Influence of volcanic eruption on Earth climate

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bomohwkl
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Influence of volcanic eruption on Earth climate

Post: # 6226Post bomohwkl »

Title: Krakatoa's signature persists in the ocean
Author(s): Gleckler PJ, Wigley TML, Santer BD, Gregory JM, AchutaRao K, Taylor KE
Source: NATURE 439 (7077): 675-675 FEB 9 2006
Document Type: Editorial Material
Language: English
Cited References: 6 Times Cited: 0

This huge eruption slowed sea-level rise and ocean warming well into the following century.
We have analysed a suite of 12 state-ofthe-art climate models and show that
ocean warming and sea-level rise in the twentieth century were substantially
reduced by the colossal eruption in 1883 of the volcano Krakatoa in the Sunda
strait, Indonesia. Volcanically induced cooling of the ocean surface penetrated
into deeper layers, where it persisted for decades after the event. This remarkable
effect on oceanic thermal structure is longer lasting than has previously been
suspected and is sufficient to offset a large fraction of ocean warming and sea-level
rise caused by anthropogenic influences.
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In model simulations, Krakatoa has long-lasting effects, offsetting a large fraction of the changes in ocean heat content and thermal expansion caused by twentieth-century anthropogenic influences. These results are robust to current uncertainties in climate models and in the historical forcings applied to them. Inclusion of volcanic forcing from
Krakatoa (and, by implication, from even earlier eruptions) is important for a
reliable simulation of historical increases in ocean heat content and sea-level
change due to thermal expansion.
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bomohwkl
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Post: # 6227Post bomohwkl »

Title: Volcanic eruptions and climate
Author(s): Robock A
Source: REVIEWS OF GEOPHYSICS 38 (2): 191-219 MAY 2000
Document Type: Review
Language: English
Cited References: 171 Times Cited: 138
Abstract: Volcanic eruptions are an important natural cause of climate change on many timescales. A new capability to predict the climatic response to a large tropical eruption for the succeeding 2 years will prove valuable to society. In addition, to detect and attribute anthropogenic influences on climate, including effects of greenhouse gases, aerosols, and ozone-depleting chemicals, it is crucial to quantify the natural fluctuations so as to separate them from anthropogenic fluctuations in the climate record. Studying the responses of climate to volcanic eruptions also helps us to better understand important radiative and dynamical processes that respond in the climate system to both natural and anthropogenic forcings. Furthermore, modeling the effects of volcanic eruptions helps us to improve climate models that are needed to study anthropogenic effects. Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about 1 year. Large ash particles fall out much quicker. The radiative and chemical effects of this aerosol cloud produce responses in the climate system. By scattering some solar radiation back to space, the aerosols cool the surface, but by absorbing both solar and terrestrial radiation, the aerosol layer heats the stratosphere. For a tropical eruption this heating is larger in the tropics than in the high latitudes, producing an enhanced pole-to-equator temperature gradient, especially in winter. In the Northern Hemisphere winter this enhanced gradient produces a stronger polar vortex, and this stronger jet stream produces a characteristic stationary wave pattern of tropospheric circulation, resulting in winter warming of Northern Hemisphere continents. This indirect advective effect on temperature is stronger than the radiative cooling effect that dominates at lower latitudes and in the summer. The volcanic aerosols also serve as surfaces for heterogeneous chemical reactions that destroy stratospheric ozone, which lowers ultraviolet absorption and reduces the radiative heating in the lower stratosphere, but the net effect is still heating. Because this chemical effect depends on the presence of anthropogenic chlorine, it has only become important in recent decades. For a few days after an eruption the amplitude of the diurnal cycle of surface air temperature is reduced under the cloud. On a much longer timescale, volcanic effects played a large role in interdecadal climate change of the Little Ice Age. There is no perfect index of past volcanism, but more ice cores from Greenland and Antarctica will improve the record. There is no evidence that volcanic eruptions produce El Nino events, but the climatic effects of El Nino and volcanic eruptions must be separated to understand the climatic response to each
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bomohwkl
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Re: Influence of volcanic eruption on Earth climate

Post: # 12361Post bomohwkl »

http://www.nature.com/news/2009/090917/ ... 9.926.html

[quote]Geologists are desperately trying to gather data in an attempt to understand how global warming will affect violent geological activity.

As increasing atmospheric carbon dioxide levels warm the planet, the problems associated with melting ice won't just raise sea-levels; they will also uncap volcanoes. But just when and how these unstable magmatic beasts will blow in a warmer world is hard to predict.

"The fact is we are causing future contemporary climate change. [Geological hazards are] another portfolio of things we haven't thought of," says Bill McGuire from the Aon Benfield UCL Hazard Research Centre at University College London. He organized a meeting of volcanologists and oceanographers at the university on 15–17 September to draw attention to the problem. [/quote]
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Rezo
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Re: Influence of volcanic eruption on Earth climate

Post: # 12736Post Rezo »

"Autopsy of a eruption: Linking crystal growth to volcano seismicity"

http://phys.org/news/2012-05-autopsy-er ... rowth.html
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