I like that graph, johnmath: "Annual Anomalies, 1850...". Free of clutter and clearly labelled.
I am a bit surprised that there is practically no lag of sea surface temperature (or night marine air temperature) behind land surface air temperature.
As always, I still want to see the explanation of why the temperature rose almost as fast from 1910 to 1940 as it did after 1975, and why it failed to rise at all from 1940 to 1975.
Todays science show on ABC.
Lisa-ann Gershwin, Marine and Atmospheric Research CSIRO predicts in this talk we are close to extinction and it's probably too late to do anything about it.
dbindoff
Member
All very gloomy outlooks. Thought I might as well throw in a roundup of the permafrost issue.. http://theconversation.com/methane-and-the-risk-of-runaway-global-warming-16275
johnmath
Member
Catopsilia said:
As always, I still want to see the explanation of why the temperature rose almost as fast from 1910 to 1940 as it did after 1975, and why it failed to rise at all from 1940 to 1975.
Before 1940, the increase in temperature is believed to have been caused in the main by increased solar activity and low volcanic activity.
The mid-century cooling was primarily caused by a rapid increase in atmospheric pollution from the burning of fossil fuels, causing global dimming.
The main reason for the sudden movement in global temperature from the '70s was the passage of Clean Air Acts around the world in response to air pollution and acid rain, thus removing the dimming effect of pollution.
Thanks for the reply, johnmath.
Where is this explanation documented? Is it well supported?
johnmath
Member
Catopsilia said:
Thanks for the reply, johnmath.
Where is this explanation documented? Is it well supported?
Well, I think hundreds, perhaps thousands, of climatologists and scientists in related fields have worked on this. The IPCC has reviewed thousands of scientific papers and theories and its findings on 20th century temperature changes can be found here: http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-4.html
Basically, the IPCC concludes that there isn't any other plausible explanation that fits the observations. You'll have to do a LOT of reading of references to see how thorough the studies have been and how this conclusion is drawn. Any "sceptical" theory that has been proposed has been tested too because, as we all should appreciate, scepticism is THE key driver of scientific discovery.
Johnmath
To illustrate why I am bothered by the decline in global temperature between 1940 and 1975, I offer these graphs:
The cooling in the 1940-1975 period would call for explanation even if the carbon emissions had been steadily increasing before, during and afterwards. This was not the case. The period from 1945 to 1973 was the time of the most rapid increase in emissions (+2.14 log-cycles per century). The second most rapid increase in emissions was from 1850 to 1913. This earlier period included the other documented period of global temperature decline: from 1879 to 1909.
The two acknowledged periods of rapid global temperature rise, 1909-1943 and 1975-2005, were times when the growth of global emissions was slower than average for the 163-year record.
The originals of these graphs were posted, with discussion, in a weatherzone forum "Climate and Climate Change"
http://forum.weatherzone.com.au/ubbthreads.php/topics/1191136/Re_Inter_decadal_climate_cycle#Post1191136
This forum has now been closed, as stated here:
http://forum.weatherzone.com.au/ubbthreads.php/topics/1201332/Closure_of_Climate_Change_foru#Post1201332
Note: " There will be NO discussion of any climate change-related topics in any other forum."
At least part of the "childish behaviour" mentioned by the moderator was deliberately provoked by a troll determined to close down discussion of climate change. The troll boasted of the success of the tactic in another website, mentioning that being very polite was a part of the method.
This is the first time that my freedom of expression has been curtailed by a troll. It hurts.
johnmath
Member
Catopsilia, global air temperature is only a proxy for global warming. 90% or so of the heat trapped on the Earth goes into the oceans in the first instance, and the heat transfer into the air depends on the complex interplay between ocean currents and weather systems, amongst other things.
Nothing in the record of the air temperature challenges the reality of the change in the energy balance (the difference between inward and outward radiation) which is the reason for global warming, and this can, has been and is being measured directly. So if the air temperature isn't playing nicely and following the CO2 in the atmosphere directly, you can blame it on the weather. The fact changes nothing about the physics of global warming and the seriousness of the impending calamity.
In relation to the other forum which was closed due to "childish behaviour shown by members on both "sides" of the discussion" my I remind you that nature doesn't have "sides". Global warming isn't going to stop because the "sceptical side" wins an argument. It's in the records, but you have to look at the WHOLE picture, not cherry pick one data set that "proves" what is just a logical fallacy.
