Metano: Seguimiento y temas relacionados

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Re:Metano: Seguimiento y temas relacionados
« Respuesta #60 en: Viernes 05 Marzo 2010 12:04:07 pm »
Parece que se confirma aumento de emisiones de metano provinientes del permafrost:

http://es.noticias.yahoo.com/12/20100305/ten-descubierta-una-gran-fuga-de-metano-5823964.html

Se trata de un artículo publicado en "Science".

Algunos extractos:

"Este descubrimiento pone en evidencia una fuente de metano importante pero hasta ahora abandonada proveniente del permafrost (suelo congelado en forma permanente) ubicado bajo el agua más que sobre la tierra", escriben los autores del estudio, quienes agregan que "estas emisiones corren el riesgo de provocar en el futuro un efecto dramático en el calentamiento global".

Los científicos consideraron durante mucho tiempo que el permafrost ubicado bajo el océano Ártico constituía una barrera infranqueable para el metano, un gas cuyo efecto invernadero es 30 veces superior al del dióxido de carbono (CO2). Pero las observaciones del equipo de la universidad de Fairbanks muestran que el permafrost submarino está perforado y deja escapar grandes cantidades de metano.

El permafrost situado bajo el fondo del océano contiene grandes cantidades de carbono y los expertos temen que el metano que libera lleve al aumento de las temperaturas atmosféricas, causando la liberación, en un circulo vicioso, de una mayor cantidad de metano del permafrost y un calentamiento más importante", explican los autores del estudio.

La concentración media actual de metano en el Ártico es de aproximadamente 1,85 partes por millón, la más elevada desde hace 400.000 años, destaca Natalia Chakhova.


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Re:Metano: Seguimiento y temas relacionados
« Respuesta #61 en: Viernes 05 Marzo 2010 14:35:02 pm »
En la estación de Alert en Nunavut (Canáda), ésta ha sido la evolución de la concentración de metano desde 1985.
 


http://www.esrl.noaa.gov/gmd/ccgg/iadv/

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Re:Metano: Seguimiento y temas relacionados
« Respuesta #62 en: Miércoles 04 Agosto 2010 00:03:30 am »
Hola,

Interesante tema.  :D

Añado gráfica de concentración de metano en Izaña (Tenerife), sacada de la web indicada por Antón. Se aprecia un leve descenso en los últimos meses:



Saludos.  ;)

Santa Cruz de Tenerife (35 msnm) y Obs. Atmosférico de Izaña (AEMET, Tenerife, 2.364 msnm)
Visita mi blog sobre meteorología "Supranubius": www.supranubius.es

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Re:Metano: Seguimiento y temas relacionados
« Respuesta #63 en: Jueves 28 Abril 2011 05:12:44 am »
El metano globalmente no a parado de subir desde 2007 según se aprecia en esta grafica...



Ojala que este incremento no este relacionado con los últimos informes que hablan sobre un incremento de emisiones del permafrost y el más inquietante hidrato de metano escapando del ártico siberiano, si estos dos se despiertan y liberan sus bastos depósitos de forma abrupta.....:-\  :-X no quiero ni imaginarmelo :o :o :o :o

Las implicaciones...

The methane hydrate feedback revisited

April 25, 2011
Methane release from the not-so-perma-frost is the most dangerous amplifying feedback in the entire carbon cycle (see “NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100“).

Methane (CH4) deserves attention it is such a highly potent greenhouse gas — 25-33 times more powerful than carbon dioxide (CO2) over a 100-year time-horizon, but as much as 100 time more potent over 20 years, according to the latest research!

Last year I reported on a major study in Science that found the vast East Siberian Arctic Shelf methane stores appeared to be destabilizing and venting.  The normally staid National Science Foundation issued a press release warning “Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.”



Now there is a new Geophysical Research Letters study on a paleoclimate analog that may be relevant to humanity today, “Methane and environmental change during the Paleocene‐Eocene thermal maximum (PETM): Modeling the PETM onset as a two‐stage event.”

Skeptical Science has a great analysis of the study, which I repost below in its entirety:



Wakening the Kraken
Posted on 23 April 2011 by Agnostic & Daniel Bailey


Methane (CH4) is an extremely potent greenhouse gas, 20-30 times more powerful than carbon dioxide (CO2) on a century timescale.  Fortunately it normally occurs in very low concentration in the atmosphere – about 0.3 to 0.4ppm during glacial periods and 0.6 to 0.7ppm during warmer periods.

