By Paul Homewood
Euan Mearns has a post up about the Geographical Society of London’s two recent Statements on Climate Change, which he has asked me to publicise:
Both statements by the Society centre around the contention that concentrations of CO2 and other gases in these bubbles follow closely the pattern of rising and falling temperature between glacial and interglacial periods.
They then go on to use this assumption to project large temperature increases as a result of higher emissions of CO2.
Euan forcefully points out the fundamental flaw in this argument, in his opening comment:
First of all I’d like to thank Dr Colin Summerhayes, his co-authors and the Committee of the Geological Society of London (GSL) for agreeing to this on-line discussion of The Society’s statement on climate change. However, I strongly disagree with much of its content.
The two main issues I have are as follows, which I will deal with in greater detail in separate comments. What I conclude from the data is that there are two strong forces that modulate historic climate cycles 1) Earth’s orbit, especially the 41,000 y obliquity cycle and 2) variations in the geomagnetic activity of the Sun resulting in quasi ~ 1,200 year cycles known as Bond or Dansgaard- Oeschger (DO) cycles (barely mentioned in the GSL statement but with more detail in the addendum). Most of the observed climate change of the Holocene can be attributed to this ~1200 year solar cycle. The action of these primary strong forces, mainly obliquity, causes climate to change and this in turn causes the greenhouse gas content of the atmosphere to change. Albedo of high latitude and high altitude areas also changes, via the formation and collapse of ice sheets. Green house Gases (GHG) and albedo may well cause positive and negative feedbacks but they are demonstrably weak forces easily overridden by the strong.
The general observation that GHG fluctuate with temperature over geological time needs to be interpreted with great care. The GSL Statement recognises the difference between cause and effect but then seems to lapse into the illogical position that GHG variations are primary causes of climate change. This is an illogical trap first created by Petit et al in their seminal paper on the Vostok ice core [1]. The fact that we currently have “unprecedented” 400+ ppm only has great significance if dCO2 is the primary cause of climate change which it has not been for the last 2.5 million years.
Ice cores
The GSL statement says this:
The concentrations of CO2 and other gases in these bubbles follow closely the pattern of rising and falling temperature between glacial and interglacial periods.
This is simply untrue. Petit et al recognise that this is untrue but then proceed with an interpretation that imagines that it is.
The Vostok Ice Core provides one of the finest geochemical records ever assembled and provides key data on what actually drives Earth’s climate in two ways.
1) At the glacial inceptions CO2 lags temperature by up to 14,000 years. This is a massive lag where full glacial conditions are established before CO2 begins to fall. This demonstrates that CO2 is not a significant driver of climate change during glacial periods. It simply follows temperature, closely at the terminations but with large time lags at the inceptions. The climate science community, starting with Petit et al, have simply brushed this key information under the carpet. The political, social and economic consequences of this error are too vast to imagine.
2) At the main turning points of the Vostok temperature curve, at the temperature high, CO2 reaches a maximum and albedo a minimum. If these variables were significant drivers it should simply continue to get warmer, but the exact opposite happens. The strong force – obliquity – simply sweeps these weak forces away. At the temperature minima, the opposite occurs. The stage appears set for the whole world to freeze, but what happens next is the ice sheets collapse.
The Sun
The GSL statement does not mention the role of the Bond / D-O cycles at all. It does say this:
In addition, the heat emitted by the Sun varies with time. Most notably, the 11-year sunspot cycle causes the Earth to warm very slightly when there are more sunspots and cool very slightly when there are few.
This is a gross misrepresentation of facts as they are understood. Bond cycles are recorded as cyclical variations in sediment composition in the North Atlantic. D-O cycles are recorded as temperature variations in Greenland, but not Antarctic, ice cores. Similar cycles are also recorded in carbonate stalactites in Oman. In every case, these cycles correlate with fluctuations in the cosmogenic isotope record, either 14C or 10Be. This tells us that it is variations in the geomagnetic field strength of the Sun that controls these climate cycles – NOT feeble variations in total solar irradiance stemming from sunspots!
