|Reconstructed mean summer SSA temperatures. Adapted from Neukom et al. (2011).|
- the Medieval Warm Period was a global phenomenon that was comprised of even warmer intervals than the warmest portion of the Current Warm Period, and that
- the greater warmth of the Medieval Warm Period occurred when there was far less CO2 in the air than there is nowadays, which facts clearly demonstrate that the planet's current -- but not unprecedented -- degree of warmth need not be CO2-induced.
Neukom, R., Luterbacher, J., Villalba, R., Kuttel, M., Frank, D., Jones, P.D., Grosjean, M., Wanner, H., Aravena, J.-C., Black, D.E., Christie, D.A., D'Arrigo, R., Lara, A., Morales, M., Soliz-Gamboa, C., Srur, A., Urritia, R. and von Gunten, L. 2011. Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries. Climate Dynamics 37: 35-51.
In order to know how unusual, unprecedented or unnatural the global warming of the 20th century was, it is necessary to do what the eighteen authors of this important paper did, so as to be able, as they describe it, "to put the recent warming into a larger temporal and spatial context."
Working with 22 of the best climate proxies they could find that stretched far enough back in time, Neukom et al. (2011) reconstructed a mean austral summer (December-February) temperature history for the period AD 900-1995 for the terrestrial area of the planet located between 20°S and 55°S and between 30°W and 80°W -- a region they call Southern South America (SSA) -- noting that their results "represent the first seasonal sub-continental-scale climate field reconstructions of the Southern Hemisphere going so far back in time."
Read more HERE.