We are given to understand that anthropogenic carbon-dioxide emissions will lead to increases in global temperatures, with potentially catastrophic consequences. But is this true? This claim consists of several parts,
1) That increases in atmospheric CO2 are anthropogenic;
2) That increasing CO2 leads to increases in global average temperature;
3) That an increasing global average temperature leads to changes which are severely adverse for human life.
Here I examine only the credibility of part (2). Specifically I examine the consensus view that doubling the CO2 concentration would lead to an increse in global average temperatures of about 2 deg.C.
To examine the claim requires a climate model capable of predicting average temperatures from the properties of carbon dioxide. Such models are usually extremely complicated. But in the pdf link below I construct a very simple model. It confirms the claims, albeit with strictly limited accuracy.
There are many counter-claims that the climate modellers have part (2) wrong. Many of these are based on a variant of the following fallacy: "CO2 is a greenhouse gas because it absorbs infrared radiation. This absorption is overwhelmingly most significant at wavelengths where the CO2 cross-section has resonance peaks. There is already sufficient CO2 in the atmosphere to absorb all the infrared radiation at these wavelengths. Consequently adding more CO2 cannot make any difference." The pdf link below explains why this argument is fallacious.
Both steps (1) and (3) may also be challenged. The concentration of CO2 in the atmosphere is easy to measure and has certainly been increasing fairly steadily for a long time. However, many credible scientists do not believe that this CO2 increase is anthropogenic. I do not address that issue here. But more contentious still is step (3). The claim that a 3 or 4 deg.C increase in global average temperature is severely adverse for human kind is entirely dependent upon climate models which are unverifiable and highly uncertain. Personally I have little faith in them. It is not even clear to me that, as regards the planet as a whole, a temperature increase of this magnitude might not be beneficial. (Inevitably, though, some regions would be adversely impacted). In particular, increased CO2 concentrations will improve the growth rate of most vegetation, with significant implications for feeding the world population.
To contact me go here
Go back to Rick's Physics Topic Selection Page
Go back to Rick's Home Page (Main Menu)
This is it - the place we're trashing - and again...
This is it - the place we're trashing