I often make a wager with my audiences. I will bet them that unless they are regular readers of the science-based climate sites, I can tell them something absolutely fundamental about global warming theory they have never heard. What I tell them is this:

Man-made global warming theory is not one theory but in fact two totally separate theories chained together. These two theories are:

1. Man-made greenhouse gasses, such as CO2, acting alone will warm the planet between 1.0 and 1.5 degrees Celsius by the year 2100.
2. The Earth’s climate system is dominated by positive feedbacks, such that the warming from Greenhouse gasses alone is amplified 3-5 or more times. Most of the warming in catastrophic forecasts comes from this second effect, not directly from greenhouse gas warming.

This is not some weird skeptic’s fantasy. This two-part description of catastrophic global warming theory is right out of the latest IPCC report. Most of the warming in the report’s forecasts actually results from the theory of positive feedback in #2, not from greenhouse gasses directly.

One of the most confusing issues for average people watching the climate debate is how one side can argue so adamantly that the science is “settled” and the other can argue just the opposite. The explanation lies in large part with this two-part theory.There is a high degree of consensus around proposition1, even among skeptics. I may disagree that the warming is 0.8C or 1.2C, but few on the science end of the debate would argue that CO2 has no effect on warming. When people say “the science is settled” they generally want to talk about proposition 1 and avoid discussion of proposition 2.

That is because proposition 2 is far from settled. The notion that a long-term stable system can be dominated by very high positive feedbacks offends the intuition of many natural scientists, who know that most natural processes (short of nuclear fission) are dominated by negative feedbacks. Sure, there are positive feedbacks in climate, just as there are negative feedbacks. The key is how these net out. The direct evidence that the Earth’s climate is dominated by strong net positive feedbacks is at best equivocal, and in fact evidence is growing that negative feedbacks may dominate, thus greatly reducing expected future warming from greenhouse gasses.

In my public presentations, I typically will

• Explain this split of catastrophic man-made global warming theory into two propositions, and how most of the predicted catastrophe comes from the second proposition rather than the first
• Show how skeptics have hurt their credibility by trying to challenge proposition #1
• Explain the mechanics in simple terms of positive and negative feedback
• Show the data and evidence related to feedback
• Show from historic temperature numbers that assumptions of high positive feedback are extremely unlikely to be correct.

I have a video related to these issues of feedback and forecasts on YouTube in a 9 minute video titled “Don’t Panic – Flaws in Catastrophic Global Warming Forecasts.”See all my videos at my YouTube channel.