Prof. Bob Carter, an Aussie scientist, gives a very good summary of why the theory of Anthropogenic Global Warming (AGW) has failed. That theory has at its heart the hypothesis that carbon dioxide is the biggest driver of our climate and that, as carbon dioxide increases in the atmosphere, our temperatures will warm proportionately. This from a post by Prof. Carter at WUWT:
Though you wouldn’t know it from the antagonistic nature of public discussions about global warming, a large measure of scientific agreement and shared interpretation exists amongst nearly all scientists who consider the issue. The common ground . . . includes:
· that climate has always changed and always will,
· that carbon dioxide is a greenhouse gas and warms the lower atmosphere,
· that human emissions are accumulating in the atmosphere,
· that a global warming of around 0.5OC occurred in the 20th century, but
· that global warming has ceased over the last 15 years.
The scientific argument over DAGW is therefore about none of these things. Rather, it is almost entirely about three other, albeit related, issues. They are:
· the amount of net warming that is, or will be, produced by human-related emissions,
· whether any actual evidence exists for dangerous warming of human causation over the last 50 years, and
· whether the IPCC’s computer models can provide accurate climate predictions 100 years into the future.
. . . My answers would be: insignificant, none and no.
What can possibly explain such disparate responses to a largely agreed set of factual climate data?
. . . Given the great natural variability exhibited by climate records, and the failure to date to compartmentalize or identify a human signal within them, the proper null hypothesis – because it is the simplest consistent with the known facts – is that global climate changes are presumed to be natural, unless and until specific evidence is forthcoming for human causation.
It is one of the more extraordinary facts about the IPCC that the research studies it favours mostly proceed using an (unjustified) inversion of the null hypothesis – namely that global climate changes are presumed to be due to human-related carbon dioxide emissions, unless and until specific evidence indicates otherwise.
What hypothesis do we wish to test?
. . . The DAGW hypothesis that I want to test here is precisely and only “that dangerous global warming is being caused, or will be, by human-related carbon dioxide emissions”. To be “dangerous”, at a minimum the change must exceed the magnitude or rate of warmings that are known to be associated with normal weather and climatic variability.
What evidence can we use to test the DAGW hypothesis?
Many different lines of evidence can be used to test the DAGW hypothesis. Here I have space to present just five, all of which are based upon real world empirical data. For more information, please read both Dr. Hayhoe’s and my book.
Consider the following tests:
(i) Over the last 16 years, global average temperature, as measured by both thermometers and satellite sensors, has displayed no statistically significant warming; over the same period, atmospheric carbon dioxide has increased by 10%.
Large increases in carbon dioxide have therefore not only failed to produce dangerous warming, but failed to produce any warming at all. Hypothesis fails.
(ii) During the 20th century, a global warming of between 0.4O C and 0.7O C occurred, at a maximum rate, in the early decades of the century, of about 1.7O C/century. In comparison, our best regional climate records show that over the last 10,000 years natural climate cycling has resulted in temperature highs up to at least 1O C warmer than today, at rates of warming up to 2.5O C/century.
In other words, both the rate and magnitude of 20th century warming falls well within the envelope of natural climate change. Hypothesis fails, twice.
(iii) If global temperature is controlled primarily by atmospheric carbon dioxide levels, then changes in carbon dioxide should precede parallel changes in temperature.
In fact, the opposite relationship applies at all time scales. Temperature change precedes carbon dioxide change by about 5 months during the annual seasonal cycle, and by about 700-1000 years during ice age climatic cycling. Hypothesis fails.
(iv) The IPCC’s computer general circulation models, which factor in the effect of increasing carbon dioxide, project that global warming should be occurring at a rate of +2.0O C/century.
In fact, no warming at all has occurred in either the atmosphere or the ocean for more than the last decade. The models are clearly faulty, and allocate too great a warming effect for the extra carbon dioxide (technically, they are said to overestimate the climate sensitivity). Hypothesis fails.
(v) The same computer models predict that a fingerprint of greenhouse-gas-induced warming will be the creation of an atmospheric hot spot at heights of 8-10 km in equatorial regions, and enhanced warming also near both poles.
Given that we already know that the models are faulty, it shouldn’t surprise us to discover that direct measurements by both weather balloon radiosondes and satellite sensors show the absence of surface warming in Antarctica, and a complete absence of the predicted low latitude atmospheric hot spot. Hypothesis fails, twice.
. . . .
The current scientific reality is that the IPCC’s hypothesis of dangerous global warming has been repeatedly tested, and fails. Despite the expenditure of large sums of money over the last 25 years (more than $100 billion), and great research effort by IPCC-related and other (independent) scientists, to date no scientific study has established a certain link between changes in any significant environmental parameter and human-caused carbon dioxide emissions. . . .
My one caveat to Dr. Carter's summary would be that I have zero trust in the assertion that any warming has occurred in the 20th century, simply because I do not trust the temperature records maintained by global warming theories high priest, James Hansen. Hansen has modified our temperature records on more than one occasion, always reducing older temperatures from the early and mid 20th century while increasing modern temperatures. He should be in jail.