Im November 2016 hielt Sebastian Lüning im Rahmen der Berliner EIKE-Klimatagung einen Vortrag zur Klimawirkung von Vulkanen. Eine Kurzbeschreibung erschien hierzu auf der EIKE-Webseite:
Dr. habil. Sebastian Lüning, Co Autor des Klimabestsellers „Die kalte Sonne“ berichtet über Vulkane, und ob deren zu unvorhersehbaren Zeiten erfolgenden Ausbrüche als „schwarze Schwäne des Klimageschehens gedeutet werden können. Der Ko-Autor des Klimabestsellers „Die kalte Sonne“ fängt damit an, dass er nun schon zum dritten Mal in Berlin zum Klimathema vorträgt. Das erste Mal, bei der Vorstellung des Buches „Die kalte Sonne“, dessen Thesen vom überaus starken Einfluss der Sonne über die verschiedensten Prozesse – insbesondere denen der atlantischen wie pazifischen Strömungen- sich seit dieser Zeit immer stärker bestätigt, über die Verabschiedung eines verdienten Geologie-Professors an der TU in den Ruhestand, bei dem Lüning zusammen mit den damaligen Vizechef des PIK F.W. Gerstengarbe, ein Streitgespräch führen durfte bis zum heutigen Tage.
Zur Einstimmung in das Thema zitiert er aus Nicolas Talebs berühmten Buch „Der schwarze Schwan“, um zu erläutern, dass damit unvorhergesehene, aber nicht ganz unwahrscheinliche, jedoch sehr wirkmächtige Ereignisse gemeint sind, die sämtliche Wahrscheinlichkeitsberechnungen, die fast alle auf irgendeine Weise mittels Gleichverteilungen und/oder Trendfortschreibungen bestimmt werden, über den Haufen werfen. Vulkane bzw. deren Ausbrüche gehören zweifelsfrei zu solchen Ereignissen. Z.B. in dem sie dank ihres Ascheauswurfes evtl. eine neuen kleine Eiszeit auslösen können.
Diese Hypothese verfolgten einige Autoren, die auch in „Nature “ veröffentlichen durften. Ziel war die ganze kleine Eiszeit als nicht sonnenabhängig zu erklären. Sie mussten aber später einräumen, dass sie sich schlicht im Zeitmaßstab vermessen hatten. Über dieses Eingeständnis, eines durchaus normalen Fehlers, wurde jedoch später von den Medien nicht mehr berichtet. Null. Spätere papers zeigten hingegen das ganze Gegenteil. Die klimatischen Einflüsse der Vulkane sind vorhanden (Sigi et. al 2015) aber nur sehr kurzfristig -in Klima relevanten Zeitmaßstäben- abkühlend wirksam. Später im Vortrag zeigt Lüning auf, dass auch Alfred Wegener einen solchen schwarzen Schwan – nämlich die Kontinentalverschiebung – entdeckt hatte. Die Sonnenaktivität hat, wie Lüning zeigt, einen ganz wesentlichen Anteil an der Erwärmung, weil bei jeder dieser massiven Erwärmungen, diese einen Höchststand hatte. Jedoch spielen sie im IPCC Bericht keinerlei Rolle.
Im Folgenden der Vortrag auf Youtube in voller Länge:
Dr. habil Sebastian Lüning, Bild EIKE
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Bleiben wir beim Thema Vulkane. Im Dezember 2016 erschien in Geology eine Arbeit von Kees Nooren und Kollegen, in der die Autoren einer Klima-Abkühlung um 540 n.Chr. nachgingen, zu der bisher der schuldige Vulkan fehlte. Nun ist der Ausbruch wohl lokalisiert. Es soll sich um den El Chichon in Mexiko handeln, wie Alterdatierungen an dessen Ablagerungen nun anzeigen. Abstract:
Explosive eruption of El Chichón volcano (Mexico) disrupted 6th century Maya civilization and contributed to global cooling
A remarkably long period of Northern Hemispheric cooling in the 6th century CE, which disrupted human societies across large parts of the globe, has been attributed to volcanic forcing of climate. A major tropical eruption in 540 CE is thought to have played a key role, but there is no consensus about the source volcano to date. Here, we present evidence for El Chichón in southern Mexico as the most likely candidate, based on a refined reconstruction of the volcano’s eruption history. A new chronological framework, derived from distal tephra deposits and the world’s largest Holocene beach ridge plain along the Gulf of Mexico, enabled us to positively link a major explosive event to a prominent volcanic sulfur spike in bipolar ice core records, dated at 540 CE. We speculate that voluminous tephra fall from the eruption had a severe environmental impact on Maya societies, leading to temporary cultural decline, site abandonment, and migration within the core area of Maya civilization.
Eine andere Forscherguppe hat sich mit den klimatischen Auswirkungen des Tambora-Ausbruchs 1815 und seine Auswirkungen auf Neuengland beschäftigt. Die University of Massachusetts at Amherst gab am 19. Januar 2017 die folgende Pressemitteilung hierzu heraus:
New England’s 1816 ‘Mackerel Year’ and Climate Change Today
UMass Amherst, New England researchers explore past global climate catastrophe
Hundreds of articles have been written about the largest volcanic eruption in recorded history, at Indonesia’s Mount Tambora just over 200 years ago. But for a small group of New England-based researchers, one more Tambora story needed to be told, one related to its catastrophic effects in the Gulf of Maine that may carry lessons for intertwined human-natural systems facing climate change around the world today.In the latest issue of Science Advances, first author and research fellow Karen Alexander at the University of Massachusetts Amherst and 11 others including aquatic ecologists, climate scientists and environmental historians recount their many-layered, multidisciplinary investigation into the effects of Tambora on coastal fish and commercial fisheries.
Alexander says, “We approached our study as a forensic examination. We knew that Tambora’s extreme cold had afflicted New England, Europe, China and other places for as long as 17 months. But no one we knew of had investigated coastal ecosystems and fisheries. So, we looked for evidence close to home.” In work that integrates the social and natural sciences, they used historical fish export data, weather readings, dam construction and town growth chronologies and other sources to discover Tambora’s effects on the Gulf of Maine’s complex human and natural system.
The 1815 eruption caused a long-lasting, extreme climate event in 1816 known as the “year without a summer.” As volcanic winter settled on much of the Northern Hemisphere, crops failed, livestock died and famine swept over many lands. In New England, crop yields may have fallen by 90 percent. The researchers found that 1816 was also called “the mackerel year,” a clue to what they would find regarding fisheries.
Besides Tambora’s climate effects, the authors examined other system-wide influences to explain observed trends. These included historical events such as the War of 1812, human population growth, fish habitat obstruction due to dam building and changes in fishing gear that might have affected fisheries at the time. Employing historical methods in a Complex Adaptive Systems approach allowed them to group and order data at different scales of organization and to identify statistically significant processes that corresponded to known outcomes, Alexander says.
For instance, temperature fluctuations influenced the entire Gulf of Maine for short periods of time, while dam construction affected individual watersheds through the life of the dams. Space and time scales differ in each case, but both temperature fluctuations and habitat obstructions affect fish, and thus fisheries, at the same time. Such interactions are characteristic of complex systems, she notes.
Establishing timing was key to solving the mystery, Alexander adds. Major export species including freshwater-spawning alewives and shad and marine-spawning mackerel and herring, have different temperature tolerances and seasonal migration patterns and timing, or phenology. Alewives and mackerel arrived earlier when water was colder, shad and herring arrive later after water had warmed up. Because of their phenology and vulnerability in rivers and streams during spawning, alewives suffered the most from the extreme climate event. In Massachusetts where streams had been dammed for a long time, its effects were compounded, the researchers found.
In the early 1800s alewives were a “utility fish,” an important commercial export but also used as chicken feed, garden fertilizer and human food in winter. The winter of 1816 was so cold, Alexander says, that “Penobscot Bay froze solid from Belfast to Castine.” When alewives arrived at their seasonal spawning time, adverse conditions likely disrupted spawning runs, increased natural mortality and, critically for the people depending on them, decreased catch.
She adds, “During this climate crisis, people couldn’t catch enough alewives to meet their needs, so they quickly turned to mackerel, the next abundant species to arrive along the coast. Pursuing mackerel and rapidly distributing it to communities with no other sources of food fundamentally altered the infrastructure of coastal fisheries.” Although records suggest that alewife populations apparently recovered within 25 years, “people responded rapidly and effectively to Tambora in only five years and never looked back when the crisis passed.”
Rates of human and alewife response became uncoupled and the quick fixes, become permanent, later achieved an air of inevitability, the authors suggest.
They add that “complex solutions elude simple explanations.” They point out the “many and obvious,” parallels between that sudden extreme event and current occurrences of drought, flood, storm devastation, food disruption and famine attributed to climate change.
“The past can be a laboratory,” Alexander and colleagues write. Employing historical methods within a Complex Adaptive Systems approach may offer a simple way to examine complex systems where scale, rate and phenology interconnect human and natural processes, andhelp to“advance human resilience by strengthening resilience in the natural world.”
UMass Amherst fisheries ecologist Adrian Jordaan adds, “When the resources are available locally, they can help societies cope with change. Also, during extreme climate events, unthinkable changes including large societal shifts can occur. These are things that we must be prepared for in the world of today, where extreme climatic events are becoming more frequent and severe.”
Michelle Staudinger, an ecologist with the Northeast Climate Science Center at UMass Amherst, says, “Alewives and other fishes that inhabit both rivers and oceans are highly vulnerable to climate change. The lessons learned from this study will help us better anticipate, prepare and cope for additional future impacts on their populations as well as the human communities that depend on them.”
Alex Bryan, a U.S. Geological Survey climate scientist and co-author, says studying a 200-year-old event was a challenge. “Long-term temperature records don’t begin until the turn of the 20th century. Fortunately, we found the weather journal of a physician residing in Salem, Mass., who recorded the air temperature four times a day from the 1780s to the 1820s. Without his devotion to monitoring the weather, this study would not have been possible.”
