"The short answer to this question is no, since there is no official data that shows an increase in the frequency or intensity extreme weather events.
Nor is there any empirical evidence to link CO2 emissions to increased temperatures, although CO2 is a greenhouse gas (GHG) and does cause a modest amount of warming in the atmosphere.
The warming is expressed as how much temperature will increase if CO2 doubles and is known as the Equilibrium Climate Sensitivity (ECS)
but, according to the IPCC, it relies on positive feedbacks (i.e. anything that amplifies the initial warming such as an increase in water vapour) to have a major impact.
There are also negative feedbacks which have a cooling effect.
The IPCC estimates the sensitivity as between 2 and 5 degrees C and estimates the positive feedback to be about 300%.
Whilst no body disagrees with the basic premise of CO2 warming, there are questions to be asked about the sensitivity, the effect of feedbacks and the way the IPCC arrive at their figures.
The only correlation between the CO2 and temperature is between c.1975 and 2000.
(Obervations) should be enough to convince anybody that CO2 does not drive temperature rises, which have been described by the alarmist camp as unprecedented, using Michael Mann’s Hockey Stick graph to prove it.
But the Hockey Stick graph is now discredited ...
... the temperatures at the end of 20th C are not unprecedented.
So, what is the alarm?
The fundamental basis of the IPCC approach and which distinguishes the warming of the late 20th C from natural fluctuations are computer models but these can only be validated if they are able to replicate past fluctuations of temperature, (Taylor 2009, Sangster 2018).
The IPCC maintain that the spike in temperatures from 1975 – 2000 cannot be simulated in their models without GHGs and when they input GHGs their models simulate observed temperatures from 1975 – 2000 accurately.
However, when CO2 was not abundant enough to drive temperatures (1910 -1945) the models cannot reconstruct the temperatures as accurately which suggests that something else was driving temperatures at that time.
... not only do the models not replicate early 20th C warming but they cannot explain the ‘dimming’ from 1945 – 1975.
To explain this, and to explain why models were running hotter than observed temperatures during the pause in warming from c.2000, the modelers included sulphate aerosols from fossil fuel emissions into their models.
In 2013 the IPCC estimated the possibility of sulphates counteracting warming was from -0.4OC and -1.40C which essentially meant that any value in this range could be put into the models depending on their sensitivity.
If the sensitivity of a model was too high this could be offset by increasing the amount of sulphates and vice versa.
Climate models vary greatly in in estimating the ECS and only ‘replicate’ late 20th C temperature ‘by inferring whatever aerosol cooling effect is necessary’ (Johnston 2010 p.21).
The falsity of the sulphate cooling has been highlighted by Bjorn Stevens who compared the northern hemisphere and southern hemisphere temperatures rises from 1850 to 2010
and found they were very similar but he explained that the sulphate cooling should affect the northern hemisphere more as this is where most of the sulphates were produced.
No such differential was observed.
Stevens estimated that sulphate cooling was too large which is why models can’t get the cooling of the mid 20th C right.
This changing of a particular parameter (in this case sulphate aerosols) in the models which keeps the ECS within an ‘anticipated acceptable range’ is confirmed by an article entitled The Art and Science of Climate Model Tuning in The Bulletin of American Meteorological Society (March 2017).
However, this optimising of models to perform better on a particular metric related to specific goals is not how science should be done or how models should be evaluated according to Legates, (Heartland Conference, You Tube 2021).
Legates adds that because the models are used like this, the response of temperature to CO2 is NOT based on physics.
It is subjective with modellers choosing what they want to get the right output.
A doubling of CO2 does not double temperatures or cause temperatures to rise linearly because of the structure of the CO2 molecule which affects temperature logarithmically.
There comes a point where adding more CO2 to the atmosphere has no more ‘warming power’ (Taylor 2010 p.42).
The work of Jack Barrett at Imperial College, London, determined how much infrared radiation will be absorbed and transmitted at specific wavelengths and a doubling of CO₂,
according to Dr Barrett’s calculations, will result in an increase of absorption by CO₂ of just 1.5%.
This would suggest that the values in the IPCC General Circulation Models of between 2 – 5 degrees C are much too high.
Similar conclusions have been drawn by others with expertise in spectroscopy.
Using an increase in atmospheric CO₂ concentration from 290 to 385 ppm between 1880 and 2010, Professor Laubereau and Hristo Iglev calculated a temperature rise attributable to CO₂ of about 0.26 °C.
