The Anthropogenic Global Warming Hypothesis (AGWH, for short) is simple, direct and appealing; the only problem is that it flunks the scientific method test, and I challenge any of its proponents - whether they are scientists or laymen - to prove otherwise.
In the most simple terms, the scientific method comprises basically: 1) the formulation of a hypothesis; and 2) the confirmation of the hypothesis by means of data observed in the real world. If the observed data do not fit the hypothesis, it must be reformulated or, eventually, abandoned. However, even when it is confirmed by a certain data set it is not uncommon that new ones fail to match it, resulting in the need of formulating a new hypothesis to account for them.
This is how science advances - and also the reason why scientists must remain permanently “skeptical” concerning the prevailing body of knowledge (so, every scientist worth of their salt is a skeptical, not only those who criticize the AGWH, as the “warmists” seem to think).
With that in mind, let’s examine the AGWH:
1) The hypothesis:
Mankind would be affecting (dangerously) the climate dynamics with its carbon emissions - specially CO2 - since the 18th century Industrial Revolution.
2) The needed proof:
In order to substantiate the AGWH, there would have to be some perceivable variations in the evolution patterns of climatic parameters, such as the temperature, or climate-influenced ones like the sea level, as compared to their behavior before the Industrial Revolution. That in such a way that the human influence after the 18th century could be clearly discerned. Such interference would reveal itself by means of unprecedented temperatures and sea levels and a positive acceleration of their variation rates, as compared to their patterns in the historical and geological past. These would be unquestionable “fingerprints”, as the “warmists” like to say.
3) The evidences:
According to the 2007 IPCC report (AR4), the global average atmospheric temperatures have risen 0.8C and the global average sea levels have risen 0.2 m (about 8 inches) since the late 19th century. It turns out that during the Holocene, the 12,000 year-old geological epoch in which Civilization has been existing, there have been several periods with temperatures and sea levels higher than the present ones. For instance, in the Middle Holocene, around 5,000-6,000 years ago, the sea levels were up to 3 meters higher and the average atmospheric temperatures were 2-4C higher than the current ones.
Also, the so called Medieval Warming Period occurred between the 10th and 13th centuries A.D., when temperatures were 1-2C higher than the current ones.
As to the variation rate of those indicators, the temperature rise since 1870 means an average rate of less than 0.6C per century. Well, just before the beginning of the Holocene 12,900 years ago, when the Earth was recovering from the last Ice Age, the temperatures fell again suddenly and a very cold period (called the Younger Dryas) ensued and lasted for some 1,300 years before the temperatures rose again to reach the levels prevailing during the Holocene. In both transitions from warming to cooling and from cooling to warming conditions, the temperatures fell and rose between 6-8C in just a few decades, a rate one full order of magnitude faster than the one of the latest 140 years (it clearly indicates that the Earth can go without the contribution of the human carbon emissions in order to produce such extreme climatic oscillations).
The same can be observed in the sea level, which rose 130 meters since the peak of the last glaciation 22,000 years ago. Most of this elevation occurred between 18,000 and 6,000 years ago, when there was a rise of 120 meters - an average rate of one meter per century, seven times faster than the recent rising rate and fast enough to make quite an impression on all the ancient peoples who inhabited the continental shores (it is not a coincidence that many of them had legends about a world deluge).
All this can be inferred from geological, geomorphologic, glaciological, oceanographic, biological, archeological and historical evidences from all continents (the excellent www.co2science.org website provides an easy access to hundreds of such studies).
Hence, the big question: if in the Middle Holocene, when dung and firewood were the only fuels used by Mankind and the world population was at least two orders of magnitude smaller than today’s, there were temperatures and sea levels considerably higher than the present ones; if the atmospheric warming at the end of the Younger Dryas 11,600 years ago and the sea level rise between 18,000 and 6,000 years ago were much faster than the observed since the 19th century; so, where are the evidences that would allow us to point to the “human fingerprint” in the small variations of the latest 140 years, against the background of the much wider and faster natural oscillations of the historical and geological past?
The answer is: there aren’t any (for evidences I mean, obviously, hard facts observed in the physical world, not mathematical concoctions extracted from the climate models).
The AGWH has no support in the real world evidences. Hence, the political agenda of changing the entire energy basis of the world economy, which is 80%-plus dependent on fossil fuels, is misguided, to say the least, and misanthropic at the worst. So, its real motivations must be looked for in quarters other than real science.
Geraldo Luis Lino is a Brazilian geologist and author of the book “The Global Warming Fraud: How a Natural Phenomenon was Converted into a False World Emergency” (published in 2009 in Portuguese, with over 5,000 copies sold so far, and soon to be published in Spanish in Mexico)