory posits that the temperature must rise monotonically. It does not. It says that all other things being equal–that is, ceteris paribus–the temperature will rise. But ceteris ain’t paribus. We know that aerosols can block sunlight–whether those aerosols are anthropogenic or volcanic in origin. We know solar irradiance fluctuates. We know the ENSO modulates cloud cover and this changes the planet’s albedo. We also know that there are other influences at play that influence the temperature year to year and month to month. However, Tamino showed quite convincingly that if you correct the temperature record for the influence of the first three factors above, you get much closer to a monotonic rise.
So, the entire premise of your statement–indeed of your entire output here at RC–is false, so your conclusion is irrelevant. BASIC LOGIC!!!
Special pleading is probably an understatement.
V: When one insists that a long-term correlation between CO2 levels and global temperatures exists, despite the fact that the ONLY correlation apparent according to the evidence was limited to a single 20 year period, THAT is special pleading.
J: When one has to reject the long-established mathematical definition of correlation in order to insist that a particular 20 year period chosen ex post facto represents the only “apparent” correlation in a long-running time series exhibiting very strong (above 0.8) correlation, and do it despite repeated corrections… I leave it to the reader to decide whether this is special pleading, errant and obdurate misuse of a simple statistical technique in the service of one’s hypothesis, or deliberate and serial promotion of a blatant falsehood.
For the most recent detailed discussion of this issue, I refer anyone unfamiliar with it, and lots of time on their hands to the Dec. 2021 archives, especially the latter postings.
And what does “cooling potential” mean in Persad et al? You don’t explain it, Victor, but Persad et al do. And it doesn’t have a whole lot to do with your contention.
(I’d suggest anyone in doubt read the paper as linked above, because Victor is selling a pig in a poke here.)
Victor states his life experience is such that it is “including training in basic statistical methods.”!!!
Since he has clearly on scores if not hundreds of occasions has shown he has not one single clue what a correlation even is in any formal geometric or algebraic sense, I question the value of his life experience. He may have been given relevant experiences but he clearly has not benefited from them.
Weaktor says he had “training in basic statistical methods.”
Blink, blink, blink.
Hmm, guess it didn’t take.
Statistics won’t do you much good, Ray, if you can’t add 2 + 2.
Hr. V. Grauer,
You must also know how to draw the square root of the summa summarum and to suggest that first, …. else you learnt no statistics. and betray that you are just a bluff from the side of the Progressive Party with P..
So you are saying your innumeracy extends to basic arithmetic, and that is why you are a statistical idiot?
“If.”
nigelj says
Victor,
“Low concentrations (of aerosols) have low effects, so what is your point?”
The point is even low concentrations of aerosols well away from their source could explain the flat temperatures last century in isolated locations around the planet, because it wouldn’t take many aerosols to mask the weak warming from low concentrations of CO2 mid last century.
And even if aerosols were not entirely responsible, aerosols are known to cause cooling from numerous lines of evidence, so must have had at least SOME effect even well away from their source. That much is simple logic. I suspect ocean cycles probably ADDED to the cooling effect of aerosols.
V: These are assumptions, nigel, based on wishful thinking. Whereas I’ve provided evidence. According to the EVIDENCE, there is NO sign of an underlying warming trend during the period in question in regions where little to no industrial activity took place. If you want to argue otherwise you need to provide us with evidence. Science is based on evidence, not assumptions.
“But the higher CO2 concentrations were largely due to increased industrial activity, which would have produced increased aerosol emissions.”
nigel;: No. Because by the 1970s industry was fitting sulphate aerosol scrubbers to remove aerosols.. Hence why warming became obvious after the 1970s along with the effect of higher CO2 concentrations.
V: According to the EVIDENCE, no such scrubbers were employed in China or India, or indeed anywhere else except the USA and Europe. Thus, in most parts of the world, aerosol production would have risen along with the rise in industrial activity that produced CO2 emissions. Yet, according to the EVIDENCE, the rise in aerosols in these regions failed to produce any discernable cooling effect. Temperatures rose in these regions at roughly the same rate as it did worldwide.
“I have no theory, nigel.”
nigel: Your theory, or proposition if you prefer that word, is that aerosols are not to blame for cooling mid last century.
V: The notion that “aerosols are not to blame for cooling mid last century” is YOUR theory. Based on assumptions, NOT evidence. I have no theory to explain what happened during that period, but I do see the glaring weaknesses in yours. The critical assessment of a theory is not a theory, but simply a critique.
Correction. Nigel’s theory is that aerosols ARE to blame for the cooling. Sorry for the mix-up.
Victor.
The ‘evidence’ you quoted comprises some locations mid last century that were isolated from aerosol sources but still had flat temperatures. However you haven’t convinced us that aerosols cant spread widely and have a cooling effect on those locations. The paper you quoted does not say aerosols dont spread widely form their source. It only says some aerosols don’t ( originating in India for example).
Aerosols spread widely because of the way the global circulatory system and winds work. And read the comment up the page by CCHolley which has specific research on how aerosols behave.. Plenty of evidence there. You haven’t shown any errors in the material he quotes.
You are well educated, but you persist with some strange ideas about things. There are elements of anthropogenic warming theory that deserve some healthy scepticism, but you are missing those, and focusing on things like the explanations for flat temperatures, and correlations of warming and CO2 last century, that are not contentious or suspicious looking to me. Even the hard core degree qualified denialists dont make a big issue about those things, because explanations are obvious and sufficient, and simple maths tests show a good correlation. For gods sake investigate some other issue and move on.
Victor has suggested up the page (paraphrasing) that aerosols can’t explain the flat period of temperatures mid last century on the basis that some locations far distant from any aerosol source still show flat temperatures, and that aerosols would stay close to their source, so something else must be responsible for the flat temperatures. He used the following paper to argue this:
Divergent global-scale temperature effects from identical aerosols emitted in different regions
https://www.nature.com/articles/s41467-018-05838-6
And he referred particularly to this quote back up the page: “Aerosols’ heterogeneous spatial distribution is recognized to influence their overall climate impact relative to more homogeneous climate forcers, like carbon dioxide”
However he failed to mention this quote from the study “In other words, regions like Western Europe, Indonesia, and (to a slightly lesser extent) the United States strongly export the climate impacts of their (aerosol)emissions, while regions like India more strongly experience the cooling effects of their own (aerosol) emissions.” (The coloured maps show this quite well).
This suggests to me that Victor may have missed reading a part of the study, and that aerosols do frequently spread quite widely from their source on air currents, and still have cooling effects on locations that are distant from the source.
As a newcomer — and Without taking a side in this argument — does anyone have any estimates for the uncertainty in the cited aerosol models? E.g, how spatially dense was the collected data that was input to the models, what was the uncertainty in the measurements, effects of interpolation and resulting uncertainty in the computed temperature effects.
PS I had checked “START HERE” for info on this subject. This 2007 article from New Scientist seemed the most relevant:
Climate myths: The cooling after 1940 shows CO2 does not cause warming | New Scientist
However, Fig SPM-2 of the article shows Radiative Forcing from CO2 to be 1.66 (1.49 to 1.83) W/m3. However, the Total Direct Effect for Aerosol ranged from -0.9 to -0.1 and for Cloud Albedo Effect it ranges from -1.8 to -0.3. That is a lot of uncertainty –from Major influence to No Influence
If there is a latter peer-reviewed article in a reputable journal that settles the matter, then perhaps it could be added to the START HERE list for citation.
PPS Quote from the 2007 New Scientist article:
“Then there is the question of how all the different aerosols affect clouds. Climate scientists acknowledge that the aerosol issue is one of the key uncertainties in their understanding.”
@Gavin says: – ” What influence does ENSO really have?
It’s well known (among readers here, I assume), that ENSO influences the interannual variability of the climate system and the annual mean temperatures. El Niño events enhance global warming (as in 1998, 2010, 2016 etc.) and La Niña events (2011, 2018, 2021, 2022 etc.) impart a slight cooling. ”
ms: — Sorry Gavin – it’s the other way around. El Nino years mitigate the increase in global warming & EEI and are therefore far more beneficial to humanity and the galloping warming Earth climate in the long term.
https://pub.mdpi-res.com/atmosphere/atmosphere-12-01297/article_deploy/html/images/atmosphere-12-01297-g004.png?1634310863
La Nina years can be ~0.5°C cooler than El Nino years because they channel large amounts of energy into the ocean depths in the western Pacific, El Nino years are characterized by the better release of the stored energy in the Pacific Energy through the higher SST, LW-up-surface, evaporation & cloud albedo.
Since the Pacific, at 165 million km², is larger than all land areas combined, an El Nino usually transports significantly more water vapor (~3400km³) into the atmosphere than a La Nina.
So your sentence is only correct if you replace “global warming” with “temperature increase on the surface” – because it’s not the same.
It is widely unknown (among readers here I assume) that an El Nino year (eg. 1998, 2010, 2016) ALWAYS increases relative & absolute humidity (~ +0.5% and ~ +0.2g/Kg respectively).
https://climate.metoffice.cloud/humidity.html
However, according to the common opinion of the climate community present here, this increases the GHE –
…and the knowledge that global warming is slowed down with higher GHE through water vapor is probably suitable for the climate experts present here … to finally fall into a crisis of a deep climate coma.
Most people here will probably not wake up from this coma – before they realize that the earth is a water-cooled planet and that the real climate (lol) above all needs a lot of water and evaporation on the (land) surface to fight & slow down global warming.
However, these findings also fundamentally relativize the importance of the individual climate gases H2O, CO2, CH4,… the doubling of the CO2 concentrations, for example, has a much smaller influence on the earth’s climate than many “climate experts” here assume.
The temperature differences between El Nino & La Nina of ~ 0.5°C can also be observed in the atmosphere between the troposphere and stratosphere.
https://www.metoffice.gov.uk/hadobs/hadat/images/update_images/global_upper_air.png
The graph shows that many climate scientists confuse the loss of evaporation with higher GHG concentrations.
