In researching the post about the list of sceptical scientists I was set on a new course and discovered a couple of interesting facts in the TAR. The narrative describing the list referred to three statements from the 2001 Third Assessment Report (TAR) of the IPCC. The first is:
The global average surface temperature has risen 0.6 ± 0.2 °C since the late 19th century, and 0.17 °C per decade in the last 30 years.
The rise of 0.6 °C was unexceptional, but I wondered at the 0.17 °C because it represents a rate of recent warming nearly three times higher than earlier.
Maybe I just missed it before or I forgot it, but let’s check it anyway. The reference was IPCC, 2001: Climate Change 2001: Working Group I: The Scientific Basis.
The Summary for Policymakers (SPM) quickly confirmed the century-long warming of 0.6 °C on page 3:
Over both the last 140 years and 100 years, the best estimate is that the global average surface temperature has increased by 0.6 ± 0.2°C.
That left the more recent warming of 0.17 °C per decade, which I found in Chapter 2, Observed Climate Variability and Change, Table 2.2, p.115. However, the period is 1976–2000, 25 years, not the 30 years mentioned in the Wikipedia list. So it can be taken as a short-term movement, but does not qualify as establishing a trend. Still, that doesn’t stop the IPCC activists from thumping the table about accelerated warming.
I was somewhat intrigued to read in Chapter 1, The Climate System: an Overview, on page 96 (bold added):
Historically, human activities such as deforestation may have had a local or regional impact, but there is no reason to expect any large human influence on the global climate before the 20th century. Observations of the global climate system during the 20th century are therefore of particular importance. Chapter 2 presents evidence that there has been a mean global warming of 0.4 to 0.8°C of the atmosphere at the surface since the late 19th century. Figure 2.1 of Chapter 2 shows that this increase took place in two distinct phases, the first one between 1910 and 1945, and recently since 1976.
The first highlighted passage is a cute way of expressing a common sceptical viewpoint: that a human influence on the global climate has been undetectable so far—only it’s ironic the IPCC seemed to share that viewpoint back in 2001.
The second highlighted passage should be pressed long and strong throughout the land: the alleged unrelenting man-made global warming has not been continuous, as the increase in atmospheric CO2 has been continuous, but has happened twice. The first time was 100 years ago, from 1910 to 1945. The second time, from 1976 to 2000, didn’t even last the 30 years considered the minimum to declare a trend and ended between 17 and 20 years ago.
This man-made global warming lark is supposed to be caused by carbon dioxide, right? Let’s assume for a moment that it is, just for the sake of argument. The atmospheric concentration of CO2 has been rising pretty steadily since 1958, when C. David Keeling started measuring it at Mauna Loa. The concentration varies predictably each year in time with the northern seasons but within that it rises almost constantly.
However, in marked contrast, the global temperature fluctuates wildly and does not resemble the monotonic rise of the CO2 level.
The curves are so different that it’s simply impossible to believe that CO2 governs temperature or, for that matter, that temperature governs the release of CO2. Am I wrong?
If more people knew that the global temperature has not been rising steadily and has leaped just twice in 100 years, they would be free of the pervasive influence of the CO2-demonising zealots.
Does anyone remember that the impulse for the ingratiating and oh-so-credible good-looking young man preaching nightly on the television the virtues of saving energy was the desire to reduce our emissions of CO2? These days he couches his advice in terms of saving your money. Hah! Why does the government spend tens of thousands of your taxes every night to persuade you to save your money? Anyone see the irony of that?
What the government is actually doing is paying the price of a coalition government. The Greens managed to leverage their support into a few feel-good ‘climate’ programmes and that’s one of them.
Settled science? The only thing that’s settled is the deception that science has something to do with it.