From the comments, jfs says:
I think the global warming nonsense the commenter is refering to is not that fact that temperatures are increasing, which is what you cite in your links, but that the increase is not part of some natural climatic cycle….
The commenter raises a great question. Given the relatively short time we’ve had thermometers and recorded data, how can we make such bold assertions about the effect industrial greenhouse gas emissions might be having on climate?
For starters, I don’t think we should be making bold assertions, and I’m always pretty careful about how I phrase what we know and don’t know here. This is tough science. But there are some good answers to the question jfs raises. I’ll be brief and point you to more authoritative resources than some schmoe’s blog for the details and data.
The first is that climate proxies (tree rings, corals, etc.) have been used to extend the climate record back well before the era of thermometers and rain gauges. Those proxies suggest the current warming is unprecedented over considerably longer time scales than the 140 years jfs mentioned:
(That’s Mann, Science, Vol 297, Issue 5586, 1481-1482 , 30 August 2002)
Second, the greenhouse warming hypothesis makes some predictions about the details of the warming, and how one might distinguish anthropogenic greenhouse warming from other types of natural variability. Among the indicators studied are the day/night diurnal temperature range (more warming in the overnight temperatures than during the day because of radiative heat trapping), differences between temperatures over ocean vs. over land, etc. When they look for those differences, they find them. (Karoly et al., Science, Vol 302, Issue 5648, 1200-1203 , 14 November 2003 – that’s one of the links I offered, which perhaps jfs might want to give a second read)
Attempts to account for the amount and patterns of warming seen using other hypotheses – urban heat island effect, solar variability, etc. – have all come up short. (Chapter 12 of the most recent IPCC report has a lengthy discussion of all this. Web site directly to the chapter seems to be down today. Try back tomorrow?)
That’s not QED, but it’s pretty clearly the state of the science right now – the anthropogenic hypothesis is the best fit to the facts as we know them.
And yeah, Jimbob, you’re right. I didn’t say anything about what was causing it in the beetle post.