Barring complexities from gas mixing (we generally assume CO2 is a well mixed gas in the atmosphere), I’ve done some back of the napkin calculations, and come up with about a 3.8% maximum attribution to humanity.
That sounds like a pretty tricky approach to use. You have to know how CO2 emissions vary with the work week (people still use electricity, drive, etc. on weekends), you have to know how CO2 distributes through the atmosphere, and you have to be careful about how you choose the measuring station. Clearly one cannot use the readings in Mauna Loa Observatory, whose location was intentionally chosen to be far from civilization; I imagine it takes days or weeks for CO2 to distribute evenly throughout the atmosphere, and weather patterns will make the mixing uneven.
Of course, the difficulty in excluding all other possible explanations is that not all explanations are known — you could exclude, say, the breeding habits of northern voles from any global warming component, but you might not be able to anticipate that the breeding habits of phytoplankton have a significant effect on atmospheric CO2.
This idea is a lot like saying Bigfoot exists. The claim is
- far more easily evaluated by experts who have spent their lives studying CO2 sources, sinks, and chemistry, rather than either of us (and if you got the idea from Curry, note that her expertise is in hurricanes)
- a moot point. It is not a reason for us, as members of the general public, to say “let’s not act on climate change.” Thus there is no reason to feed this message to the public.
As for the temporal lag in the ice cores, sadly, the proxies aren’t high resolution enough to compare well to the modern instrumental era. Changes, such as observed over the past 150 years, are smoothed out in the ice core record, so it’s not a valid comparison.
Are you proposing that in the past CO2 massively and mysteriously increased over periods of 50 years and then, just as massively and just as mysteriously decreased, so fast that the jump is completely invisible in ice core records?
Since there’s no evidence or any reason to believe that, this is similar to a claim that all emeralds toggle between blue and green every million years. It’s an example of why we use Occam’s Razor.
What argument, contrary to your beliefs, is one that you have the hardest time refuting?
I have successfully refuted every argument I’ve seen, except your asking for a (1) falsifiable hypothesis and a (2) other thing that I didn’t understand, was pretty difficult for me. The tropospheric hot spot issue was difficult until I understood it better.