As far as # 2 goes, ice core data is used for
recent paleoclimate data on CO2 concentration, nothing much earlier than about 1000 years ago, because of the errors inherent in the ice core data.
The most recent major paper (Sherwood) indicates quite the opposite, and absolutely none of
the recent paleoclimate data indicates this, which is a big part of the data that we are looking at in detail to ascertain sensitivity.
Not exact matches
So if you could then bring all these together — parts per millions, the global forcing and sea - level rise — based on the
paleoclimate record, which is, kind of, the really more a
recent data that the new view is built on.
However, values this low are inconsistent with numerous studies using a wide variety of methods, including (i)
paleoclimate data, (ii)
recent empirical
data, and (iii) generally accepted climate models.
That is the case whether you are extrapolating from
paleoclimate data or from any
recent temperature dataset vs atmospheric CO2 concentration measurements (eg Keeling curve).
Methods have improved of course, and no doubt will improve further (
paleoclimate reconstruction using weather forecast
data assimilation methods is the latest and most promising
recent development).
That is the case whether you are extrapolating from
paleoclimate data or from any
recent temperature dataset vs atmospheric CO2 concentration measurements (eg Keeling curve).
«In reality climate models have been tested on multicentennial time scales against
paleoclimate data (see the most
recent PMIP intercomparisons) and do reasonably well at simulating small Holocene climate variations, and even glacial - interglacial transitions.
Anyone who would like to discuss with me the facts revealed by the Wegman report that there is a
paleoclimate mafia controlling what gets published, that they have systematically published erroneous interpretations of paleoclimatic
data, and that almost any paleoclimatic temperature profile can be obtained depending on how you manipulate the proxies, just email me at drdrapp [at] earthlink.net and tell me your name, address, professional affiliation, and
recent work you have done climate science.
Hansen and Sato (2012), using
paleoclimate data rather than models of
recent and expected climate change, warn that «goals of limiting human made warming to 2 °C and CO2 to 450 ppm are prescriptions for disaster» because significant tipping points — where significant elements of the climate system move from one discrete state to another — will be crossed.
Authors of a
recent study published in Science Advances used
paleoclimate data to examine how rainfall patterns have responded to past climate shifts.