In the last post we looked at the recent temperature reconstruction for the holocene, in particular the last 11,300 years, from Marcott et al. We noted that the changes over most of this very long time span were no bigger, but a lot slower, than the changes over the last century or so. That means trouble.
We also mentioned that the “uptick” at the end of their “main” (the “Standard 5×5”) reconstruction was much larger than in their RegEM reconstruction, and that they had expressed doubt about its robustness. The large uptick at the end (in 1940) is larger than indicated by the instrumental data — another reason to doubt its reality. Let me tell you my opinion why this difference exists. I could be mistaken, but this is what I think.
There’s a new reconstruction of past temperature covering the last 11,300 years by Marcott et al. (2013, A Reconstruction of Regional and Global Temperature for the Past 11,300 Years, Science, Vol. 339 no. 6124 pp. 1198-1201, DOI:10.1126/science.1228026). Data for their reconstructions, and the proxy data on which they’re based, are part of the supplementary materials.
The Marcott reconstruction has been joined to the Shakun reconstruction prior to that, and the HadCRUT4 global temperature data since, and the projected temperature change under the A1B scenario for the future, by Jos Hagelaars, in order to show us some perspective on climate change past, present and future.
This graph has been dubbed the “wheelchair.” Compared to the past, what’s happening in the present is scary. The future is scary as hell.