Guest essay by Eric Worrall
CO2 forcing is logarithmic – the more CO2 you add, the less effect additional CO2 has on the climate system. So how do you make this diminishing return sound scary? By creating a fantasy, or course.
Near miss: the importance of the natural atmospheric CO2 concentration to human historical evolution
When fossil fuel energy was discovered, the timing and intensity of the resulting climate impacts depended on what the natural CO2 concentration in the atmosphere was at that time. The natural CO2 concentration is thought to be controlled by complex, slow-acting natural feedback mechanisms, and could easily have been different than it turned out to be. If the natural concentration had been a factor of two or more lower, the climate impacts of fossil fuel CO2 release would have occurred about 50 or more years sooner, making it much more challenging for the developing human society to scientifically understand the phenomenon of anthropogenic climate change in time to prevent it.
The crux of the argument appears to be the following;
… The set point of the CO2 thermostat depends on the intensity of sunlight received at the Earth’s surface, among many other things (Berner and Lasaga 1989; Berner 1997). According to the Berner formulation, if the temperature at the surface of the sun were just 1 % hotter, or if Earth were just a few percent closer to the sun, a significantly lower atmospheric CO2 concentration would have been needed, for weathering to balance the same rate of CO2 degassing (Fig 1a and b). A 10 % change in the albedo of the Earth, or in the age of the Earth (putting us later on the timeline of a warming sun), would also have had a significant impact on the steady state atmospheric CO2 concentration. The CO2 degassing rate could be a bit lower than it is. If any of these factors had been different at the time in Earth history when industrial society arose, the CO2 concentration in the atmosphere could have been much different than it turned out to be, either higher or lower. …
Read more: Same link as above
Essentially the author is arguing that if humanity had evolved millions of years later in our planet’s history, when the sun was a little warmer, we would have encountered serious climate problems decades earlier in our industrial history than today, and therefore have been a lot less able to deal with them.
The problem with this argument is, despite the author’s assertions, we still haven’t encountered any “challenging” problems with the global climate. Despite wild claims about climate refugees and worsening storms, the reality is the global climate is benign. Our biosphere is growing more productive, more benign, thanks to greening from anthropogenic CO2.
If the Earth really was currently experiencing major anthropogenic climate related problems, there would be no need to invent fantasies about how it could have been worse.