New study shows solar minimum does cause climate cooling

A new paper in Nature Geoscience shows that solar grand minima do indeed cause cooling of the climate in Europe. Around 2800 years ago, one of these Grand Solar Minima, the Homeric Minimum, caused a distinct climatic change in less than a decade in Western Europe. The forcing mechanisms still remain unclear but the evidence that solar effects are significant and cannot be ignored are mounting and persuasive. Now as we enter (or have already entered) a new solar minimum it remains to be seen as to whether this (Landscheidt?) Minimum will be a grand minimum to compare with the Maunder Minimum. In any event a period of global cooling seems likely.

In contrast, the evidence for any anthropogenic effects on climate is still non-existent though political and alarmist theories abound. There is as yet no direct evidence that man-made carbon dioxide emissions has any significant effect on global warming.

Regional atmospheric circulation shifts induced by a grand solar minimum by Celia Martin-Puertas, Katja Matthes, Achim Brauer, Raimund Muscheler, Felicitas Hansen, Christof Petrick, Ala Aldahan, Göran Possnert & Bas van Geel

Nature Geoscience (2012) doi:10.1038/ngeo1460

Science Daily covers the paper:

An abrupt cooling in Europe together with an increase in humidity and particularly in windiness coincided with a sustained reduction in solar activity 2800 years ago. Scientists from the German Research Centre for Geosciences GFZ in collaboration with Swedish and Dutch colleagues provide evidence for a direct solar-climate linkage on centennial timescales. Using the most modern methodological approach, they analysed sediments from Lake Meerfelder Maar, a maar lake in the Eifel/Germany, to determine annual variations in climate proxies and solar activity.

The study published online this week in Nature Geoscience reports the climatic change that occurred at the beginning of the pre-Roman Iron Age and demonstrates that especially the so-called Grand Minima of solar activity can affect climate conditions in western Europe through changes in regional atmospheric circulation pattern. Around 2800 years ago, one of these Grand Solar Minima, the Homeric Minimum, caused a distinct climatic change in less than a decade in Western Europe.

The exceptional seasonally laminated sediments from the studied maar lake allow a precise dating even of short-term climate changes. The results show for a 200 year long period strongly increased springtime winds during a period of cool and wet climate in Europe. In combination with model studies they suggest a mechanism that can explain the relation between a weak sun and climate change. “The change and strengthening of the tropospheric wind systems likely is related to stratospheric processes which in turn are affected by the ultraviolet radiation” explains Achim Brauer (GFZ), the initiator of the study. “This complex chain of processes thus acts as a positive feedback mechanism that could explain why assumingly too small variations in solar activity have caused regional climate changes.” …

The Homeric Minimum was discussed by Landscheidt in a 1981 paper as one of the 5 grand minima since 1500 BC linked to climate change. His prediction then that “It is to be expected that the climatic conditions in at least three decades after 1990 will be more severe than after 1811…” now seems prescient:

Eddy has focused attention on the finding that the 14C-record bears the unmistakable signature of grand minima in solar activity. …….  there occurred only five such minima since 1500 BC. Following Eddy’s nomenclature these were the Maunder Minimum (M), the Spoerer Minimum (S), the Greek Minimum (G), the Homeric Minimum (H), and the Egyptian Minimum (E). …..

In the last millenium the world’s climate has undergone changes which correspond closely in date, phase, and amplitude with the sun’s long-term variations in question (Gates and Mintz, 1975). The Spoerer-Minimum and the Maunder Minimum match the so-called Little Ice Age (Eddy, 1977). Regarding this link, exact predictions in the sun’s secular cycle including quantitative evaluations constitute a valuable means of providing for the future as to power generation for instance. Characteristically, the last great advance of Alpine glaciers, though not as prolonged as during grand minima, occurred in the decades after 1810 (Rudloff, 1967). It is to be expected that the climatic conditions in at least three decades after 1990 will be more severe than after 1811 …….

Tags: climate change, Homeric Minimum, Landscheidt Minmum, Maunder Minimum, Pre-Roman Iron Age, solar effects on climate, Solar minimum, Solar variation