Ian Plimer is Australia’s best known geologist. In retirement he is Emeritus Professor at the University of Melbourne where he was the head of Earth Sciences. He was an editor for a five-volume Encyclopedia of Geology and he has written ten books for general consumption including an international bestseller Heaven and Earth. This collection Climate Change: The Facts is dedicated to the late Bob Carter who had an outstanding career as a leader in the field of climate studies based in stratigraphy, palaeontology and marine geology.
A striking figure in Plimer’s chapter shows the changing composition of the earth’s atmosphere over the last four billion years. At the start methane 65% and CO2 35% shared the atmosphere. CO2 declined steeply as nitrogen appeared followed by water until two million years ago methane was effectively gone and CO2 was reduced to a trace gas as oxygen appeared. During the last million years nitrogen and oxygen filled the air with water as the major greenhouse gas and CO2 at 0.04%.
There was no runaway warming when CO2 exceeded 5% of the atmosphere so it is hard to account for serious warming while CO2 is a trace gas. There were higher temperatures in the past and Plimer provides a deal of argument and evidence to indicate that the cycles of temperature and the coming and going of ice ages did not correlate with the level of CO2. This is not in the paper but it is interesting that CO2 has been rising steadily through the last century but from the 1940s to the 1970s warming reversed, with a fear of disastrous cooling led by James Hansen. Then the warming resumed in parallel with CO2 through the period of model building in the ‘80s and ‘90s followed by the warming paused while the CO2 continued upward.
One of the alarmist refrains is that the contrarians are not real climate scientists. This is clearly not the case and Wikipedia has a list of scientists who deny the consensus. The list is not designed to enhance the reputation of “deniers” and it is headed by a chart to show how real climate scientists cleave to the consensus while others do not. Still there are undeniably genuine climate scientists on the list like Lindzen, Curry, Paltridge and Spencer and it is handy to have the full list at hand, including a category of dead scientists including Bob Carter.
The main point in Bob Carter’s paper is that the IPCC model-based narrative is rooted in 150 years of measurements supported by a range of proxies like tree rings and ice core samples extending back around 1000 years. “This is an utterly inadequate period over which to seek to understand climate change”.