That debate between AL and Dave kept on going, though it might be winding down now. I skipped some earlier posts by Dave to focus on his most recent remarks, then decided I'd better start with AL's typical contrarian assault, then I'll follow up with Dave's response in my next post.
A reminder - this comes from the comments thread begun by MarathonS Feb 22, 2014 on the dubious YouTube video The PseudoScience of CO2 Based Climate where yet another coddled "old white guy" who knows nothing of climate science, feeds his audience what they want to hear.
Note - Dave and AL's words are unchanged, though I have corrected some minor typos - I figured AL knows it all already, so I didn't touch his words. I also made formatting changes including some highlights and of course I've also interjected a few comments and more links to educational sources.
It's difficult keeping the participants in this virtual dialogue separate, please bear with me - Dave's words are in Arial font, AL's comments are in purple, my additions are light green highlighted.
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AL - 12/10/2015 -11:53 AM to Dave Smith
So to answer it - there isn't one (optimal CO2 level).
Of course there is. Every ecosystem has an optimal level for that particular ecosystem, just because you don’t know what that level is doesn’t mean there isn’t one. But since you now have admitted that you don’t know what that level is, why are you then promoting a certain level of CO2 when you lack that knowledge?
You quoted me a paper that stated that they are unprecented - Ljungqvist, F. C., et al. "Northern Hemisphere temperature patterns in the last 12 centuries." Climate of the Past 8.1 (2012): 227-249. How can you use references the state one thing and then claim as fact the opposite?
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Hmmm, tough to figure out what AL is talking about.
Here's a couple lines from the abstract:
"... The positive Northern Hemisphere temperature change from the 19th to the 20th century is clearly the largest between any two consecutive centuries in the past 12 centuries. These results remain robust even after removing a significant number of proxies in various tests of robustness showing that the choice of proxies has no particular influence on the overall conclusions of this study."
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What part of the climate has always been changing have you missed? Is it so impossible for you to grasp that there has always been changes in climate, and it always will. Since much larger changes has occurred in the past several times, even in the recent past, there is absolutely nothing unusual about a 0,5 - 1 C° temperature rise in over 120 years. Nor are the drop in temperature from for example MWP to LIA. Are you really that uninformed so you believe the climate you happened to have experienced in your lifetime is some kind of norm for our planet?