They argue that a cooling lower stratosphere and rising temperatures in the lower troposphere are caused by higher concentrations of CO2 — far from it… — it’s the globally falling relative humidity, desertification and the loss of evaporative landscapes that is to blame.
Have you ever heard of Phase- shift, genosse Schürle?
You, the flat earthers and desert walkers, seem also to ignore 70.8 of the earth global surfrace with fierche and white evaporative interaction between air and water. Subtract antarktis and Grønland and it will be even much more.
And that the dry, desert winds from your locations are drying up the oceans nextby,….. that are really huge however, …. and getting warmer and warmer.
When all the waters are flying in the air due to fierce winds the roaring fourties and the fierceful fifties,…, how can it then be about “evapo- transpiration” more or less when temperature and clausius clappeyron rules that all ?
The weather maps and models on the net now show even white snow in southern California and even south of that,… and 3-4 meters of packed snow uphill,….. so how can it be about “evapottranspiration” in Silicon Valley, Hollywood and in Las Vegas and in Central valley?
When one can go skiing from Dallas in Thexas all the way to Basel and even to Paris,…what about that?
Just because the Orcs and the Puttlers cannot so easily drive Troika anymore.
Free inquiry is frowned upon in climate science, as there appears to be a sort of unspoken terms of reference, or charter, under which the entire discipline operates. This imposes certain high-level requirements, assumptions, constraints, and descriptions. Any deviation from the charter will be met with hostility. The charter dictates that the goal is the elimination of excess greenhouse gas emission. While we can all agree this is a sensible goal, the unintended consequence is that it inhibits and constricts discovery of the nature of the Earth system, including the human interactions. Therefore, the lifeblood of of the scientific endeavor is eroded, having been reduced to a set of narrow beliefs and simplifying assumptions.
nigelj: However [Victor] failed to mention this quote from the study “In other words, regions like Western Europe, Indonesia, and (to a slightly lesser extent) the United States strongly export the climate impacts of their (aerosol)emissions, while regions like India more strongly experience the cooling effects of their own (aerosol) emissions.” (The coloured maps show this quite well).
I don’t accept for a minute that aerosol pollution originating in highly industrialized areas would have been strong enough to mask the expected warming that failed to materialize in regions with little or no industrial development during the period ca. 1940-1979. While the paper in question refers to “strongly exported . . . climate impacts” from highly industrialized areas, the notion that such impacts would be comparable to the cooling effects we see in such source areas strikes me as absurd. As should be clear, the initial sentence of the abstract says it all: “The distribution of anthropogenic aerosols’ climate effects depends on the geographic distribution of the aerosols themselves.” Contrary to nigel’s assumption, this does not mean that the dissemination of aerosols in certain remote regions could possibly produce cooling effects comparable to those recorded in the regions where such aerosols originated.
In order to go into greater depth in researching this issue I decided to examine the temperature records of some of the least polluted places in the world. And since I managed to find a website that identified seven such places that’s where I decided to look. The website is titled “The 7 cities with the cleanest air in the world.” ( https://airly.org/en/the-7-cities-with-the-cleanest-air-in-the-world-ranking/ )
The list begins with the cleanest city, Zurich. Here’s a graph representing its climate history since, roughly, 1955: http://berkeleyearth.lbl.gov/auto/Stations/TAVG/Figures/23561-TAVG-Raw.png
From that year to 1980 we see NO warming trend.
Next on the list is Reykjavík. Here’s a graph of Icelandic temperature history, including Reykjavík among some other cities, represented by the green line: http://www.euanmearns.com/wp-content/uploads/2015/02/iceland_temperatures_8.png
Throughout Iceland, including Reykjavik, we see a clear downward trend from ca. 1930 through 1980.
Next up: Launceston, Australia. Here’s the graph: http://berkeleyearth.lbl.gov/auto/Stations/TAVG/Figures/151767-TAVG-Raw.png
No warming trend from 1940-1980 (and beyond).
Continuing down the list: Honolulu: http://berkeleyearth.lbl.gov/auto/Stations/TAVG/Figures/169973-TAVG-Raw.png
We see a steep dip from 1940-1950 followed by a rise that levels off from roughly 1960 to 1980. At no point does the temperature rise above or even close to the 1940 level.
Next: Bergen. http://berkeleyearth.lbl.gov/auto/Stations/TAVG/Figures/157188-TAVG-Raw.pdf
No significant trend until the late 1990’s.
Next is Wollongong, Australia — unfortunately I was unable to find a graph for that city.
Finally: Trondheim, Norway. http://berkeleyearth.lbl.gov/auto/Stations/TAVG/Figures/19012-TAVG-Raw.png
From ca. 1840 through ca. 1980 there’s a slight downward trend.
In none of the discussions describing conditions in any of these places is there any mention of pollution originating anywhere other than local sources.
Correction: the downward trend in the Trondheim graph begins in 1940, NOT 1840.