What is magnetic dating used for
The correlation of temperature with sunspots is obviously better than that with CO2, at least until the rapid descent into the Eddy Minimum after 1995.
Of course there are other factors, including the CO2 greenhouse.
Solar activity is usually assumed for changes faster than the other two, but geomagnetic excursions can be rapid too.
It is quite worrying that the geomagnetic dipole seems to be collapsing just as quickly as it did in the Laschamp event.
As I noted in a reply to Donb, the bible on geomagnetic excursions is the chapter by C. The halflife of 10Be is 1.4 million years, so it provides useful data throughout the Quaternary (Pleistocene plus Holocene).
A few days later, retired Apollo astronaut Phil Chapman sent me this article which lays some of the doubts to rest.By looking at factory dated lighters we can make some assumptions that that the lighter was made either in that particular year or maybe the year before.All the information on this page has been obtained from a study of these dated lighters.The actual mechanism by which the quiet sun cools the climate (Svensmark nucleation of low clouds by GCRs, changes in the sunlight spectrum, etc.) is not however germane here. Channell in the massive Treatise on Geophysics published by Elsevier in 2007, which is available here.The important point is that the climate varies with solar activity, whatever the mechaism may be. According to these authors (and all the evidence they cite) “it is now firmly established that the strength of the geomagnetic field is the most important factor controlling cosmogenic radionuclide production.” As Javier pointed out, Fig 7 in Mc Kraken et al shows a very large spike in 10Be at the time of the Laschamp excursion.