Das PIK und die nachlassende Wirkung des Zaubertranks

Sonnenmobbing im Nature-Ableger Scientific Reports. Ein Autorenkonsortium um D. A. Smirnov unter Beteiligung von gleich drei PIK-Leuten versucht das Klima der Vergangenheit mit Vulkanausbrüchen zu erklären. Der Sonne traut man nichts zu, denn wenn sie in der Vergangenheit das Klima kontrolliert hätte, müsste man ihr ja auch in der heutigen Zeit eine Wirkung zubilligen. So ganz konnte man die Vulkane dann aber doch nicht hinbiegen. Im Bereich der Mittelalterlichen Wärmeperiode rechnet man plötzlich mit einem spürbaren solaren Wärmeeffekt. Um das CO2 in seiner Wirkung nicht zu schwächen, greift man dann zu einem putzigen Trick: Man erklärt einfach einen “Regime-Wechsel”. Irgendwann zwischen 1000-1300 n.Chr. soll die Sonne ihre Klimapower verloren haben, so wie Asterix bei dem die Wirkung des Zaubertranks nachlässt. Ohne Worte. Abstract:

A regime shift in the Sun-Climate connection with the end of the Medieval Climate Anomaly
Understanding the influence of changes in solar activity on Earth’s climate and distinguishing it from other forcings, such as volcanic activity, remains a major challenge for palaeoclimatology. This problem is best approached by investigating how these variables influenced past climate conditions as recorded in high precision paleoclimate archives. In particular, determining if the climate system response to these forcings changes through time is critical. Here we use the Wiener-Granger causality approach along with well-established cross-correlation analysis to investigate the causal relationship between solar activity, volcanic forcing, and climate as reflected in well-established Intertropical Convergence Zone (ITCZ) rainfall proxy records from Yok Balum Cave, southern Belize. Our analysis reveals a consistent influence of volcanic activity on regional Central American climate over the last two millennia. However, the coupling between solar variability and local climate varied with time, with a regime shift around 1000–1300 CE after which the solar-climate coupling weakened considerably.

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Eos am 13. Oktober 2017 mit der Antwort auf eine wichtige Grundsatzfrage:

Is There a Greenhouse Effect in the Ionosphere, Too? Likely Not
Controversial observations of long-term changes in the ionosphere appear to be explained by the Sun’s 11-year cycle of activity, not human greenhouse gas emissions.

In the late 1980s, climate scientists began raising concerns that human emissions of greenhouse gases were warming Earth’s climate. At the time, some space physicists also predicted that such emissions could alter the ionosphere, the high-altitude layers of the atmosphere that consist of charged particles, ionized by the Sun or captured from space. In the intervening years the consensus that human carbon emissions are altering Earth’s climate has only solidified. But in the case of the “ionospheric greenhouse effect,” the jury is still out, with decades of mixed results that include some observational evidence. But now a new study by Mikhailov et al. makes a strong argument that most of these variations are not due to human activity but to solar activity. The ionosphere, they found, is just responding to the Sun’s 11-year cycle, in which its magnetic field slowly wraps itself into knots and produces periods of intense sunspots and flares.

Weiterlesen auf Eos.

Kein Treibhauseffekt in der Ionosphäre, sondern Steuerung durch die solare Aktivität. Gut zu wissen. Aber die Überaschung hält sich in Grenzen.