In 1750 the concentration was ~0.7ppm.  By 2010 it had reached >1.8ppm, and is now at its highest level in 500,000 years.  This is largely due to human activity, particularly the keeping of large herds of cattle and flocks of chickens and the production of fossil fuels.  Methane has a relatively short life in the atmosphere where it oxidizes into CO2 over a period of 9-15 years.

Large amounts of methane are produced in anaerobic conditions by bacterial activity in the sediments below the seabed as well as by chemical transformation of organic matter at greater burial depths. Methane hydrates are formed by bonding with water to make an ice-like substance in certain temperature/pressure conditions that can be found at shallow water depths in polar regions.  It yields 164 m3 of CH4 per m3 of solid clathrate.

Like Savoir Faire, Clathrates are seemingly everywhere
Clathrate occurs in the Antarctic and particularly in the Arctic where it is abundant in the relatively shallow though very cold seabed of the vast continental shelves which almost encircle the Arctic Ocean.  It also occurs in the sea bed of warmer waters where they are of sufficient depth to enable it to remain stable.

Methane clathrate has accumulated below the seabed over millions of years.  Billions of tons of it lie dormant beneath permafrost, in the pores of sandstones or shrouded in silt.  As long as it remains under pressure or in cold conditions (below 0°C) it is stable and does not release methane.

We know that in the past there have been sudden changes in global warming associated with releases of greenhouse gases.  These rapid, massive releases were characterised by unusual deficiency in carbon isotope 13 (∂13C ) and massive extinction of animals, most recently at the time of the Paleocene-Eocene Thermal Maximum (PETM), about 55.8 million years ago.


The world at the approximate time of the PETM (courtesy Christopher Scotese)


It is believed that the PETM was likely initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth.  This in turn, over many thousands of years, triggered natural climate change, amplified by CH4 releases characterised by a ∂13C deficiency.

A major difference between the PETM (Natural) and present (Anthropogenic) global warming is that the former was likely initiated by increased exposure to solar radiation causing carbon feedbacks and rapid global warming.  The latter, geologically sudden increase is primarily caused by the on-going burning of fossil fuels, which yearly inject a massive bolus of CO2 in the atmosphere, initiating further carbon feedbacks.

Natural global warming is self-rectifying either by slow chemical weathering processes responsible for mineral sequestration of carbon or by gradual return of Earth’s orbital parameters to what they were before the onset of global warming, thereby significantly reducing the amount of solar radiation reaching the Earth’s surface.  The result is cooling oceans able to gradually absorb and lower atmospheric CO2, enabling restoration of albedo at higher latitude/altitude, producing further slow global cooling. This explains why post-maximum temperatures are slow to fall.  The mechanism for reducing anthropogenic global warming, initiated through radiative forcing of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks.

I know what you’re thinking: Was it one shot or two?
Carozza et al (2011) find that natural global warming occurred in 2 stages:  First, global warming of 3° to 9° C accompanied by a large bolus of organic carbon released to the atmosphere through the burning of terrestrial biomass (Kurtz et al, 2003) over approximately a 50-year period; second,  a catastrophic release of methane hydrate from sediment, followed by the oxidation of a part of this methane gas in the water column and the escape of the remaining CH4 to the atmosphere over a 50-year period.

The description of Stage 2:  Very rapid and massive release of carbon deficient in ∂13C, does put one in mind of the Methane Gun hypothesis. It postulates that methane clathrate at shallow depth begins melting and through the feed-back process accelerate atmospheric and oceanic warming, melting even larger and deeper clathrate deposits.  The result:  A relatively sudden massive venting of methane – the firing of the Methane Gun.  Recent discovery by Davy et al (2010) of kilometer-wide (ten 8-11 kilometer and about 1,000 1-kilometer-wide features) eruption craters on the Chatham Rise seafloor off New Zealand adds further ammunition to the Methane Gun hypothesis.

It has been known for many years that methane is being emitted from Siberian swamplands hitherto covered by permafrost, trapping an estimated 1,000 billion tons of methane.  Permafrost on land is now seasonally melting and with each season melting it at greater depth, ensuring that each year methane venting from this source increases.