Benny
Member
Catopsilia, I think looking for a direct, uniform, consistent link between CO2 levels/emission rates and temperature rises is the problem. When climate scientists say that CO2 is causing the increase in temperature it doesn't mean that all other effects have disappeared. All climate scientists would acknowledge that there are other effects that especially in the short term can over-ride the consistent positive effect of increasing CO2. A big volcano can in one year decrease the global temp by much more than the continuous effect of CO2 as can El Nino etc. Thats why they often mark up charts showing the yearly or 10 yearly global temp with specific volcanic and El Nino/La nina events and the (temporary) effect is clearly seen.
Just because CO2 levels/emission rates are not continuously positively correlated with temperatures doesn't mean its not the cause - thats why we have complicated models that need to take in to account all factors.
BTW - doesn't that chart show a very bad case of cherry picking the points of linear fit to the temp record. I can see why someone might want to draw straight lines matching that staircase type chart, but unless there is a reason for picking those dates how can it be valid. To just pick the successive absolute max and min and draw lines to exaggerate the steps doesn't seem valid to me. Fit a line through the whole chart and what does it look like - is the most confident prediction of what is happening to temperature ?
johnmath
Member
Thanks Benny. Global warming is of course the warming of the close-to-ground (“near surface”) air AND upper ocean water temperatures. If you have a look at the ocean water AND air temperatures the decline in temperature from 1945 to 1970 mysteriously disappears! It is actually flat, which is still not a rise, however if you have a look at radiative forcings across this period, the heat input was down, so actually the temperature should have been going down. The fact that it wasn't going down is proof of a rising positive energy balance, which is of course correlates with the level of CO2 going up.
http://www.changecollege.org.uk/img/GISS_EMIC_1945_1970.jpg
http://www.joabbess.com/2012/04/13/whats-up-answer-everything-3/#more-13384
Benny
I must answer your assertion that my graph is in some way "cherry picking" and not "valid".
Surely, you cannot deny that the global temperature trace is almost linear from 1909 to 1943, and again from 1975 to 2005. If you do deny it, please say so.
If you will grant that, then the reality of inflection points at 1909, 1943 and 1975 are, to my mind, also undeniable. It is not as if I wished to find that inflections occurred at any particular dates. That would be cherry picking.
(I have mentioned elsewhere that an inflection point at 2005 is not yet well supported by evidence.)
If 1943 and 1975 (for example) are accepted as valid inflection points, then what is the simplest expression of the temperature trend between them? I suggest it is a straight line. You yourself argue that fitting a straight line is valid for prediction, but you prefer to fit it "through the whole chart".
I assert that the form of both the temperature and the emissions traces fit very well to a series of linear (or log-linear) trends, and that no cherry picking is involved.
I know very well that many other factors affect the global temperature, but the fact that it did not increase from 1943 to 1975 has not yet been explained by some factor known to have operated persistently for those 32 years and not to have operated before or afterwards.
johnmath
Member
Catopsilia said:
Surely, you cannot deny that the global temperature trace is almost linear from 1909 to 1943, and again from 1975 to 2005.
It's easy to deny because your graph does not support that assertion. Global air temperature is NOT global surface temperature.
many other factors affect the global temperature, but the fact that it did not increase from 1943 to 1975 has not yet been explained by some factor known to have operated persistently for those 32 years and not to have operated before or afterwards
Please provide a critical analysis of the references in my previous post that did exactly what you claim hasn't been done...
dbindoff
Thanks for the reference to the 2013 paper by Hansen, Karecho and Sato.
On their Figure 1., "Global Fossil Fuel CO2 Annual Emissions" the black curve (Total) is the same curve as on my graph, but I have converted it to Log10 values. This is proper: the basic model relating global temperature to emissions is that temperature increases with the log of the emissions. ("fast-feedback climate sensitivity is ~3 °C for doubled CO2").
Because of this scale conversion, the sharp rise in CO2 emission rates after 2000 is not so pronounced on my graph, and is almost obscured by my "2005" label. My graph makes abundantly clear what is hard to detect on the other graph: the near-constant proportional rate of increase in emissions from 1945 (or 1950) to 1973 was more than twice as high as that from 1973 onwards. This is precisely the opposite of what the basic model predicts.
A lot of the discussion in the paper you reference is about variability from year to year. You will remember that I posted graphs about this many pages earlier in this thread e.g:
http://www.ata.org.au/forums/topic/2190/page/14#post-24127
Hansen, Karecho and Sato write mainly about the last 30 years, because many things simply were not observed earlier.
