From Will:
"The majority of scientists who are studying climate are saying that humans have had an impact on climate, but they don't go saying it's the end of the world either. That's what journalists are for.
And many politicians, like Al Gore.
Unfortunately some people, like alarikf, seem to have bought into the alarmist scenarios (I doubt he'd be "physically sickened" by climate skeptics unless he really believed in Doomsday). The current "climate" (ouch) of hysteria has already led to expensive "corrective" action not justified by the actual science.
"You cannot deny the entire hypothesis that human action has increased global temperatures based solely on a few bits of data that does not fit the model."
I'm
skeptical of the hypothesis because
a lot of data don't fit the model.
"We have very accurate data from late 1800's to present for temperature..."
We
don't. As I pointed out in an earlier post, even direct historical measurements are uncertain due to location, changes in location, lack of coverage (especially the oceans), changes in instrumentation, land use changes, etc. etc. Note also that satellite and balloon measurements show less warming than ground stations.
"...(to within fractions of a degree)."
We're confusing precision with accuracy here.
"We have fairly accurate data going back several centuries..."
See my earlier posts on climate proxies and the "hockey stick" debacle.
"It [ice cores] shows strong correlations between percentage of atmospheric carbon dioxide and temperature."
Correlation is not causation. And as Gozra pointed out, it's an open question whether carbon dioxide changes preceded or actually followed temperature shifts. (All this assumes, of course, that ancient ice bubbles are as pristine as paleoclimatologists like to believe -- more uncertainty.)
But who knows? Maybe one day the ice drillers will find one of those Viking SUVs that caused the Medieval Warm Period!