Methane clathrate has accumulated over the East Siberian continental shelf where it is covered by sediment and seawater up to 50 meters deep.  An estimated 1,400 billion tons of methane is stored in these deposits.  By comparison, total human greenhouse gas emissions (including CO2) since 1750 amount to some 350 billion tons.

Significant methane release can occur when on-shore permafrost is thawed by a warmer atmosphere (unlikely to occur in significance on less than a century timescale) and undersea clathrate at relatively shallow depths is melted by warming water.  This is now occurring. In both cases, methane gas bubbles to the surface with little or no oxidation, entering the atmosphere as CH4 – a powerful greenhouse gas which increases local, then Arctic atmospheric and ocean temperature, resulting in progressively deeper and larger deposits of clathrate melting.

Methane released from deeper deposits such as those found off Svalbard has to pass through a much higher water column (>300 meters) before reaching the surface.  As it does so, it oxidises to CO2, dissolving in seawater or reaching the atmosphere as CO2 which causes far slower warming, but can nevertheless contribute to ocean acidification.

A significant release of methane due to melting of the vast deposits trapped by permafrost and clathrate in the Arctic would result in massive loss of oxygen, particularly in the Arctic ocean but also in the atmosphere.  Resulting hypoxic conditions would cause large extinctions, especially of water breathing animals, which is what we find at the PETM.

Shakhova et al (2010) reports that the continental shelf of East Central Siberia (ECS), with an area of over 2 million km2, is emitting more methane than all other ocean sources combined.  She calculates that methane venting from the ECS is now in the order of 8 million tons per annum and increasing.  This equates to ~200 million tons/annum of CO2, more than the combined CO2 emissions of Scandinavia and the Benelux countries in 2007.  This methane is likely sourced from non-hydrate methane previously kept in place by thin and now melting permafrost at the sea bed, melting clathrates, or some combination of both.

Release of ECS methane is already contributing to Arctic amplification resulting in temperature increase exceeding twice the global average.  The rate of release from the tundra alone is predicted to reach 1.5 billion tons of carbon per annum before 2030, contributing to accelerated climate change, perhaps resulting in sustained decadal doubling of ice loss causing collapse of the Greenland Ice Sheet (Hansen et al, 2011).  This would result in a possible sea level rise of ~5 meters before 2100, according to Hansen et al.

Evidence supports the theory that sudden and massive releases of greenhouse gases, including methane, caused decade-scale climate changes – with consequent species extinctions – culminating in the Holocene Thermal Optimum.

‘Ware the Kraken
In summary, immense quantities of methane clathrate have been identified in the Arctic.  Were a fraction of these to melt, the result would be massive release of carbon, initially as CH4 causing deeper clathrate to melt and oxidise, adding CO2 to the atmosphere.  Were this to occur, it would greatly worsen global warming.

While natural global warming during the ice ages was initiated by increased solar radiation caused by cyclic changes to Earth’s orbital parameters, there is no evident mechanism for correcting Anthropogenic Global Warming over the next several centuries.  The latter has already begun producing methane and CO2 in the Arctic, starting a feedback process which may lead to uncontrollable, very dangerous global warming, akin to that which occurred at the PETM.

This extremis we ignore – to our peril.

– Agnostic & Daniel Bailey

JR: It is worth noting that no climate model currently incorporates the amplifying feedback from methane released by a defrosting tundra. Indeed the NSIDC/NOAA study I wrote about in February on methane release by the land-based permafrost itself doesn’t even incorporate the carbon released by the permafrost carbon feedback into its warming model!

As I wrote last year, the nations of the world should immediately begin emergency methane monitoring across the entire permafrost region — and, of course, aggressive GHG mitigation.  The risk of abrupt climate change is simply too grave to not treat as the most serious preventable problem now facing the human race as a whole.

Fuente:The methane hydrate feedback revisited
« Última modificación: Jueves 28 Abril 2011 05:35:51 am por Doom »

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Re:Metano: Seguimiento y temas relacionados
« Respuesta #65 en: Sábado 17 Diciembre 2011 23:13:01 pm »
Dejo un articulo muy interesante que muestra la importancia que tiene el artico en la estabilidad climatica del planeta.....

