Dear All:
Several clarifications seem to be needed in this discussion. I offer the following.
Anthropogenic (i.e. man-made) global warming (AGW) stopped in 1998
Recovery from the Little Ice Age (LIA) halted in 1998 and global temperature has been almost stable since then. This recent global temperature stability is because warming of the northern hemisphere has been cancelled by cooling of the southern hemisphere in the global record.
AGW was supposed to be global, not hemispheric.
Nobody knows if the decade-long halt to global warming is temporary, but the following points warrant consideration.
Observation suggests there are several natural global temperature cycles that are overlaid on each other: and any global anthropogenic temperature effect must be overlaid on them.
One apparent cycle length is ~1500 years and since the time of Christ it has given us
the Roman Warm Period, then
the Dark Age Cool Period, then
the Medieval Climate Optimum, then
the Little Ice Age, and
the Present Warm Period.
Another apparent cycle length is ~60 years so globally there was
cooling to ~1910, then
warming to ~1940, then
cooling to ~1970, then
warming to 1998, followed by
no significant warming or cooling.
Is anthropogenic warming preventing the 30 years of global cooling that the 60-year cycle could be expected to provide from ~2000?
Or
Has the 1500 year cycle reached its peak so another long cooling trend is about to start?
Or
Is the apparent existence of the cycles an effect of randomness or of something else?
Or ….
Possible answers to these and similar questions deserve serious investigation.
What one can say is that the basis of AGW theory is challenged by the existing trends. AGW-promoters have repeatedly suggested that there would be a global warming trend with variable rate: none of them suggested there would be no global warming for a decade while one hemisphere cooled and atmospheric carbon dioxide concentration increased by ~5% (as has happened).
Keenselyside et al. say global warming will restart in 2015
The issue is simple. It is like this.
A horse-racing tipster predicted a horse would win the Derby, but that horse came last. Then, the tipster said he had amended his method and – using his amended method – he was confident that the same horse would win the Derby next year. Would anybody other than a fool believe him?
Now, compare that to the following.
Several teams made climate models and all those models predicted global warming with increased atmospheric carbon dioxide concentration. None – not one – of those models predicted that global warming would peak in 1998 then stop for the following decade despite atmospheric carbon dioxide concentration increasing by ~5%. But that is what has happened.
Now, one team has amended their model so it shows the cessation of global warming in 1998. Their amended model predicts that global warming will re-start in 1915. Does anybody other than a fool believe them?
Global cooling from ~1940 to ~1970 was induced by sulphate aerosols
The suggestion that sulphate cooling masked AGW warming for ~30 years after 1940 is an excuse that cannot be correct because of the warming effects of sulphate aerosols combined with soot particles.
My peer review for the most recent report (AR4) of the UN’s Intergovernmental Panel on Climate Change (IPCC) included the following comment on both drafts;
“Page 1-25 Chapter 1 Section 1.5.11 Line 30
For accuracy and completeness, after “… burning of fossil fuels” add “Additionally, it has been found that increases to sulphate aerosols combined with soot particles have a strong warming effect (0.55 Wm-2) greater than that of methane (0.48 Wm-2), and these combined particles are also linked with the burning of fossil fuels (ref. Jacobson MZ, Nature, vol. 409, 695-697 (2000)).””
But the published IPCC report was not amended in the light of my review comment.
Global climate models
It is not possible to do a physical lab. experiment that would demonstrate the temperature response of the Earth to a change in atmospheric carbon dioxide concentration. Such an experiment would require construction of a physical model of the entire Earth/ocean/atmosphere/biota system. Clearly, such a physical model is (and probably always will be) impossible.
However, general circulation models (GCMs) are computer models that are purported to be representations of the system. And “experiments” are conducted using these models to determine indications of the temperature response of the Earth to a change in atmospheric CO2 concentration. Personally, I think the claim that the GCMs are adequate representations is daft (the climate system is more complex than the human brain that nobody claims to be able to model).
The UN’s IPCC et al. assert the existence of ‘radiative forcing’ that – they say – governs all global temperature changes. This concept of ‘radiative forcing’ enables them to assert that GCMs can (and do) indicate the temperature response of the Earth to a change in atmospheric CO2 concentration.
‘Radiative forcing’ is inadequately defined but (according to IPCC) it is usually taken to be a change in the net radiative flux at the tropopause (i.e. the top of the troposphere which is the lowest layer of the atmosphere). Positive radiative forcing means rising global temperature and negative radiative forcing means falling global temperature.
If you think this explanation of GCM “experiments” is twaddle then I agree, but I am reporting what AGW-believers espouse.
One fact that I would point out is that the Sun has increased its output by ~30% in the 2.5 billion years since the Earth has had an oxygen-rich atmosphere. This is a ~30% rise in radiative forcing that has been provided by the Sun. So, if radiative forcing had a direct effect on the Earth’s surface temperature then the oceans would have boiled to steam long ago. Indeed, this fact alone should cause people to question the assertion that a postulated (e.g. by IPCC) increase of 0.4% to radiative forcing from a doubling of atmospheric CO2 concentration would have disastrous effects.