I believe you are right to mention in particular the factor: negative forcing due to human-generated aerosols. I think that may well be the key to understanding the rather strange relation between increasing CO2 emissions and global temperature rise shown on my graph. (To be fair, johnmath mentioned this, which I will answer below.)
The concept is "global dimming".
Hansen and a co-worker had earlier described the opposing effects of (a) blocking of sunshine by aerosols produced by burning fuels (especially coal) and (b) trapping of sunshine by emission of carbon dioxide as a "Faustian Bargain" - a deal with Satan.
http://pubs.giss.nasa.gov/docs/1990/1990_Hansen_Lacis.pdf
Burning dirty fuels, such as coal, and polluting the sky with aerosols, reduces the rate of warming for the time being only. It does not affect the rate of accumulation of CO2, so it merely postpones an inevitable warming.
I infer that the reason scientists such as Dr Hansen have not put forward a model based on aerosols that accounts for the 33-year period without global warming is simply a lack of data on aerosols. There is very little data now, let alone in 1950.
"The difficulty is human-made aerosols. Aerosols are readily detected in satellite observations, but determination of their climate forcing requires accurate knowledge of changes in aerosol amount, size distribution, absorption and vertical distribution on a global basis—as well as simultaneous data on changes in cloud properties to allow inference of the indirect aerosol forcing via induced cloud changes. Unfortunately, the first satellite mission capable of measuring the needed aerosol characteristics (Aerosol Polarimetry Sensor on the Glory satellite, (Mishchenko et al 2007)) suffered a launch failure and as yet there are no concrete plans for a replacement mission."
(Note: This is the paper that contains the famous statement: "What is clear is that most of the remaining fossil fuels must be left in the ground if we are to avoid dangerous human-made interference with climate.")
johnmath
On 27th July you said:
"The mid-century cooling was primarily caused by a rapid increase in atmospheric pollution from the burning of fossil fuels, causing global dimming.
The main reason for the sudden movement in global temperature from the '70s was the passage of Clean Air Acts around the world in response to air pollution and acid rain, thus removing the dimming effect of pollution."
When I asked:
"Where is this explanation documented? Is it well supported?"
You replied in generalities.
I have since found that same explanation here:
http://www.skepticalscience.com/The-main-culprit-in-mid-century-cooling.html
That is not a website that I trust, so I remain unconvinced.
Clearly James Hansen does not endorse this explanation, or he would have mentioned it.
A quick response, johnmath.
I don't see a critical difference between the global temperature data I used and the one that your source used.
I used HadCRUT4.1.1.0 annual N-S average smoothed.
Website:
http://www.metoffice.gov.uk/hadobs/hadcrut4/data/current/download.html
File:
file:///C:/Users/win7/Downloads/HadCRUT.4.1.1.0.annual_ns_avg_realisations.zip
Your source said she was waiting on new HadCRUT4 data, so used GISS instead.
When I read the page you referenced, the only relevant point I found was:
"The “doldrums” in global warming in the period between 1945 and 1970 is easily explained,..." with a link on "easily explained".
The link was to the website I mentioned at the end of my previous post.
johnmath
Member
Catopsilia said:
When I read the page you referenced, the only relevant point I found was:
"The “doldrums” in global warming in the period between 1945 and 1970 is easily explained,..." with a link on "easily explained".
Are you sure? Here is the link again:
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch9s9-4.html
Hi johnmath
I referred to the link(s) in your post of 8:02 on 29 July. I see you meant the link you posted at 9:16 on 28 July, which is part of the IPCC 4th assessment report.
I don't think there is anything there that I wish to dispute.
Benny
Member
Catopsilia - when I say the points are cherry picked, I mean that other than observing that there appears to be a turning point ( I think you'll find an inflection point is something else) what reasons are there for picking those particular dates ? Why 1975 and not 1974 or 1976 ? In particular why 1879 and not 1875 ? The particular points picked seem to be the successive min and maxima - which will exaggerate the positive and negative slopes - which is what I said. If you were looking for a piecewise linear model wouldn't you allow iterative selection of the end points to get the overall best fit ?
It does appear to be almost linear from 1975 to 2005 - but I still don't think this means there is a linear model prevalent during this time. The year to year variability is so high that I think its just a coincidence that all the various factors affecting climate during this time happened to make it appear (almost) linear.
I did not argue that fitting a straight line is valid for prediction - but if you are going to fit a straight line to get some idea of a general trend, then wouldn't you fit it to the biggest set of data to get the best idea ?