Si los moderadores creen que puede ir en otro lugar mejor que este, doy permiso a que lo mueban

Arctic methane: Russian researchers report

I vowed not to talk about this because it literally makes me sick to my stomach, but it's too important to deny. We all know about the vast deposits of methane clathrates on the Siberian continental shelf. They are kept in place by pressure and low temperatures. However, the temperatures (SAT as well as SST) are getting less and less low in the Arctic, so in theory it could mean that these deposits come loose and leave the ocean floor to end up in the atmosphere. Methane is a much more potent greenhouse gas than CO2 and some extinction events in the distant past have been linked to the deadly feedback of warming->methane release->more warming->more methane release->etc.

No one is really sure what is going on exactly with those methane deposits, but in the past years there has been much speculation (undoubtedly caused by the spectacular retreat of summer sea ice in the region) and reporting of a probable increase of methane bubbling up from the Siberian continental shelf. And so the results of this year's Russian research mission were eagerly awaited. Mind you, not by me.

It seems the results are in and were reported at AGU last week.
The Independent reports with this article:


Shock as retreat of Arctic sea ice releases deadly greenhouse gas
Russian research team astonished after finding 'fountains' of methane bubbling to surface

Dramatic and unprecedented plumes of methane – a greenhouse gas 20 times more potent than carbon dioxide – have been seen bubbling to the surface of the Arctic Ocean by scientists undertaking an extensive survey of the region.

The scale and volume of the methane release has astonished the head of the Russian research team who has been surveying the seabed of the East Siberian Arctic Shelf off northern Russia for nearly 20 years.

In an exclusive interview with The Independent, Igor Semiletov, of the Far Eastern branch of the Russian Academy of Sciences, said that he has never before witnessed the scale and force of the methane being released from beneath the Arctic seabed.

"Earlier we found torch-like structures like this but they were only tens of metres in diameter. This is the first time that we've found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It's amazing," Dr Semiletov said. "I was most impressed by the sheer scale and high density of the plumes. Over a relatively small area we found more than 100, but over a wider area there should be thousands of them."

Scientists estimate that there are hundreds of millions of tonnes of methane gas locked away beneath the Arctic permafrost, which extends from the mainland into the seabed of the relatively shallow sea of the East Siberian Arctic Shelf. One of the greatest fears is that with the disappearance of the Arctic sea-ice in summer, and rapidly rising temperatures across the entire region, which are already melting the Siberian permafrost, the trapped methane could be suddenly released into the atmosphere leading to rapid and severe climate change.

Dr Semiletov's team published a study in 2010 estimating that the methane emissions from this region were about eight million tonnes a year, but the latest expedition suggests this is a significant underestimate of the phenomenon.

Continue reading here...

I guess this is the graph to keep an eye on (courtesy of Al Rodger):


The numbers for this graph were derived from NOAA's Earth System Research Laboratory.

The increase in global atmospheric methane concentrations had slowed down for a while, but has picked up again since 2006, as reported by the World Meteorological Organization (via ClimateProgress):

Methane (CH4) contributes about 18% to the overall global increase in radiative forcing since 1750 and is the second most important greenhouse gas after carbon dioxide.

Before the start of the industrial era, atmospheric methane was about 700 parts per billion (number of molecules of the gas per billion molecules of dry air) Since 1750, it has increased 158%, mostly because of activities such as cattle-rearing, rice planting, fossil fuel exploitation and landfills. Human activities now account for 60% of methane emissions, with the remaining 40% being from natural sources such as wetlands.

After a period of temporary relative stabilization from 1999 to 2006, atmospheric methane has again risen. Scientists are conducting research into the reasons for this, including the potential role of the thawing of the methane-rich Northern permafrost and increased emissions from tropical wetlands.

There's more info in this excellent SkS post from earlier this year: Wakening the Kraken

Fuente:
http://neven1.typepad.com/blog/2011/12/arctic-methane-russian-researchers-report.html
http://www.independent.co.uk/environment/climate-change/shock-as-retreat-of-arctic-sea-ice-releases-deadly-greenhouse-gas-6276134.html

In memoriam: Albert A. Bartlett
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"Hay que tener la mente abierta. Pero no tanto como para que se te caiga el cerebro al suelo."
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Re:Metano: Seguimiento y temas relacionados
« Respuesta #67 en: Domingo 18 Diciembre 2011 15:40:31 pm »
Methane Time Bomb in Arctic Seas – Apocalypse Not

Paper Abstract..

