In the court summons of Urgenda (Dutch) the urgency based on their evidence is described. Interesting. I am always interested in the evidence. There was a time when I was looking closer for that “overwhelming” evidence of Catastrophic Anthropogenic Global Warming. I didn’t find hard evidence, but what I did find was an overwhelming repetition of assumptions.
This was no different: no hard evidence, but an accumulation building on a base assumption. It starts of course with this base assumption:
we emit CO2 → CO2 is a greenhouse gas → we are the main cause of the temperature increase
All nice and (much too) simple. Sure, CO2 is a greenhouse gas and the more in the atmosphere, the higher the temperature, other things being equal. Earth is a very complex system and elements it is composed of interact with each other. The big question is what the temperature impact of the human origin CO2 is in the real world. The IPCC (which their defense depends heavily on) even lowered the equilibrium climate sensitivity, going from 2 °C – 4.5 °C (best estimate of 3 °C) to 1.5 °C – 4.5 °C (no best estimate given). That is basically an uncertainty increase. But then they said they are even more sure now than ever before… That assumed certainty increase was being gloriously displayed in the court summons, mounting to the “overwhelming” evidence. The increased uncertainty was not acknowledged.
Temperatures went up in the last 100 years, but that doesn’t necessarily prove it is of human origin. And yes, the warming started in the 1850s, which coincide with the start of the industrial era. But it also coincide with the end of a cold period, the “little ice age”. When we came out of a cold period of 400-500 year, a 160 years of warming should not be that unusual. How to differentiate between the anthropogenic warming and a recovery from a cold period?
No mention that the “evidence” is obtained by climate models that don’t seem to be on par with reality. They act as if the climate models are correct and accurate. The pause in global temperatures learns us that there is a growing divergence between the models and observations and that should indicate we should have less confidence in them.
Do they have sound scientific evidence? Nope. Do they have a falsifiable theory? Nope. Do they have validated models? Nope. Were previous projections correct? Nope. Do they look at the different sides of the issue? Nope. In the end this is circumstantial evidence at best.