Do you know what a "Straw Man Argument" is? It's when you present your opponent's view point, as something it is not. Preferably, something absurd. That's the "StrawMan". Then, you attack the strawman, that you have created. When you're done taking that strawman apart, you claim that you've won the argument. It's a time honored technique, one that debaters and lawyers have known for centuries. Let's take a look at how deniers have used this to deceive people. Here we're looking at the ice core record from the Vostok, In the red we see temperature going up from early time to later time at the very key interval when we came out of the glaciation. And we see the tempareture going up. And then we see CO2 coming up. CO2 lags behid that increace. It's got a 800 year lag so temparature is leading CO2 by 800 years. So the fundamental assumption, the most fundamental assumption of the whole theory of climate change through the humans, is shown to be wrong. The strawman here, is that, "Climate Scientists say "Throughout history, CO2 has always and in every case been the single controlling factor of global temperature.
" The reason that's a strawman is, Nobody says that. Ever since scientists realized that the earth's ice sheets have expanded and contracted many times over the last 3 million years, they have wondered what would possibly have been the cause of these grand climatic cycles. We're reasonably sure it's not this. By the 1970s, Several peer reviewed studies confirmed the current view that long term changes in earth's orbit and rotation have been the timer, the initial forcing, that move the planet in to, and out of, glacial periods. They were named, "Milankovitch Factors", after Milutin Milankovitch, the Serbian Mathematician who first advanced the theory. There are 3 main factors. The first one is precession. This refers to a slow change in the direction of the earth's axis of rotation, much like a rotating top. The process takes about 22,000 years. The second factor, is Obliquity. Obliquity is the subtle change in the actual angle of the axial tilt, from 22.
1 degrees, to 24.5 degrees, which occurs over about 41,000 years. The third, is Eccentricity, in which the shape of earth's orbit changes from nearly circular, to more elliptical, or egg shaped, over about 100,000 years. The cycles sometimes work together, and sometimes cancel each other out. but the end result is, about every 100,000 years, the planet goes into, and out of, a glacial period, what we call, an ice age. The last time they were in effect, they helped take us out of an ice age, from 20,000 to 11,000 years ago. They will not be significant again until 20 to 30,000 years in the future, when another major cooling will begin. But there were some weaknesses in the theory. In the 80s and 90s, scientists like James Hansen of NASA, and others, worked to understand how such a relatively weak forcing could cause the kind of major global changes that would produce large planetary effects.
They understood that other factors were at work to amplify the change. For instance, changes in snow and ice cover, alter the absorption of heat, amplifying the temperature change. But how could changes taking place primarily in the northern hemisphere be spread over the whole planet? The missing link, they said, was that the increased warming of water and soils released greenhouse gases, CO2 and Methane. Hansen and his group wrote in 1990 – "Changes in CO2 and methane content have played a significant part in the glacial-interglacial climate changes by amplifying, the relatively weak orbital forcing and constituting a link between Northern and Southern Hemisphere climates." To prove the truth of this sequence of changes, Hansen and his team called for more ice core studies, and more accurate measurements. It is these studies that have given us enough detail to show whether Hansen was right about greenhouse gas effects. And, these very studies are the ones Deniers have chosen to cherry pick and distort.
Those who have watched this series for a while know that I always like to go to the source of any claim that climate deniers make, in this case, a study by Nicolas Caillon, published in Science, in March of 2003, which of course, we'll actually read. It's titled "Timing of Atmospheric Co2 and Antarctic Temperature changes across Termination 3" "Termination three" refers to the warming that brought the planet out of a previous glacial period, 240,000 years ago. What the graph shows is good support for Milankovitch theory, as well as Hansen's prediction. Orbital factors begin a long slow warming trend, which causes the outgassing of CO2 and methane from oceans and soils, reinforcing and amplifying the weak orbital warming, and creating dramatic global change. The study says: "The sequence of events is in full agreement with the idea that CO2 plays, through its greenhouse effect, a key role in amplifying the initial orbital forcing.
" And. "The situation at Termination III is different from recent anthropogenic CO2 increase" "we should distinguish between internal influences (such as the deglacial CO2 increase) and external influences (such as the anthropogenic CO2 increase) on the climate system" "Althou recent CO2 increase has clearly been imposed first, as a result of anthropogenic activities, it naturally takes, at Termination III, some time for CO2 to outgas from the ocean once it starts to react to a climate change that is first felt in the atmosphere." and finally, "the sequence of events during this Termination is fully consistent with CO2 participating in the latter 4200 years of the warming." The radiative forcing due to CO2 may serve as an amplifier of the initial orbital forcing, which is then further amplified by fast atmospheric feedbacks that are also at work fot he present and future climate." Could they have made it any clearer? Let's review. We know that orbital forces have not acted significantly in 10,000 years, nor will they for another 30,000. We know that the sun has not been a significant factor in the last 50 years. We've seen how James Hansen and his team predicted the interplay of orbital effects and greenhouse gases 10 years before the actual data became available.
And we've seen how the very study climate deniers hope you won't read, is used to twist and distort the debate, when in fact, it proves how well climate scientists have understood and predicted Greenhouse effects. The majority of climate deniers are unknowing pawns who have been manipulated by fear, and ignorance to continue spreading a few carefully crafted propoganda memes. As I've studied this debate, the wonder has always been, the depths of dishonesty and cynicism that are common practice among the paid professional denier community. Let's continue to cut through the ignorance, and spread the truth, right here, every week..