You are obviously more widely read on this than me - I do not have time to chase up and read detailed source papers, so I will tend to believe the majority of climate scientists and act on their advice/opinion.
Benny - the precise location on my graph of turning points where trend lines change or cross (that I called inflection points) is not critical.
These changes in approximately linear trends are very large indeed: they are not much different from the over-all rates. Typically, my successive estimated linear trend lines differ by about +/-2 degrees per century, which is much the same size as the over-all estimate of temperature increase. For CO2 emissions, each change between successive estimated linear trend lines is more than one log-cycle per century, when the over-all rate of increase is about 1.6 log-cycles per century.
Choosing different turning point dates (or different data values) would change the estimated trend line slopes only slightly.
In fact, I do not see much latitude for choosing alternative dates for turning points, except (I agree) in the case of 1879. There are more mathematical methods of identifying turning points between trends, and I have used them, but they are hardly necessary in this case.
The temperature data values I used are strongly smoothed. The HadCRUT authors chose to apply a 21-point binomial smoothing function to annual values, wiping out all cycles (such as ENSO) shorter than a decade. This suited my purpose. The invalid "cherry picking" of graphical data that has been criticised on the web has typically occurred where the original data had not been smoothed, allowing wildly different turning points to be selected from within the noise.
johnmath
Member
Catopsilia said:
Hi johnmath
I referred to the link(s) in your post of 8:02 on 29 July. I see you meant the link you posted at 9:16 on 28 July, which is part of the IPCC 4th assessment report.
I don't think there is anything there that I wish to dispute.
Catopsilia, the IPCC AR4 is an attempt at a review of ALL of the science on the subject. The section I linked deals with how the air temperature record of the 20th century can be reconciled with data like CO2 levels. The skepticalscience.com website, which you seem to dislike, is (mostly) a layman's interpretation of the same research with the same conclusions (funny about that!) So you can find your answer at whatever level of complexity you want, but the answer is still pretty much the same.
Many thanks for that reference, Benny. That is exactly the research result that I felt was still missing. It WAS missing - the date of publication was just two months ago.
In case anyone else wants to read the paper, that link fails for me as the pdf file is too big. I was able to access the paper here:
http://m.iopscience.iop.org/1748-9326/8/2/024033/article
The paper is:
L J Wilcox, E J Highwood and N J Dunstone (2013) "The influence of anthropogenic aerosol on multi-decadal variations of historical global climate." Environmental Research Letters 8 024033
According to the paper, it is not the direct effect of aerosols on solar radiation but the indirect effect of aerosol-cloud interactions which allows the climate models (finally) to match the observed cooling of the 1950's and 1960's.
Greg C
Member
While we argue the minute the problems go on. A plea for action from the Marshall Islands. The longer we wait to do something, the more expensive it will be. But that has been said many years ago, therefore we must be in the expensive to fix zone already
http://www.abc.net.au/news/2013-07-30/de-brum-climate-change-marshall-islands/4852760
2013 shaping up to be one of Australia’s hottest years on record. Certainly the 'warmest' winter I've seen here in CQ since I moved here in 1987.
"A feature of the last 10 months has been the persistence of unusually warm temperatures. Every calendar month since September 2012 has had temperatures 0.5°C or more above normal. The result has been a national mean temperature anomaly of +1.03°C for the past 10 months, well ahead of the previous record of +0.94 °C set in 1997-98."
https://theconversation.com/2013-shaping-up-to-be-one-of-australias-hottest-years-on-record-16295
TonyT
Member
continuing from
http://www.ata.org.au/forums/topic/2190/page/30#post-40218
the Mechanism for Global Warming is described at
http://en.wikipedia.org/wiki/Greenhouse_effect
.
where the Charts include:
.
.
and
.
Note that in the second Chart the X-axis increases from Right to Left.
Rockhampton Bureau of Meteorology observer Brendan Bradford said the 1943 record of 37.1 degrees was overtaken at 3.17pm yesterday.
While it was a hot day for Rockhampton residents, Biloela and Emerald also had record days, reaching 38 and 39.9 respectively.
Each of those readings was more than three degrees over their highest on record.
Latest IPCC press release. It ain't pretty.
https://www.ipcc.ch/news_and_events/docs/ar5/press_release_ar5_wgi_en.pdf
After our hottest winter and September on record here is what is really going to happen.
Plan for weather or plan for war.
The new Climate Council has issued a report on the September heatwave.
http://www.climatecouncil.org.au/wp-content/uploads/2013/10/cc.offthecharts1.pdf