When the feedback effect of atmospheric water vapour was included, they concluded that CO₂ contributed somewhat less than 33% of its reported contribution to global warming.
The ECS not only depends upon a doubling of CO2 but relies on positive feedbacks to amplify an initial small temperature rise due to a doubling of CO2.
That is to say, as temperatures rise due to increases in CO2 more water vapour will be produced and because this is a GHG, it will amplify the initial temperature rise.
This is known as a positive feedback but it is unproven and indeed, Dr. Richard Lindzen has argued that more vapour in the atmosphere will lead to more clouds which can have a cooling effect.
The question then becomes how big are the positive and negative feedbacks?
The IPCC calculates positive feedbacks to be 3x but there is no scientific or theoretical basis for this assumption.
It is only what is thrown up out of the models. However, there is huge uncertainty about negative feedbacks, particularly the role of clouds which is still not understood fully.
Climate models are the basis of the IPCC work but are unreliable in predicting future temperatures.
Johnston 2010 cites research by Roe and Baker who show that high temperature increases are not an output of climate models but are in fact an input – a direct consequence of the assumption of a large positive feedback.
Tisdale (2015) cites the Summary for Policymakers 5th Assessment Report: No best estimate for equilibrium climate sensitivity can now be given because of a lack of agreement on values across assessed lines of evidence and studies. (IPCC 2013)
The ECS is the basis of the alarm that has swept the world but remember that if models cannot replicate earlier climates,
they cannot predict future climates and cannot be verified
and are therefore invalid and on these two factors the models fail.
The inadequacy of the models is also seen in discrepancies between them and observed temperatures, not least the hiatus or plateauing of temperatures after c.1998 until the present (2021).
Many people will be surprised to hear that there has been no significant rise in global surface temperature for 20 years (until 2021) and this is not predicted in any model.
Discrepancies between models and observations was first raised with regard to temperatures in the tropical troposphere where due to the lapse rate (rate of cooling as moist air rises),
according to the models, surface warming should be amplified in the troposphere
and this is one of the ‘central empirically testable propositions generated by climate models’ (Johnston 2010 p.19).
However, no such rise in the tropical troposphere temperature has been observed and the IPCC has admitted that the reasons for this discrepancy are ‘elusive’ (IPCC 2013).
Another discrepancy is that computer models are also programmed to predict a constant water vapour relative humidity in the upper troposphere (8 –12 km) above the tropics as CO2 increases.
Observations show that relative humidity in the upper troposphere above 8km has fallen by 9% since 1960 and this would mean the feedback effect on temperatures from a doubling of CO2 would be significantly less that the models predict.
The following graph from Dr John Christy and published on Dr. Roy Spencer’s website shows how wrong the models are.
Figure 4. 73 models versus satellite and weather balloon observations in the tropical mid-troposphere.
Graph originally by Dr. John Christy.
Now in what universe do the above results not represent an epic failure for the models?
I frankly don’t see how the IPCC can keep claiming that the models “are not consistent with” the observations.
Any sane person can see otherwise.
In conclusion the basis of predictions of climate catastrophe are based on models with built in assumptions about feedbacks which have no scientific base.
Models must be verified and validated against physical evidence.
The ability of a model to recreate the late 20th C warming does not show us that the model has accurately measured feedbacks that will determine the ECS to increases in CO2
and their predictions are meaningless unless they are confirmed by physical evidence which has not yet been done.
Further, it must be emphasised that there are no statistical links from official datasets that connect extreme weather and CO2 emissions or increases in the intensity or frequency of droughts, floods and hurricanes.
Climate crisis?
What climate crisis?
References:
Johnston, J.S. (2010) Global Warming Advocacy Science: a Cross Examination. Research Paper 10-08. Available at: http://ssrn.com/abstract=1612851
NOAA GFDL (2019) Transient and Equilibrium Climate Sensitivity. https://www.gfdl.noaa.gov/transient-and-equilibrium-climate-sensitivity/
Sangster, M. J. (2018) The Real Inconvenient Truth. Its warming but it’s not CO2. Printed in the USA
Spencer, R. (2013) STILL Epic Fail: 73 Climate Models vs. Measurements, Running 5-Year Means http://www.drroyspencer.com/2013/06/still-epic-fail-73-climate-models-vs-measurements-running-5-year-means/
Taylor, P. (2009) Chill. A reassessment of global warming theory. Clairview Books, East Sussex
Tisdale, B. (2015) On Global Warming and the Illusion of Control. Part 1. Advance Pre- Edit Copy.