I really don't know if we need another thread like this, but earlier discussions of paleoT have been scattered about. Mainly I wanted to mention another new one by Mulvaney et al in Nature (journal) “Recent Antarctic Peninsula warming relative to Holocene climate and ice-shelf history” doi:10.1038/nature11391 Briefly, they examined another high-resolution ice core, stable isotope temperature proxies; all the ususal stuff. They found that temperatures were as high or higher than current during several intervals in the last 11,000 years. That part is consistent with some Greenland studies that mojo has mentioned recently, and by the way I'd still like to know the original journal citations for those. Because of the high resolution, they also assert that the last 100 years of temperature change is in the top 0.3% during the most recent 1500 years. The more you look, the more you see. I am still trying to assemble all this in my own mind, along with the complacent sea level during the last few 1000's years, and the recent (possibly) unprecedend reductions in non-polar glaciers. Including my favorite, Otzi the iceman, who recently melted out after about 4400 years in the freezer. Recent millenial climates are probably not as simple as "nothing like the current warming has happened since the pleistocene glaciers melted". The ups may or may not have been global, and if the 'isotope thermometers' do not have a really hard lock on air temperature, it will limit their utility. FWIW, I really doubt that we will understand paleoT well without figuring out how, when and where the ocean returns heat to the atmosphere. It is the elephant in the room, if not the Seismosaurus! All eyes on IPCC AR5 They are obliged to neither overstate nor understate 'the case' and it looks to me that these things have become more 'subtle' since AR4. None of this contrasts the energy trapping of CO2, the instrumental temperature records, or the several independent lines of evidence for recent ecological and other earth-system changes. You knew I had to toss that in Finally another new one Glacial thinning has sharply accelerated at major South American icefields
This reminded me of an early Star Trek episode where an advanced race discovered a survivor in a crashed ship. Not having seen the injured woman or any records of our species, they applied their medical skills and the survivor lived . . . but horribly deformed. In one respect, trying to construct a paleo-thermometer looks like finding fragments of a glass tube thermometer, trying to rebuild it and reconstruct its record. Early in my career I had a similar challenge, reading crash-dumps and appreciate the difficulties. Bob Wilson