ARE RECENT INCREASES IN ATMOSPHERIC METHANE RELATED TO ARCTIC CLIMATE CHANGE?
Are Recent Increases in Atmospheric Methane Related to Arctic Climate Change?
Abstract Category:  2.3. Arctic Change and Natural Variability
Type:  Poster
Molly Heller1, Andrew Crotwell2, Lori Bruhwiler3, Russell Schnell4, Ed Dlugokencky5
1NOAA Earth System Research Laboratory/CIRES University of Colorado, Boulder, CO, USA, [email protected]
2NOAA Earth System Research Laboratory/CIRES University of Colorado, Boulder, CO, USA, [email protected]
3NOAA Earth System Research Laboratory, Boulder, CO, USA, [email protected]
4NOAA Earth System Research Laboratory, Boulder, CO, USA, [email protected]
5NOAA Earth System Research Laboratory, Boulder, CO, USA, [email protected]
Atmospheric methane (CH4), a strong greenhouse gas, affects background air quality because it is a precursor for O3 production. Measurements of atmospheric CH4 from air samples collected weekly at 46 remote surface sites show that after a decade of near-zero growth, globally averaged atmospheric methane increased during 2007 and 2008. During 2007, CH4 increased by 7.7±0.2 ppb. CH4 mole fractions averaged over polar northern latitudes and the southern hemisphere increased more than other zonally averaged regions. In 2008, globally averaged CH4 increased by 6.9±0.2 ppb; the largest increase was in the tropics, while polar northern latitudes did not increase. During the first half of 2009, globally averaged atmospheric CH4 was ~7 ppb greater than it was in 2008, suggesting that the increase will continue in 2009. There is the potential for increased CH4 emissions from strong positive climate feedbacks in the Arctic where there are huge stores of carbon in permafrost and hydrates, so the causes of these recent increases must be understood.

The sources typically responsible for interannual variability in CH4 growth rate are wetlands and biomass burning. Satellite and in situ CO observations suggest only a minor contribution to increased CH4 from biomass burning. The most likely drivers of the CH4 anomalies observed during 2007 and 2008 are anomalously high temperatures in the Arctic and greater than average precipitation in the tropics. In the Arctic, the unusual warmth observed during 2007 has been rare, but the occurrence of such conditions is predicted by climate models to become more frequent in the future, with a potentially large positive feedback on climate from the resulting carbon emissions. A return to zero CH4 growth rate in the Arctic during 2008 suggests the 2007 anomaly was part of natural variability, and not yet a sign that feedbacks in the Arctic have emerged as a significant term in the global CH4 budget.

En definitiva hasta hoy no se puede concluir que el aumento de CH4 global mente este relacionado con el aumento de emisiones de este en el ártico, pero lo visto en 2007 y como las condiciones de ese año ,produjo un aumento de las emisiones de CH4 en el ártico , y como es esperable que eventos similares de deshielo y altas temperaturas en el ártico sean más frecuentes en el futuro (2011 fue muy similar) es de esperar que la contribución del ártico al nivel global de CH4 aumente....


In memoriam: Albert A. Bartlett
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Re:Metano: Seguimiento y temas relacionados
« Respuesta #68 en: Domingo 18 Diciembre 2011 17:59:50 pm »
En definitiva hasta hoy no se puede concluir que el aumento de CH4 global mente este relacionado con el aumento de emisiones de este en el ártico, pero lo visto en 2007 y como las condiciones de ese año ,produjo un aumento de las emisiones de CH4 en el ártico , y como es esperable que eventos similares de deshielo y altas temperaturas en el ártico sean más frecuentes en el futuro (2011 fue muy similar) es de esperar que la contribución del ártico al nivel global de CH4 aumente....

Asi me gusta, todo bien controlado...

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Re:Metano: Seguimiento y temas relacionados
« Respuesta #69 en: Lunes 19 Diciembre 2011 00:12:52 am »
The CH4 [methane] supersaturation, recently reported from the eastern Siberian shelf, is believed to be the result of the degradation of subsea permafrost that is due to the long-lasting warming initiated by permafrost submergence about 8000 years ago rather than from those triggered by recent Arctic climate changes.

http://www.agu.org/pubs/crossref/2011/2011JC007218.shtml