AGW-promotion is ‘religious’
I parodied this in the introduction to one of my presentations at the recent Heartland Institute climate conference in New York. Several of my contributions to the Conference in New York can be heard at http://www.heartland.org/NewYork08/audio.cfm
At the above URL an audio recording of the pertinent presentation can be heard by scrolling down to Tuesday 4 March, Session 8.45 – 10.15 am, Track 2 then clicking on Audio below my name.
Political motivations for AGW-promotion
I explain this in my responses to questions that can be heard by clicking on Audio after “Panel Q&A” at the bottom of the Session cited in the previous paragraph (above).
Evidence against the existence of AGW
Climate response to increased carbon dioxide in the air
There is no conclusive evidence that AGW is not happening. The existence of global warming (GW) is not evidence of anthropogenic – that is, man-made – global warming (AGW) because warming of the Earth does not prove that human activity warmed it. At issue is whether human activity is or is not affecting the changes to the Earth’s temperature that have always happened naturally.
But the fact that there is no conclusive evidence for AGW is not evidence that AGW is not happening. Simply, there is no conclusive evidence that AGW is happening, and there is no conclusive evidence that AGW is not happening, either.
However, it is known as a certain fact that the AGW projected by computer models of global climate (known as GCMs) is not happening. All the climate models show more warming in the upper troposphere than near the surface (especially distant from polar regions) as a result of increased radiative forcing from increased atmospheric greenhouse gas concentrations. However, measurements of temperatures in the troposphere (obtained from weather balloons) fail to show any such warming of the upper troposphere.
Nobody doubts that more CO2 in the atmosphere will increase radiative forcing, but AGW-proponents say this will cause the atmosphere to respond in a particular way. The pattern of the proposed response is a ‘fingerprint’ for AGW. Therefore, if that ‘fingerprint’ is absent – and it is absent – then any observed warming is not a result of the AGW they project.
We live in the troposphere, and the ‘fingerprint’ evidence is clear evidence that the man-made global warming projected by climate models is not happening.
Cause of increased carbon dioxide in the air
Atmospheric carbon dioxide concentration follows global temperature at all time scales
For example, Kuo et al. (Nature 393 (1990) ) showed that changes to the carbon dioxide cohere to the temperature changes and follow the temperature changes by months. Several other papers have since reported the same. . A cause cannot follow its effect but an effect may enhance its cause (i.e. positive feedback).
If human emissions of carbon dioxide were the direct cause of the recent rise in atmospheric carbon dioxide concentration then the clear evidence that carbon dioxide lags temperature at this time scale would not exist. This conclusion follows directly from the temperature-dependence of the carbon dioxide’s solubility in the oceans (cold water dissolves more carbon dioxide than warm water – as everyone who has opened a warm can of cola has discovered).
The anthropogenic emission fails to overcome the observed effect on atmospheric carbon dioxide concentration of the temperature-dependence of carbon dioxide’s solubility in the oceans. This failure of the anthropogenic emission to overcome the solubility effect is demonstrated by the fact that changes to the anthropogenic emission rate do not overwhelm the changes to the natural flux of carbon dioxide into the air: for example, the accumulation of carbon dioxide in the atmosphere continued when in two subsequent years the anthropogenic flux into the atmosphere decreased (as happened in the years 1973-1974, 1987-1988, and 1998-1999, for example).
Hence, since 1990 I have been proclaiming the following.
Anthropogenic global warming (AGW) presupposes that anthropogenic CO2 emissions are the direct cause of recent rise in atmospheric CO2 concentration. Hence,
1. the existence AGW would be denied if
2. rise in atmospheric CO2 concentration is natural and
3. the coherence of atmospheric CO2 concentration to global temperatue demonstrates that
4. rise in atmospheric CO2 concentration is natural
5. so the existence of AGW is denied by observations.
However, any imagined effect can be modelled in the absence of evidence of actual causal mechanisms. So, it is possible to model that the anthropogenic CO2 emissions are an indirect cause of recent rise in atmospheric CO2 concentration and this has been done (Rorsch A, Courtney RS & Thoenes D, ‘The Interaction of Climate Change and the Carbon Dioxide Cycle’ E&E v16no2 (2005)). I explained this in my presentation that can be heard at the URL I cite above.
Validity of the ‘Heartland List’ of scientists statements denying AGW
The list was complied by Marc Morano on behalf of the minority group of the US Senate Committee for Environmental Protection. Hence, the list is a political document.
Both the list and requests to be removed from the list need to be assessed in light of that knowledge.
The list provides quotations of individuals and says those quotations are against the AGW-alarmist consensus. As far as I am aware, all the quotations are accurate. (e.g. The quotes of my statements are accurate.)
I hope the above is helpful
Richard S Courtney
