I sit on the Board of a not for profit corporation that has both Canadian and Americans, and is composed of intelligent and accomplished people.
After altogether too many self-congratulatory asides on the issue of “climate change” by two of the members, I launched into an extended exposition of the arguments against man-caused climate change, which they were open-minded enough to endure.
80% of the time in the last billion years there has been no ice at the poles
Global CO2 has gone from 18% of atmosphere to trace amounts in a continuous step function decline over the past 30 million years, which geologists associate with the rise of the Himalayas as the Indian plate crashed into the Asian plate. Monsoon rains have leached out vase quantities of atmospheric CO2 as rainwater dissolves rock.
I live in a city that was under 4,000 feet of ice 11,000 years ago, and over 9,000 feet 21,000 years ago, so yes, there has been enormous natural global warming and cooling. We are in an interglacial period lasting about 10 to 15,000 years, which is nearing its end.
There is no reason to suppose the ice age in which we find ourselves has come to an end, and that the ice will fail to advance again.
Most measurements of global temperatures are proxies, no one actually recorded temperatures consistently until an English Quaker did so on the 1820s, and then only around Manchester, England. All other temperature records are inferences from proxies.
The Western Roman Empire and the period 1350-1850 were characterized by sudden climate worsening. Olives and vines grew as far north as southern Belgium in AD 400, by AD 425 that line was down south in Massif Central near Aix-en-Provence. The collapse of the Western Roman Empire can be attributed to sudden climate cooling forcing the Germanic tribes to move south into warmer climes.
It has got warmer since 1850 by a centigrade degree or two, which is what you would expect if you are coming out of a mini-ice age.
Current CO2 predictions vastly over-estimate the influence of CO2 in the climate models, for 18 or 22 years there has been no increase in average global temperature, despite the fact the atmospheric CO2 has grown past 400 parts per million.
To the extent that AGW was ever a scientific proposition, as opposed to a religious one, the “pause” is a powerful blow to the “anthropogenic” portion of global warming.
The Chairman looked at me with mouth agape. I do not think he had ever encountered a colleague disagree with the AGW consensus, in twenty years. It was his first encounter with a skeptic in a confined social space. He was polite enough to hear me out, to his credit.
No, I do not believe in man-made global warming. And I think the word “believe” is the correct one to use, because to the extent that global warming was ever a scientific proposition, that is to say disprovable – it has been very largely disproved.
I failed to mention that I do not know a geologist – which is to say a person concerned with very long periods of time – who takes AGW as anything other than a scientific fraud.
North America 18,000 years ago.