Really Sciency

Visit my other blog 'Really Sciency' looking at Climate Science and its portrayal, misrepresentation and denial in the media.

Friday, 2 September 2011

What observations would be inconsistent with AGW theory?

It can be fascinating to see how AGW skeptics and out right deniers deal with the supporting science.  Some just go quiet while others try to form logical arguments to allow them to reject it and confirm their own bias. This recently happened to me.
On Paul Hudson’s blog a climate skeptic asked;

"Can you tell us what observations would be inconsistent with AGW theory?"

Remembering the question was what observations would disprove AGW, I thought of a list of 5 things;

  1. No increase in ocean acidification.
  2. No warming of the lower atmosphere and cooling of the upper.
  3. Satellites not measuring less heat escaping out to space at the particular wavelengths that CO2 absorb heat.
  4. The rise in CO2 in the atmosphere, new coral etc, not having the isotope normally released by fossil fuels.
  5. Day time temperatures warming either the same or more than night temps.
The opposite or lack of any of these would seriously call AGW into doubt. The presence of them all has only been attributed to increased GHG effects and the increasing amount of Carbon 13, which is released on burning fossil fuels. This indicates that the increase in GHGs is predominately human caused.

I stated that Science predicted over a century ago that increases in GHGs would produce global warming. Mankind has increased GHGs and the globe has warmed. That warming has all the signatures of an increased green house effect.

Why feel compelled to scratch around for several alternative theories to account for the evidence when the basic physics supports the one theory that all the world’s scientific academies and almost all the scientists researching and publishing in this field agree is the most likely?

The presence of them all only needs a single theory to account for them – AGW.

However the questioning Skeptic never replied. I don’t think that was because he suddenly found himself out of contact with civilisation in some remote part of the world like Milton Keynes, but more likely there was a head sized bucket of sand near by.

But another did try to debunk/disprove my list. But their criticisms showed that they needed several theories, some which seemed not exist or directly contradicted some of the evidence. It even seemed that special, as yet undiscovered, physics would be needed.

  1. No increase in ocean acidification.

There seemed some confusion over my choice of Ocean Acidification (OA) which is definitely increasing. OA has nothing to do directly with temperatures and therefore warming, but I was asked what would disprove AGW. AGW requires an increase in CO2 in the environment. Some people even deny this is the case. OA proves that there is a very measurable build up of CO2 in the environment, even more than that in the atmosphere because much more CO2 is absorbed by the oceans than remains in the air. So while I agree that OA has nothing to do with AGW the lack of it has everything to do with disproving it

  1. No warming of the lower atmosphere and cooling of the upper.

Of course the opposite of this is the case. Their rebuttal seemed to consist of an admission that water vapour had risen in the atmosphere and ocean heat content (OHC) had also risen. Since H2O is a GHG then a rise in lower tropospheric temps should be expected.

The problem with this logic is that there was no alternate theory to account for the rise in OHC. The only theory that we know that can account for the way the layers of the atmosphere are warming and cooling is AGW. This was predicted by the theory but was not confirmed until more recently. What has been found matches what was predicted and what should happen with an increased green house effect due to CO2 – not just an increase in water vapour.

  1. Satellites not measuring less heat escaping out to space at the particular wavelengths that CO2 absorb heat.

Satellites do of course measure less escaping heat at the wavelengths of CO2. The best rebuttal of this was a claim that CO2 and water vapour have very similar 'absorption' wavelengths - could we actually state with any certainty which might be causing this reduction?

But they do not have the same 'absorption' wavelengths. To suggest this is hoping for something that the actual evidence does not support. Satellites have detected a decrease in IR from space in EXACTLY the corresponding wavelengths attributable to CO2 – NOT water vapour and NOT any overlap that could confuse the two. This is now well established science supported with hard data and confirms predictions.

For their rebuttal to have any merit they need the satellites measuring heat escaping the earth to be mis-calibrated just so, and to give the effect the science has actually predicted while they are actually measuring H2O instead of CO2, and this mis-calibration hasn’t been noticed or apparently affected the rest of the absorption spectrum.

  1. The rise in CO2 in the atmosphere, new coral etc, not having the isotope normally released by fossil fuels.

We know that Carbon 13 is the isotope depleted in burning fossil fuels and the ratio of C13/C12 has been dropping as a result. The only defence they had against this was acceptance that mankind had increased carbon in the atmosphere with the suggestion that it was questionable if this actually made any significant difference. So basically they avoided the evidence by promoting another myth, that increased CO2, of whatever isotope, could not have the effect the physics supported.

            4.5       Increased CO2 would make no significant difference

Well it does make a difference in even simple classroom experiments. Simply doubling CO2 increases temps by about 1C. We do not know of any scientific mechanism or negative feed back ‘in the wild’ that would prevent this effect.

The rebuttal of this was a claim that no lab experiment has been devised that can replicate the complexity of nature. The way CO2 and water vapour might “respond in a non-closed, chaotic system is a million miles away from the lab.”

Of course they may respond differently in a chaotic system, and they. That is why there are uncertainties as to how much a doubling of CO2 will warm the globe – but at this stage there is NO uncertainty that warming won’t occur. Anything else would defy known physics.

The problem with their position is that you need to positively suggest the laws of physics as they work in a lab won’t work as expected in the real world. But using Occam’s razor which is most likely? Would a true sceptic select the least likely over the most likely to form an opinion they would feel comfortable defending?

