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Re: [Phys-L] just for fun?




I think I already addressed WHY this is a major talking point--namely how the historical data has been used (misused). I would also offer that the magnitude of the lag makes a clear cut feedback loop a little harder to pin down--again primarily for the non-scientist.

That the models and basic science predicts that if CO2 leads then temperature should follow is not being disputed (by me), but the approach taken by Gore in Inconvenient Truth--"look at my graph and it is obvious these graphs fit together (and by implication show that rising CO2 causes temperature rise) just like the continents fit together and if you don't accept both you're an idiot" triggered a rash of rebuttals (mostly as ill-informed as the original) but keeps this particular issue in play. [The bottom line is that looking at this point makes it look like Gore outright lied in his use of the historical data graphs which gives people a excuse for ignoring everything else he said. It doesn't matter if there is _some truth_ in the graphs if the mechanisms are complex and far from obvious especially in light of the tone in which they were presented. We need to keep in mind that for most of the population, if they know anything much about GW, it comes from An Inconvenient Truth and/or the Heartland Institute or YouTube offerings like The Great Global Warming Swindle. One year I showed both films and the class was pretty much divided (before we broke down the fact from fiction.)]

Back to an earlier point about wanting a more middle ground which JD criticized, on GW issues I would offer that the 'impending apocalypse' versus 'warming is good for us' dichotomy isn't very helpful--the former taking worst-case scenarios to extremes and treating them as 100% proven science and the latter completely ignoring the science. This is an issue that the IPCC has addressed by lowering their worst-case scenarios which were originally based on pretty extreme assumptions (like North Korea's economy surpassing the U.S by 2100). Sure the ultimate answer can be towards the extremes, but if you get most people to accept a middle position it is much easier to move that acceptance towards one end or the other versus trying to swing from one extreme to the other.

rwt


On 1/3/2014 11:20 PM, John Mallinckrodt wrote:
I've never understood this talking point. To first order rising temperatures lead to rising levels of CO2 and rising levels of CO2 lead to rising temperatures. As John Denker has already pointed out, it's a positive feedback loop.

Historically it's easy to imagine mechanisms that would increase the temperature and LEAD to increased levels of CO2 (thereby further increasing the temperature, thereby ... etc.). I've heard of the research suggesting the opposite, but frankly I can't help being a little skeptical. I'm not a climatologist, but on the basis of simple physical considerations I would EXPECT the historical record to show temperature leading CO2.

But in modern times, we know with very high confidence that CO2 in the atmosphere has been driven to levels unseen in at least hundreds of thousands of years and that the source of that increase is anthropogenic, NOT thermal. This is clearly the first time that such a thing has happened in the Earth's entire history. Furthermore, we know to expect higher temperatures to RESULT from these higher levels of CO2 and that is what we are seeing.

What am I missing?

John Mallinckrodt
Cal Poly Pomona
On Jan 3, 2014, at 7:16 PM, David Marx wrote:



--
Richard Tarara
Professor of Physics
Saint Mary's College

free Physics educational software
www.saintmarys.edu/~rtarara/software.html