The 2013 addendum does however correct this omission but does not present the cosmogenic isotope data faithfully:
Before the current warming trend began, temperatures in the Holocene (the last 11,000 years) were declining. This was due largely to insolation – the solar radiation received by the Earth’s surface – and dictated by the Earth’s orbit and the tilt of the Earth’s axis. Insolation declined throughout the Holocene. This cooling took Earth’s climate into a Neoglacial period, culminating in the ‘Little Ice Age’ (1450 – 1850).
The addendum goes on to say:
The changes in solar output can be detected via isotopes of carbon and beryllium produced in the upper atmosphere when solar activity is weak, and extracted from tree rings and polar ice cores 34. These fluctuations do not coincide precisely with palaeoclimatic events like the Medieval Climate Anomaly (although solar output was high during part of that time) or the Little Ice Age (during which there were some periods of minimal solar output).
This seems to be an attempt to undermine the veracity of the isotope record. Bond cycles do not leave a significant mark on global average temperatures. But, their action does cause climate to change everywhere. Some areas warm while others cool. This is most likely down to a change in the pattern of atmospheric circulation from zonal to meridional. Research from the UK Met office has shown how changes in the spectral output of the Sun can control the pattern of atmospheric circulation [2].
We know the more recent Bond cycles as the Roman Warm Period, Dark Ages cold period, The Medieval Warm period, the Little Ice Age (LIA) and the modern warm period. The LIA was not a single cold event during the Holocene but one of several cold events. The fact that the LIA ended was due to the Sun coming back to life and probably has nothing to do with CO2 at all.
Climate Sensitivity
Finally, I want to touch on climate sensitivity. The 2013 addendum says this:
Geologists have recently contributed to improved estimates of climate sensitivity (defined as the increase in global mean temperature resulting from a doubling in atmospheric CO2 levels). Studies of the Last Glacial Maximum (about 20,000 years ago) suggest that the climate sensitivity, based on rapidly acting factors like snow melt, ice melt and the behaviour of clouds and water vapour, lies in the range 1.5°C to 6.4°C.
This is a bizarre and astonishing claim. The main thing that strikes me is that climate science community doesn’t seem to have a clue about the impact of CO2 on temperature. 1.5˚C is probably harmless, perhaps beneficial. 6.4˚C probably catastrophic. This provides zero basis for energy policy development.
I suspect the reason for this chaotic message is that variations in glacial temperature have been wrongly attributed to variations in CO2, which as we have already established, varies in response to temperature. Temperature in turn results from changes in obliquity. Ice core data cannot be used to say anything about climate sensitivity.
A study of UK climate records I did jointly with Clive Best suggests climate sensitivity closer to a harmless 1.3˚C.
The full post can be read here.
I find it hard to believe that a team of supposedly top geologists have not been able to work this out for themselves. Instead they seem to have been blinded by global warming groupthink.
This paragraph from the 2010 Statement rather neatly sums up their false logic:
When was CO2 last at today’s level, and what was the world like then?
The most recent estimates [35] suggest that at times between 5.2 and 2.6 million years ago (during the Pliocene), the carbon dioxide concentrations in the atmosphere reached between 330 and 400 ppm. During those periods, global temperatures were 2-3°C higher than now, and sea levels were higher than now by 10 – 25 metres, implying that global ice volume was much less than today [36]. There were large fluctuations in ice cover on Greenland and West Antarctica during the Pliocene, and during the warm intervals those areas were probably largely free of ice [37,38,39]. Some ice may also have been lost from parts of East Antarctica during the warm intervals [40]. Coniferous forests replaced tundra in the high latitudes of the Northern Hemisphere [41], and the Arctic Ocean may have been seasonally free of sea-ice [42].
The clear logic is that temperatures then were the result of higher CO2 levels, and that we will likely see similar temperature rises now.
Yet it is well accepted that higher temperatures lead to higher concentrations of CO2 in the atmosphere.
Indeed, if the GSL’s logic was correct, we would have ended up with runaway global warming on many occasions in the past.
My understanding from Euan is that some of the geologists in the Society are actually very concerned about the Statements and fake science that lies behind them. So hopefully the more this issue is debated, the better it will be.
via NOT A LOT OF PEOPLE KNOW THAT
January 17, 2018 at 07:09AM
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