Click following link for above paperSolar Forcing of Regional Climate Change During the Maunder Minimum
This is what they then said:
"These results provide evidence that relatively small solar forcing may play a significant role in century-scale NH winter climate change. This suggests that colder winter temperatures over the NH continents during portions of the 15th through the 17th centuries (sometimes called the Little Ice Age) and warmer temperatures during the 12th through 14th centuries (the putative Medieval Warm Period) may have been influenced by longterm solar variations."
The trouble is that instead of pursuing that approach they seem to have junked it after assuming that the same mechanisms were no longer in control during the late 20th century.
Furthermore they omitted certain additional components that with the passage of time are becoming more clearly self evident.
They made the following errors:
i) They did not realise that although the regional changes were most apparent those changes did in fact reflect a change in the global energy budget from net warming to net cooling or vice versa.
ii) They were probably thrown by the observation of a cooling stratosphere whilst the sun was more active when the established ideas would have expected a warming stratosphere from a more active sun. However they do seem to have realised that a warmer lower stratosphere near the poles was required for a more equatorward jetstream regime yet that happened when the sun was less active not more active. They should have looked into that in more detail. I think it is now becoming apparent that an active sun cools the stratosphere whereas a less active sun warms it. The data referred to recently by Joanna Haigh suggests that the sign for the solar effect on certain layers of the atmosphere needs to be reversed. That would resolve the apparent discrepancy in their 2001 paper.
iii) Athough they explicitly acknowledge the modulating bottom up effect of oceanic oscillations they do not follow through. They should have realised that top down high solar activity combined with bottom up positive oceanic influences would in combination be enough to produce the late 20th century warming without having to invoke a significant effect from more CO2.
iv) They even note the effect of cloud quantity changes but again do not follow through. Applying a little logic it must be the case that jetstreams waving around latitudinally will produce more clouds than jetstreams travelling in relatively straight lines around the globe.
v) They even acknowledge that energy input to the oceans is affected but fail to link it explicitly to cloudiness and global albedo changes.
vi) They further acknowledge the role of ozone and thereby impliedly accept that the solar effects are chemically and not radiatively driven.
vii) Their consideration of ozone effects does not consider the mesosphere and it is there that I think the main error arises for established climatology. It is the solar effect on the mesosphere that drives the reverse sign solar temperature effect for both mesosphere and stratosphere as I have explained elsewhere.
So, contrary to what many seem to think my proposals for a new climate description expressed here and elsewhere have a sound basis in the established findings of both Schmidt and Mann but I have gone several steps further in explaining why the real world is now diverging from the expectations that they derived from the incorrect assumption that man made CO2 had upset the natural order of things.