IPCC scientists fail yet again to justify global warming alarm
By Bryan Leyland & Bob Carter
The beguiling simplicity of the first sentence of an article in last week’s Dominion Post by Wratt, Reisinger & Renwick (WRR) about the IPCC’s view of climate change masks deep ambiguity and confusion about what precisely the dangerous anthropogenic global warming (DAGW) hypothesis is all about.
In that sentence WRR say that “Warming of the climate system is unequivocal, and human influence on the climate system is clear.”
The statement that warming of the climate system is unequivocal is disingenuous and ambiguous in equal measure, because whether the statement is true or not depends entirely on the time period considered.
For instance, mild global warming occurred between the end of the Little Ice Age (say 1860) and now, and also between 1979 and 1997. However, it is also true that cooling of a degree or two has occurred since the peak of the Mediaeval Warm Period (say 900 AD), and also since the Holocene Climatic Optimum about 8000 years ago.
Planet Earth is therefore clearly on a long-term cooling trend within which the 20th century multi-decadal warmings that so worry the IPCC represent weather variability and oceanographic-atmospheric oscillations more than they do long-term climate change.
It is also the case that no modern warming has occurred since 1997, an 18 year-long period during which atmospheric carbon dioxide levels increased by 10%. That 10% increase represents fully 30% of all the human-related emissions since the start of the industrial revolution – all for no warming, remember.
Which brings us back to the real hypothesis that we wish to test. It is not, as WRR seem to believe, that “warming of the climate system (is) happening” but specifically that “dangerous global warming will be caused by human-related carbon dioxide emissions”.
Science is about testing hypotheses, and the facts related above are a primary test of the DAGW hypothesis as just stated. The hypothesis fails that, and many other, empirical tests.
In addition, there is another primary hypothesis that WRR have failed to address, which is the simplest hypothesis that explains all the facts – called by scientists the null hypothesis. Given the highly variable nature of both weather and climate through time, the simplest hypothesis is that “observed modern changes in the climate system, or in plants and animals affected by it, are due to natural causes unless and until specific evidence indicates otherwise”. Neither WWR nor their favoured IPCC scientific sources describe any evidence whatever that invalidates that hypothesis.
WWR’s innocuous first sentence continues “…. human influence on the climate system is clear”.
Well, of course, for we can’t imagine a single scientist who would dispute that statement.
For example, the building of towns and cities alike replaces natural vegetation and land surfaces with industrial materials, thus providing a heat trap for solar radiation and causing the local warming that is termed the urban heat island effect. Similarly, in the countryside, farmers cut down dark-coloured native vegetation and replace it with light-coloured crops such as wheat. These fields now reflect more incoming solar radiation than did the native forest, which results in local, human-induced cooling.
Adding up the various human warming and cooling influences around the globe must result in a figure that represents the net human effect on global temperature. But the effect is so small that it has yet to be calculated accurately, let alone measured; indeed, we do not even know whether the net human effect worldwide is one of warming or cooling.
The issue then is not one of “is there human influence” on climate, but of “how great is the human influence and what sign does it have”?
As summarised in the reports of both the IPCC and NIPCC (Nongovernmental International Panel on Climate Change), thousands of scientists have expended hundreds of billions of dollars researching this question since 1988 (formation year of the IPCC) without any evidence emerging that the human effect rises above the noise in the global temperature signal, or that any of the manifold changes in the natural world around us today are being caused by human-related carbon dioxide emissions.
Given that it has taken us almost 600 words to dissect and correct just the single opening sentence of the WRR article, readers will appreciate that it would take nearly a book to adequately discuss, and in many instances correct, the remainder of their tendentious article.
For interested readers, we have provided a point by point commentary on the eleven points enumerated by WRR at this web address – http://tinyurl.com/kqwqusk Here, we conclude by offering just a brief summary statement of the remainder of the WRR article - which is this.
WRR (and the IPCC) present many statements of fact with which we, and many other scientists, agree. In interpreting those facts, however, WRR fail to deploy them to test the DAGW hypothesis, fail to negate the null hypothesis, often treat evidence in an anecdotal way, and reveal a partiality for adopting alarmist environmental projections from known-to-be-faulty deterministic computer models.
Bryan Leyland is an engineer who specializes in and writes about renewable energy matters. Bob Carter is a geologist and environmental scientist, and Chief Scientific Advisor to the International Climate Science Coalition. Both are also authors of the recent book “Taxing Air”, which discusses all sides of the global warming issue.