Paper shows solar activity at end of 20th century was the highest in 1200 years

A paper published in Living Reviews of Solar Physics finds from 2 cosmogenic isotope proxies that solar activity at the end of the 20th century was at the highest levels of the past 1200 years. Many other papers also confirm that solar activity reached a Grand Solar Maximum at the end of the 20th century. However, according to the IPCC, this has nothing to do with 0.7C of global warming since the end of the Little Ice Age in 1850. 

 

Image from Wikipedia showing Beryllium 10 proxy

A History of Solar Activity over Millennia

Ilya G. Usoskin
Sodankyla Geophysical Observatory (Oulu unit)
University of Oulu, Finland

Abstract: Presented here is a review of present knowledge of the long-term behavior of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview of the special indices used to quantify different aspects of variable solar activity, with special emphasis upon sunspot number.

Over long timescales, quantitative information about past solar activity can only be obtained using a method based upon indirect proxy, such as the cosmogenic isotopes 14C and 10Be in natural stratified archives (e.g., tree rings or ice cores). We give an historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state. Special attention is paid to the verification and cross-calibration of reconstructions. It is argued that this method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to
millennia) during the Holocene.

A separate section is devoted to reconstructions of strong solar–energetic-particle (SEP) events in the past, that suggest that the present-day average SEP flux is broadly consistent with estimates on longer timescales, and that the occurrence of extra-strong events is unlikely. Finally, the main features of the long-term evolution of solar magnetic activity, including the statistics of grand minima and maxima occurrence, are summarized and their possible implications, especially for solar/stellar dynamo theory, are discussed.