I took a straw poll the other day about global warming and about half the people I asked said that they thought that global warming was not happening. This is hilarious because even the active climate sceptics say that global warming is indeed happening but say it is not due to human activity, arguing that it is the result of natural variations.
The most obvious indicator of global warming is the disappearance of the ice cover to the Arctic Ocean (see Arctic Sea Ice News ). My favoured prediction is that the sea ice will all be gone in the summer by about 2015-16 (See Even More Disturbing Events in the Arctic).
Is this serious? Is the sudden disappearance of the arctic ice dangerous? Some groups think that it is very dangerous (See Arctic News Blog). The argument hinges around whether or not the methane stored under the permafrost at the bottom of the Arctic Ocean will be released. Methane is a much more powerful global warming agent than carbon dioxide. If methane is released in the quantities predicted by the Arctic Methane Emergency Group we are gonners in a few years.
Ultimately we can only wait and see. There were disturbing signs of increased methane release in 2011 but this has ameliorated (See Apocalypse 4 Real blog). NASA's Giovanni Portal allows us to view changing methane concentrations on a daily basis (with thanks to the US people and government for providing such facilities).
There is definite evidence of high methane fluxes from the sea off the coast of northern Russia in 2005:
These fluxes result in high local atmospheric methane concentrations:
See Results of the first year of Atmospheric Observations at the International Tiksi Hydrometereological Observatory
These emissions of methane are disturbing because they come from a special store of methane known as "methane clathrates" which is a combination of methane and ice that can be formed at the cold bottom of oceans or at great depth in warmer seas. The good news is that these clathrates are trapped under hundreds of metres of frozen ground and frozen sea floor (permafrost) in the arctic and the bad news is that there is so much methane stored in clathrates that it would easily kill us all through global warming if it were released.
Are we going to suffer a sudden release of methane from methane clathrates? The methane measurements do not, as yet, show any massive increase. The methane release in the Laptev Sea may well be associated with geological activity rather than global warming. A study of the Laptev Sea permafrost in 2003 by Hubberton & Romanovskii brings out this association of thin or fractured permafrost with geological faults:
Also notice that the permafrost is very thick outside the fault zones so that not only are the clathrates capped in place but, if sufficiently exposed so that warming with ground heat from below is dissipated they may become stable because of the high pressure. This is evident from the phase diagram for methane clathrates below where it can be seen that at depths of over 500 m the clathrates are fairly stable:
A recent study by Dmitrenko et al (2011) investigated the Siberian shelf coastal zone and, although the sea had warmed by about 2 degrees C, they found that:
"The permafrost modeling indicates, however, that a significant change in the permafrost depth lags behind the imposed changes in surface temperature, and after 25 years of summer seafloor warming (as observed from 1985 to 2009), the upper boundary of permafrost deepens only by ∼1 m. "
The permafrost is hundreds of metres deep and this may be eroding at only 1 m every 25 years. Given that the permafrost on land is most exposed to warming perhaps we should not be too anxious about methane clathrate release until methane release is obvious on land (once a depth of a couple of hundred metres of permafrost on land have melted).
There are sites of relatively shallow methane clathrates (See Hovlanda and Svensenb 2006) but the extent of these sites is unknown and they represent a smaller area than permafrost covered clathrates. We can only wait and see to discover whether the methane release from such sites will be significant.
Although methane clathrates under the permafrost of the arctic ocean may not be an immediate problem there are considerable amounts of methane in superficial layers of frozen soil. Vonk et al (2012) have considered the erosion of the shoreline and melting of the surface ice deposits on the Russian Arctic coast. Global man-made CO2 emissions amount to about 40 gigatonnes a year and the thawing of the top layers of the soil (the "Ice Complex Deposits") around the East Siberian Arctic Shelf release 0.044 gigatonnes a year.
This release of carbon does not seem to be a significant threat.
Obviously we can never be certain about natural changes, for instance the rapid loss of Arctic sea ice in the summer was not predicted, the clathrates could suddenly release gigatons of methane, but this does not seem probable in the immediate future. Don't panic until you see the methane actually rising, by then it may be too late but now it is definitely too early.
Update 4th February 2013
Oops:
This from the alarmist Arctic News Blog is alarming, lets hope it goes away next month.... It's OK, it did go away (27th Feb).
H.-W. Hubberten & N.N. Romanovskii Permafrost, Phillips, Springman & Arenson (eds) 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7
Dmitrenko, I.A. et al. Recent changes in shelf hydrography in the Siberian Arctic: Potential for subsea permafrost instability. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, C10027, doi:10.1029/2011JC007218, 2011 http://www.agu.org/pubs/crossref/2011/2011JC007218.shtml
Hovlanda, M and Svensenb, H. (2006) Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea. Marine Geology Volume 228, Issues 1–4, 30 April 2006, Pages 15–23
Vonk et al (2012) Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia
Nature 489, 137–140 (06 September 2012) doi:10.1038/nature11392
The most obvious indicator of global warming is the disappearance of the ice cover to the Arctic Ocean (see Arctic Sea Ice News ). My favoured prediction is that the sea ice will all be gone in the summer by about 2015-16 (See Even More Disturbing Events in the Arctic).
Is this serious? Is the sudden disappearance of the arctic ice dangerous? Some groups think that it is very dangerous (See Arctic News Blog). The argument hinges around whether or not the methane stored under the permafrost at the bottom of the Arctic Ocean will be released. Methane is a much more powerful global warming agent than carbon dioxide. If methane is released in the quantities predicted by the Arctic Methane Emergency Group we are gonners in a few years.
Ultimately we can only wait and see. There were disturbing signs of increased methane release in 2011 but this has ameliorated (See Apocalypse 4 Real blog). NASA's Giovanni Portal allows us to view changing methane concentrations on a daily basis (with thanks to the US people and government for providing such facilities).
There is definite evidence of high methane fluxes from the sea off the coast of northern Russia in 2005:
 |
| Methane emissions in the Laptev Sea |
 |
|
These emissions of methane are disturbing because they come from a special store of methane known as "methane clathrates" which is a combination of methane and ice that can be formed at the cold bottom of oceans or at great depth in warmer seas. The good news is that these clathrates are trapped under hundreds of metres of frozen ground and frozen sea floor (permafrost) in the arctic and the bad news is that there is so much methane stored in clathrates that it would easily kill us all through global warming if it were released.
Are we going to suffer a sudden release of methane from methane clathrates? The methane measurements do not, as yet, show any massive increase. The methane release in the Laptev Sea may well be associated with geological activity rather than global warming. A study of the Laptev Sea permafrost in 2003 by Hubberton & Romanovskii brings out this association of thin or fractured permafrost with geological faults:
 |
| Permafrost depth in East Siberian and Laptev Sea region. Hubberton & Romanovskii 2003 http://www.arlis.org/docs/vol1/ICOP/55700698/Pdf/Chapter_077.pdf |
 |
| Methane Clathrate Phase Diagram |
"The permafrost modeling indicates, however, that a significant change in the permafrost depth lags behind the imposed changes in surface temperature, and after 25 years of summer seafloor warming (as observed from 1985 to 2009), the upper boundary of permafrost deepens only by ∼1 m. "
The permafrost is hundreds of metres deep and this may be eroding at only 1 m every 25 years. Given that the permafrost on land is most exposed to warming perhaps we should not be too anxious about methane clathrate release until methane release is obvious on land (once a depth of a couple of hundred metres of permafrost on land have melted).
There are sites of relatively shallow methane clathrates (See Hovlanda and Svensenb 2006) but the extent of these sites is unknown and they represent a smaller area than permafrost covered clathrates. We can only wait and see to discover whether the methane release from such sites will be significant.
Although methane clathrates under the permafrost of the arctic ocean may not be an immediate problem there are considerable amounts of methane in superficial layers of frozen soil. Vonk et al (2012) have considered the erosion of the shoreline and melting of the surface ice deposits on the Russian Arctic coast. Global man-made CO2 emissions amount to about 40 gigatonnes a year and the thawing of the top layers of the soil (the "Ice Complex Deposits") around the East Siberian Arctic Shelf release 0.044 gigatonnes a year.
 |
| Ice Complex Deposits being eroded at the shores of the Laptev Sea |
Obviously we can never be certain about natural changes, for instance the rapid loss of Arctic sea ice in the summer was not predicted, the clathrates could suddenly release gigatons of methane, but this does not seem probable in the immediate future. Don't panic until you see the methane actually rising, by then it may be too late but now it is definitely too early.
Update 4th February 2013
Oops:
H.-W. Hubberten & N.N. Romanovskii Permafrost, Phillips, Springman & Arenson (eds) 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7
Dmitrenko, I.A. et al. Recent changes in shelf hydrography in the Siberian Arctic: Potential for subsea permafrost instability. JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 116, C10027, doi:10.1029/2011JC007218, 2011 http://www.agu.org/pubs/crossref/2011/2011JC007218.shtml
Hovlanda, M and Svensenb, H. (2006) Submarine pingoes: Indicators of shallow gas hydrates in a pockmark at Nyegga, Norwegian Sea. Marine Geology Volume 228, Issues 1–4, 30 April 2006, Pages 15–23
Vonk et al (2012) Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia
Nature 489, 137–140 (06 September 2012) doi:10.1038/nature11392
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