An argument regularly advanced by alarmists is – can we afford to take the chance? This argument is often associated with a claim that a rise in global temperature greater than 2°C would be catastrophic – a theory backed by authoritative sounding computer simulations which suggest dangerous ocean acidification, deadly heat, and extreme weather.
It is all very well to simulate these scary possibilities, but at the end of the day a computer simulation is just an educated guess – it is no substitute for observation.
Wouldn’t it be great if there was a way to actually observe what a warmer world would actually be like? What if it were possible to create a parallel Earth, dial up the CO2 level, and actually see what really happens? Would anyone bother running a computer simulation, if we could observe the reality?
We can’t create a new planet, but there is a way we can observe the effects of elevated levels of CO2, and higher global temperatures, without relying on computer simulations – because these are the conditions which prevailed during the Cretaceous Period, the age of the dinosaurs.
According to Wikipedia,
“The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels and creating numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, while dinosaurs continued to dominate on land. At the same time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a large mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs and large marine reptiles, died out. The end of the Cretaceous is defined by the K–Pg boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.”
According to Wikipedia, the mean global temperature during the Cretaceous was 18c, 4c higher than today’s global temperature. The CO2 level in the Cretaceous was around 1700ppm, over 4x higher than today’s 400ppm.
Was the Cretaceous too warm for Earth’s diverse species? Absolutely not – the Cretaceous hosted a bounty of life and biodiversity, the emergence of the first flowering plants, the first appearance of our mammal ancestors. The Dinosaurs dominated the warm Cretaceous for 80 million years, a long period during which life flourished.
The event which finally brought this golden age of bounty and biodiversity to an end was the Cretaceous-Paleogene extinction event. This event had nothing to do with prevailing CO2 levels, the extinction event was a gigantic meteor impact, the site of which is believed to be a location in the Gulf of Mexico, an impact which produced a crater over 100 miles across, and blotted out the sun, spreading a thin layer of Iridium dust across the entire World.
What can we learn from the the Cretaceous? In my opinion, the lesson from the Cretaceous is – we have nothing to fear from CO2. And if our civilisation has any money to spare on preparations for possible disasters, we should be spending that money on building meteor defences, not on trying to curb harmless CO2 emissions.