Wednesday, 2 October 2019

Climate change solely due to CO2 changes. Unless we say it isn't.

From Watts Up With That:

The relative proportions of carbon dioxide and oxygen have varied very widely over the geological ages. It will be seen that there is no correlation whatsoever between carbon dioxide concentration and the temperature at the earth’s surface.

The alarmist rebuttal from Skeptical Science does not appear to dispute the actual facts from the first article, but:

Atmospheric CO2 levels have reached spectacular values in the deep past, possibly topping over 5000 ppm in the late Ordovician around 440 million years ago. However, solar activity also falls as you go further back. In the early Phanerozoic, solar output was about 4% less than current levels...

What about times closer to home? The last time CO2 was similar to current levels was around 3 million years ago, during the Pliocene. Back then, CO2 levels remained at around 365 to 410 ppm for thousands of years. Arctic temperatures were 11 to 16°C warmer (Csank 2011). Global temperatures over this period is estimated to be 3 to 4°C warmer than pre-industrial temperatures. Sea levels were around 25 metres higher than current sea level (Dwyer 2008).

If anything, that disproves a CO2-temperature link. If there were one, then it would be 3C warmer than it actually is. And why was there no 'runaway global warming caused by feedback effects' last time CO2 levels were this high? Because there is no such thing, it is a physical impossibility, like a perpetual motion machine.

If climate scientists were claiming CO2 was the only driver of climate, then high CO2 during glacial periods would be problematic.

That is exactly what they are claiming and it is problematic.

But any climate scientist will tell you CO2 is not the only driver of climate... Past periods of higher CO2 do not contradict the notion that CO2 warms global temperatures. On the contrary, they confirm the close coupling between CO2 and climate.

DoubleThink at its best. CO2 is main driver unless it's something else. Lack of correlation confirms correlation. There is a close coupling unless there isn't. They are truly making it up as they go along.

Read the articles, the first one might well be all lies and propaganda funded by Big Oil, but it is internally consistent, coherent and plausible. The second article ties itself in knots, leaving the reader none the wiser but with the impression that it's a load of rubbish.


Penseivat said...

I read somewhere that whenever a volcano erupts, it puts more CO2 into the atmosphere than mankind has, ever. Perhaps it's volcanoes we should ban?

Mark Wadsworth said...

P, I have read that this is a wild exaggeration at best.

Sobers said...

One of my 'go to' arguments over global warming is that all the CO2 from fossil fuels we are now burning was once in the atmosphere, before it was sequestered as dead animals and plants in the ground. Fossil fuels were not created with the Earth in the big bang, they were created from the available resources within the Earths functioning biosystem. So if it was in the atmosphere then, and didn't result in a runaway global warming catastrophe, why should it matter if we release it back there?

Mark Wadsworth said...

S, I have never dared put this point to an Alarmist. What sort of response do you get?

Unknown said...

S, there's quite a lot of evidence that fossil fuels were created with the Earth in the Big Bang.

OTOH, there's also quite a lot of evidence that high CO2 levels are caused by higher temperatures, not the other way around and a much more scientifically convincing mechanism as to why this should be so.

Physiocrat said...

If my calculation is correct, all the carbon dioxide in the atmosphere would form a layer just over 3 metres thick at 15 degrees C and a pressure of 76 cm mercury.