Konfliktforschung 1400-1900: Je kälter das Klima, umso häufiger rasselten die Völker aneinander

Im Januar 2017 erschien das NBER Working Paper einer Forschergruppe um Murat Iyigun, in dem die Geschichte militärischer Konflikte zwischen 1400 und 1900 ausgewertet wird. Das unerwartete Resultat: Je kälter das Klima, umso häufiger rasselten die Völker aneinander. Hier der Abstract:

Winter is Coming: The Long-Run Effects of Climate Change on Conflict, 1400-1900
We investigate the long-run effects of cooling on conflict. We construct a geo-referenced and digitized database of conflicts in Europe, North Africa, and the Near East from 1400-1900, which we merge with historical temperature data. We show that cooling is associated with increased conflict. When we allow the effects of cooling over a fifty-year period to depend on the extent of cooling during the preceding period, the effect of cooling on conflict is larger in locations that experienced earlier cooling. We interpret this as evidence that the adverse effects of climate change intensify with its duration.

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Spiegel Online wagte es am 20. Januar 2017 gegen den politischen Mainstream zu schwimmen und brachte eine Öko-Story, bei der der Klimawandel doch tatsächlich einmal unbeteiligt ist und freigesprochen wird:

Steinzeitliches Massensterben Mensch, du warst der Killer!
Weltweit starben die Riesen unter den Tieren vor Zehntausenden Jahren aus. War es ein Klimawandel oder war es der Mensch? Forscher glauben nun, das klar beantworten zu können – und fällen einen Schuldspruch.

Ein australisch-amerikanisch-deutsches Forscherteam um den Paläontologen Sander van der Kaars glaubt, stichhaltige Indizien gefunden zu haben, die eine uralte Streitfrage beantworten sollen: Was war schuld am zu unseren Tagen letzten Massensterben der Megafauna – Mensch oder Klimawandel? Kaars und Kollegen zeigen mit einer in den “Nature Communications” veröffentlichten Studie über das Verschwinden der australischen Megafauna, dass ein Klimawandel nichts mit diesem Massensterben zu tun hatte – der Mensch verursachte das offenbar aus eigener Kraft.

Weiterlesen auf Spiegel Online

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Schon gewusst? Während des letzten Interglazials – also der Warmzeit zwischen den letzten beiden Eiszeiten – war es ähnlich warm wie heute. Dies rief die American Association for the Advancement of Science am 19. Januar 2017 per Pressemitteilung in Erinnerung:

Sea-surface temps during last interglacial period like modern temps

Sea-surface temperatures during the last interglaciation period were like those of today, a new study reports. The trend is worrisome, as sea levels during the last interglacial period were between six and nine meters above their present height. The last interglaciation (LIG), which occurred 129,000 to 116,000 years ago, is thought to have been about as warm or a bit warmer than today, making it a useful reference to validate global climate models and understand sea-level response to a warming climate.

Here, Jeremy S. Hoffman and colleagues compiled 104 published LIG sea surface temperature (SST) records from 83 marine sediment core sites. They compared each core site to data sets from 1870-1889 and 1995-2014, respectively. Their analysis reveals that, at the onset of the LIG 129,000 years ago, the global ocean SST was already similar to the 1870-1889 average.

However, by 125,000 years ago, the global SST increased by 0.5° ± 0.3°Celcius, reaching a temperature indistinguishable from the 1995-2014 average. These results suggest that LIG global mean annual SSTs simulated with most global climate models are too low. As well, the data show that the Atlantic Ocean in the Northern Hemisphere was cooler at the beginning of the LIG, compared to temperatures in the Southern Hemisphere. Collectively, these results may help scientists better understand how oceans will respond to modern warming.

Journal Reference: Jeremy S. Hoffman, Peter U. Clark, Andrew C. Parnell, Feng He. Regional and global sea-surface temperatures during the last interglaciation. Science, 2017; 355 (6322): 276 DOI: 10.1126/science.aai8464