GeoffBeacon,
While I personally do find many of Wasdell's point compelling, I must also agree with Richard Rathbone that Wasdell's methodology for the timescale of the feedback mechanisms is not robust enough to convince policy makers of the seriousness of this issue. Unfortunately, one would need a Global Circulation Model, that is more sophisticated than those currently available to prove Wasdell's points. For the past nominally 15 to 17 years the Earth's true climate sensitivity has been masked by such factors as: (a) the cool phases of both the PDO and the AMO; (b) heavy air pollution over much of Asia and Africa; (c) volcanic activity and (d) a temporary surge of plant growth in previously marginal regions (desert, and permafrost, areas). Now that such masking factors are coming to an end, we are likely to see abrupt warming for several decades as occurred in both the Younger, and Oldest, Dryers as cited in the following reference (see also the attached image from Buizert (2014)):
Christo Buizert, Vasileios Gkinis, Jeffrey P. Severinghaus, Feng He, Benoit S. Lecavalier, Philippe Kindler, Markus Leuenberger, Anders E. Carlson, Bo Vinther, Valérie Masson-Delmotte, James W. C. White, Zhengyu Liu, Bette Otto-Bliesner, & Edward J. Brook, (2014), "Greenland temperature response to climate forcing during the last deglaciation", Science, 5 September 2014: Vol. 345 no. 6201 pp. 1177-1180, DOI: 10.1126/science.1254961
http://www.sciencemag.org/content/345/6201/1177Abstract: "Greenland ice core water isotopic composition (δ18O) provides detailed evidence for abrupt climate changes but is by itself insufficient for quantitative reconstruction of past temperatures and their spatial patterns. We investigate Greenland temperature evolution during the last deglaciation using independent reconstructions from three ice cores and simulations with a coupled ocean-atmosphere climate model. Contrary to the traditional δ18O interpretation, the Younger Dryas period was 4.5° ± 2°C warmer than the Oldest Dryas, due to increased carbon dioxide forcing and summer insolation. The magnitude of abrupt temperature changes is larger in central Greenland (9° to 14°C) than in the northwest (5° to 9°C), fingerprinting a North Atlantic origin. Simulated changes in temperature seasonality closely track changes in the Atlantic overturning strength and support the hypothesis that abrupt climate change is mostly a winter phenomenon."
See also the following extract from:
http://www.sciencedaily.com/releases/2014/09/140904141953.htmExtract: "In addition to the gradual warming of five degrees (C) over a 6,000-year period beginning 18,000 years ago the study investigated two periods of abrupt warming and one period of abrupt cooling documented in the new ice cores. The researchers say their leading hypothesis is that all three episodes are tied to changes in the Atlantic meridional overturning circulation (AMOC), which brings warm water from the tropics into the high northern latitudes.
The first episode caused a jump in Greenland's air temperatures of 10-15 degrees (C) in just a few decades beginning about 14,700 years ago. An apparent shutdown of the AMOC about 12,800 years ago caused an abrupt cooling of some 5-9 degrees (C), also over a matter of decades.
When the AMOC was reinvigorated again about 11,600 years ago, it caused a jump in temperatures of 8-, 11 degrees (C), which heralded the end of the ice age and the beginning of the climatically warm and stable Holocene period, which allowed human civilization to develop.
"For these extremely abrupt transitions, our data show a clear fingerprint of AMOC variations, which had not yet been established in the ice core studies," noted Buizert, who is in OSU's College of Earth, Ocean, and Atmospheric Sciences. "Other evidence for AMOC changes exists in the marine sediment record and our work confirms those findings.""
Best,
ASLR