There is no difference from this position and knowing that the speed of a ball dropped in an experiment can be measured in a lab, but then suggesting if dropped outside it might actually fall up! Or like a poison being developed in a lab that kills rats 100% of the time and scientists suggesting it might only be 90% effective in the real environment but ‘skeptic theory’ would actually need rats to thrive on the stuff.

Such arguments really need a ‘theory’ to suggest why Co2 will actually act in a different way to its established physical properties. To ignore it and suggest it must simply because that is what is needed to refute the science has no credibility.

The ‘classroom’ experiments do demonstrate the effect starkly and are similar to those that have been done for over a century based on the physics worked out by Fourier, Tyndall, Arrhenius and Chamberlin. Science needs to be totally wrong about how CO2 that traps heat in the environment compared to the lab if ‘skeptic science’ has any standing.

  1. Day time temperatures warming either the same or more than night temps.

We know this is not true and while checking the research to ensure I had the right of it (see: Braganza 2004, Alexander 2006, Zhou 2009), I also came across a paper by Braganza et al in 2003 which shows that winters are warming faster than summers.

The ‘skeptic’ theory used to refute this was similar to that used to dismiss warming of the lower atmosphere and cooling of the upper, namely that increases in water vapour, a GHG, in the atmosphere would lead to an increase in night time temps. They insisted that only “amplification through increased water vapour” would lead to this effect.

The ‘theory’ used to support this increase in water vapour was describes as;

A)Sun heats oceans, oceans heat atmosphere. Major solar forcing throughout 20thC.
B) atmospheric water vapour

But claiming this totally misses the point about day and night time temps. Water vapour does not behave differently as a greenhouse gas in daylight compared to the dark. The physics is simple – really simple – If warming can be attributed to an increased solar forcing then temperatures during the times when this happens, (the Day,) will increase on average more than when it doesn’t, (the Night). It doesn’t matter about any change in water vapour because it will just be as potent as a GHG day or night. Any increase it directly causes will be the same day or night. So how does standard physics cater for water vapour behaving differently, not only day and night but at opposite ends of the planet, summer and winter? There was no answer to that.

What we actually see is the day warming some, as you would expect with additional forcing in the ‘green house’ effect but nights warming more because this additional effect reduces the amount of heat loss during the night. There are no other candidates that would cause this observation. So if they are right there must be another, so far undiscovered mechanism that appears to defeat the laws of physics.

5.5       Major solar forcing throughout the 20th Century.

But I wanted to pursue the claim in their ‘theory’ that there was a MAJOR solar forcing during the 20th century. There hasn’t been one and the Sun has been very quiet during the first decade of the 21st so I wanted to see the evidence that shows that solar forcing during the 20th Century was stronger than normal natural variation, and some figures ( hopefully by a credible scientist or two) that determines how much additional heating this caused and how that can account for the measured temperature increase.

In the end no evidence was given but perversely a claim that to not accept there was major solar forcing meant that I was simply ignoring the evidence!

So I thought I’d look at the evidence on solar activity and presented it to support my point that the Sun wasn’t a good candidate for heating in oceans and atmosphere.

I found this graph here;

It shows the number of sunspots during the twentieth century (considered to relate to solar intensity). The peaks during the last three decades are not even as high as those of the 50s – 60s. I can’t find a graph with trend lines but by eye it looks like a decline from the 60s just when global temperatures really started to increase last century. There is a clear lack of it in recent times. They have correlated in the past so what driver could have broken this trend? Believe it or not, the vast majority of publishing climatologists have a theory with a high degree of certainty.

As to some real evidence of how much solar has increased temps, I found a whole list of science papers;

Benestad 2009: "Our analysis shows that the most likely contribution from solar forcing a global warming is 7 ± 1% for the 20th century and is negligible for warming since 1980."

Lockwood 2008: "It is shown that the contribution of solar variability to the temperature trend since 1987 is small and downward; the best estimate is -1.3% and the 2? confidence level sets the uncertainty range of -0.7 to -1.9%."

Lean 2008: "According to this analysis, solar forcing contributed negligible long-term warming in the past 25 years and 10% of the warming in the past 100 years..."

Ammann 2007: "Although solar and volcanic effects appear to dominate most of the slow climate variations within the past thousand years, the impacts of greenhouse gases have dominated since the second half of the last century."

Foukal 2006:concludes "The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years."

This Skeptic needed many scientists being wrong about how much any change in solar output has added to current warming, which is now low.

Conclusion: Alternative ‘Theories’ and undiscovered physics.

Skeptics may actually believe that this series of misfortunate events has happened and real sceptics should find it more credible than a century old theory based on the basic physical properties of gasses that says if you increase GHGs in the atmosphere it should warm coupled with GHGs increasing and it warming.

So what really is most credible? Why do they think the science is so wrong on this one subject but trust it on every other subject that has fringe views like evolution, homoeopathy, MMR vaccines, age of the earth and the Big Bang etc.?

The inconvenient science remains. All the evidence from basic physics and heating patters in both daily and seasonal cycles in the atmosphere point to an increased green house effect caused by additional green house gases, particularly CO2 with satellite data clearly showing this is what has been restricting heat leaving the atmosphere, warming the troposphere and cooling the stratosphere.

Increased solar (even if it exists) and increased water vapour (that can only occur with an already warmed planet), have been investigated by many research papers and do not fit the evidence.

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