CO2: ‘primary trigger’ does not = ‘primary contributor’

The establishment media is falling over itself this morning to deny basic science, in its rush to find a way to condemn President Trump’s new Head of the EPA. Speaking to CNBC, Scott Pruitt said of carbon dioxide and its role in changing “the climate.”…

“I would not agree that it’s a primary contributor to the global warming that we see”

That statement is correct and is just basic science, as I understand it. Note also that he wasn’t being asked about ‘man-made climate change’, just about “the climate.” Full stop.

It’s sad that even AFP and Associated Press’s combined science correspondents appear to be totally clueless about the strong water vapour amplification effect — which climate science thinks is the primary contributor to the overall effect of global warming. When one knows about the amplification effect, a key part of the global warming process, then one can see that Pruitt’s careful wording in the key sentence of his reply doesn’t at all contradict the EPA’s key position statement that…

“Carbon dioxide is the primary greenhouse gas that is contributing to recent climate change.”

Because CO2 is “the primary greenhouse gas”. But primary as in ‘coming first in the process’. Being ‘the primary trigger‘ for a much larger amplification effect caused by water vapour (which even the EPA can’t bring itself to list as a “greenhouse gas” alongside the more long-lived but trace greenhouse gases). The strong amplification of the CO2 trigger is thought to be done by water vapour in certain key parts of the high atmosphere, a matter which Matt Ridley has ably highlighted and briefly outlined in a number of his recent lectures. So, as I understand it, the consensus climate science has it that carbon dioxide is not the “primary contributor” to the overall ongoing effect of global warming. As a recent example of the science, here’s Gavin Schmidt (now director of NASA GISS) in the 2010 peer-reviewed paper ‘Attribution of the present-day total greenhouse effect’

“With a straightforward scheme for allocating overlaps, we find that water vapor is the dominant contributor (~50% of the effect), followed by clouds (~25%) and then CO2 with ~20%.”

Which means that Pruitt is scientifically correct in what he said: C02 is not the… “primary contributor to the global warming that we see” today. According the man who is now the head of climate research at NASA, C02’s role in the overall process is “~20%”.

I imagine that Pruitt knows very well the scientific distinction between CO2 as ‘primary trigger’ and water vapour as ‘primary contributor’, but is banking that clueless newspaper and TV science journalists don’t — and that they will now make fools of themselves in their blind rush to hate on President Trump and his team. Also note that he carefully said “contributor”, not “controller”. Water vapour follows temperature, it can’t control it, as I’m sure he knows.

Matt Ridley’s autumn 2016 lecture at the Royal Society explains this aspect of how global warming happens better than I can, in the larger context, and with charts and more besides…

“the theory of dangerous climate change depends on a whole extra step in the argument, one that very few politicians and journalists seem even to know about — the supposed threefold amplification of carbon dioxide’s warming potential, principally by extra water vapour released into the atmosphere by a warming ocean, and accumulating at high altitudes.”


Update: For those who want the hard science, beautifully and clearly explained by the lead scientist on a major NASA mission to the upper troposphere, this NASA TC4 Project podcast is what you want: listen from 6.15 mins to 22.30 mins. The whole podcast is also well worth your time, and this illustration will greatly aid understanding…

Evidently it’s not just about the water vapour and what position it reaches in the high troposphere, but also the ice specks that form there from that vapour and then how fast they fall. Since… “the ice fall velocity (Vi) is the second most important factor affecting the climate sensitivity in GCMs [climate models].” (quote and picture from “Representing the Ice Fall Speed in Climate Models: Results from TC4, SPARTICUS and ISDAC”, 2011)

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