Thursday, September 26, 2013

Little Ice Age was due to low solar activity, not high volcanic activity

Those who which to dismiss the role of the Sun in climate often claim the Little Ice Age was due to high volcanic activity rather than low solar activity. However, a new paper reconstructing the paleoclimate of Ireland over the past 5000 years shows that volcanic activity during the Little Ice Age was low in comparison to the Current, Medieval, and Roman Warm Periods, as well as most of the past 5,000 years. Based upon this reconstruction of volcanic sulphate from the Greenland GISP2 ice core, volcanic activity appears to show little correlation with long-term warming and cooling periods. 

In contrast, solar activity drops to the lowest levels of the past 5,000 years during the Little Ice Age and the Dark Ages Cold Period, and rises to relatively high levels during the Current, Medieval, and Roman Warm Periods. I'll leave it to the reader to decide which of the three primary drivers best explain climate variation of the past 5,000 years: volcanic, CO2, or solar.

Horizontal axis is years before the present [BP]. Current Warm Period [CWP] shown at left, Little Ice Age during next band in blue to the right, preceded by the Medieval Warm Period beginning about 1050 years ago. Next in blue is the Dark Ages Cold Period, preceded by the Roman Warm Period ~2000 years ago.
Portion of Fig 11: Climate forcing parameters include volcanic sulphate data from the GISP2 [Greenland] ice core (Zielinkski and Mershon, 1997), a combined CO
2 record from Mauna Loa, the Law Dome and EPICA Dome C ice cores (Keeling et al., 1976; Etheridge et al., 1996; Monin et al., 2004) and total solar irradiance data for the last 5,000 years (Steinhilber et al., 2004). Known climate events are marked (wetter/colder = blue; drier/warmer = red).


  1. Old News.

    See here: