Zitat von Zettel im Beitrag #21

---

Zitat von Erling Plaethe im Beitrag #18

---

Nee klar, wenn an unterschiedlichsten Messpunkten auf der Welt ein Anstieg gemessen wird und keine das Messergebnis verfälschenden Faktoren bestehen, dann ist es eben so, dass der CO2-Anteil in der Atmosphäre steigt.

---

Es wäre ja auch seltsam, wenn er nicht stiege, denn bei der Verbrennung fossiler Brennstoffe oxidiert nun einmal C zu CO2. Das ist einfach so. Es geht nur darum, wie stark dieser Sachverhalt sich auf den CO2-Gehalt der Atmosphäre auswirkt, und das ist eine schwierige Sache, weil CO2 ja auch von Pflanzen aufgenommen wird, beispielsweise; weil es, allgemein gesagt, "CO2-Senken" gibt.

---

Zitat von http://carbon-budget.geologist-1011.net

---

The estimation of worldwide volcanic CO2 emission is undermined by a severe shortage of data. To make matters worse, the reported output of any individual volcano is itself an estimate based on limited rather than complete measurement. One may reasonably assume that in each case, such estimates are based on a representative and statistically significant quantity of empirical measurements. Then we read statements, such as this one courtesy of the USGS (2010):

Scientists have calculated that volcanoes emit between about 130-230 million tonnes (145-255 million tons) of CO2 into the atmosphere every year (Gerlach, 1991). This estimate includes both subaerial and submarine volcanoes, about in equal amounts.

In point of fact, the total worldwide estimate of roughly 55 MtCpa is by one researcher, rather than "scientists" in general. More importantly, this estimate by Gerlach (1991) is based on emission measurements taken from only seven subaerial volcanoes and three hydrothermal vent sites. Yet the USGS glibly claims that Gerlach's estimate includes both subaerial and submarine volcanoes in roughly equal amounts. Given the more than 3 million volcanoes worldwide indicated by the work of Hillier & Watts (2007), one might be prone to wonder about the statistical significance of Gerlach's seven subaerial volcanoes and three hydrothermal vent sites. If the statement of the USGS concerning volcanic CO2 is any indication of the reliability of expert consensus, it would seem that verifiable facts are eminently more trustworthy than professional opinion.

This is not an isolated case. Kerrick (2001) takes a grand total of 19 subaerial volcanoes, which on p. 568 is described as only 10% of "more than 100 subaerial volcanoes". It is interesting to observe that Kerrick (2001) leaves out some of the more notable volcanoes (eg. Tambora, Krakatoa, Mauna Loa, Pinatubo, El Chichon, Katmai, Vesuvius, Agung, Toba, etc.). Nevertheless, despite these omissions Kerrick calculates 2.0-2.5 x 1012 mol of annual CO2 emissions from all subaerial volcanoes, which is understated on the assumption that the sample is from the most active volcanic demographic. This is in spite of the fact that eight of the world's ten most active volcanoes are omitted from Kerrick's study (Klyuchevskoy Karymsky, Shishaldin, Colima, Soufriere Hills, Pacaya, Santa Maria, Guagua Pichincha, & Mount Mayon). At 44.01g/mol, 2.0-2.5 x 1012 mol of CO2 amounts to a total of 24-30 MtCpa - less than 0.05% of total industrial emissions (7.8 GtCpa according to IPCC, 2007). My main criticism of Kerrick's guess is that it putatively covers only 10% of a highly variable phenomenon on land, and with the cursory dismissal of mid oceanic ridge emissions, ignores all other forms of submarine volcanism altogether. If we take the Smithsonian Institute's list of more than 1000 potentially active subaerial volcanoes worldwide, Kerrick's 10% is reduced to 1-3%.

According to Batiza (1982), Pacific mid-plate seamounts number between 22,000 and 55,000, of which 2,000 are active volcanoes. However, none of the more than 2,000 active submarine volcanoes have been discussed in Kerrick (2001). Furthermore, Kerrick (2001) justifies the omission of mid oceanic ridge emissions by claiming that mid oceanic ridges discharge less CO2 than is consumed by mid oceanic ridge hydrothermal carbonate systems. In point of fact, CO2 escapes carbonate formation in these hydrothermal vent systems in such quantities that, under special conditions, it accumulates in submarine lakes of liquid CO2 (Sakai, 1990; Lupton et al., 2006; Inagaki et al., 2006). Although these lakes are prevented from escaping directly to the surface or into solution in the ocean, there is nothing to prevent superheated CO2 that fails to condense from dissolving into the seawater or otherwise making its way to the surface. It is a fact that a significant amount of mid oceanic ridge emissions are not sequestered by hydrothermal processes; a fact which is neglected by Kerrick (2001), who contends that mid oceanic ridges may be a net sink for CO2. This may well sound reasonable except for the rather small detail that seawater in the vicinity of hydrothermal vent systems is saturated with CO2 (Sakai, 1990) and as seawater elsewhere is not saturated with CO2, it stands to reason that this saturation is sourced to the hydrothermal vent system. If the vent system consumed more CO2 than it emitted, the seawater in the vicinity of hydrothermal vent systems would be CO2 depleted.

---

Bei einigen der genannten Vulkane, deren Aktivität keine Rolle zu spielen scheint, von der ich mich aber auf Grund eines Hobbys habe persönlich überzeugen können, wundert es mich schon. Z.B. der Pacaya, welcher seit Jahrzehnten ununterbrochen aktiv ist und die Aktivität des "Lake Toba" welcher als gigantischer See auf Sumatra zu finden ist, aber eigentlich nichts anderes als einen mit Wasser gefüllter Krater darstellt. Bei einer Reise um den See kann man sich von den vulkanischen Aktivitäten des Toba in Form von Schwefel-Fumarolen überzeugen.
Einen sehr interessanten Artikel der ETH Zürich zu diesem Thema möchte ich noch empfehlen:
http://www.perplex.ethz.ch/papers/connolly_eth_04.pdf

Viele Grüße, Erling Plaethe