Igor, are you responding to my post?
On Jan 30, 10:24 am, Igor Samoylenko <[email protected]> wrote:
> It is not just Younger Dryas but also numerous other abrupt climate jumps
> during the last Ice Age cycle known as Dansgaard-Oeschger and Heinrich events
> are all thought to be linked to fresh-water fluxes and resulting disruption
> of North Atlantic deep water formation. There is a lot of literature on this
> topic, but here is a good summary paper:
>
> Alley, R.B. Wally Was Right: Predictive Ability of the North Atlantic
> “Conveyor Belt” Hypothesis for Abrupt Climate Change. Earth and Planetary
> Sciences35, 241-272 (2007).
> http://shadow.eas.gatech.edu/~kcobb/abrupt/alley07.pdf.
>
> "Linked, abrupt changes of North Atlantic deep water formation, North
> Atlantic sea ice extent, and widespread climate occurred repeatedly during
> the last ice age cycle and beyond in response to
> changing freshwater fluxes and perhaps other causes. This paradigm, developed
> and championed especially byW.S. Broecker, has repeatedly proven to be
> successfully predictive as well as explanatory with
> high confidence. Much work remains to fully understand what happened and to
> assess possible implications for the future, but the foundations for this
> work are remarkably solid."
>
> Chris Turney has a whole chapter on this in his book Ice, Mud and Blood
> Lessons from the climate past.
>
> As forTsonisandSwanson, you are of course aware of their recent paper:
>
> Swanson, K.L., Sugihara, G. &Tsonis, A.A. Long-term natural variability and
> 20th century climate change. Proceedings of the National Academy of
> Sciences106, 16120-16123 (2009).
> http://www.pnas.org/content/106/38/16120.abstract
>
> "Global mean temperature at the Earth's surface responds both to
> externally imposed forcings, such as those arising from anthropogenic
> greenhouse gases, as well as to natural modes of variability internal
> to the climate system. Variability associated with these latter
> processes, generally referred to as natural long-term climate
> variability, arises primarily from changes in oceanic circulation. Here
> we present a technique that objectively identifies the component of
> inter-decadal global mean surface temperature attributable to natural
> long-term climate variability. Removal of that hidden variability from
> the actual observed global mean surface temperature record delineates
> the externally forced climate signal, which is monotonic, accelerating
> warming during the 20th century."
>
> So, do you accept that (having removed natural variability) we have
> externally forced climate signal, which is monotonic, accelerating warming
> during the 20th century?
I haven't read the paper in the PNAS by Kyle Swanson, et al., as it's
behind a pay wall. But, from the information I've seen, it sure looks
like the Earth is experiencing a warming trend. I can't speak for
Robert...
E. S.
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