torsdag, september 04, 2008

Methane - Hot Topic

In an earlier post I was asked if I could translate an entry from this blog. If you wonder why me, read the comments on my earlier post and over at the Ellis blog. (It’s hot stuff)

2 September 158/71N aboard the research vessel Smirnitskyi

Yesterday we took samples from the forth of the five biggest Russian rivers in the arctic – Indigirka. It was calm and we used our continuous measurements to trace Indigirka’s plume. It is very shallow here and the ship can’t go in water with a depth less then 10 meters and at some parts that depth isn’t reached until you are tenths of kilometres out from the coast. Finally we saw that our optical measurements of the dissolved organic coal drastically went up at the same time as the salt concentration went down. So sins this night we head 180 nautical miles eastward towards the big erosion coast that we will sample. There we will start a longer transect out from the fifth and most easterly of the biggest rivers – Kolyma. The last hours some drift ice has occurred and just recently we passed a smaller iceberg. As an old song from the gulag time say: Kolyma, Kolyma, 12 months of winter and the rest summer.

Studies of methane discharge from the sea bed in the East Siberian Sea
Since it during the last days have circulated news about the methane discharges in media I thought that I should try to shortly describe these processes. One of the main projects during the Russian – Swedish research expedition International Siberian Shelf Study 2008 (ISSS-08) is more advanced studies of possible flows of methane from the sea bed through water and out in the atmosphere.

At around 110 degrees easterly longitude, when we where wrestling with drift ice in western Laptev Sea, we discovered two new areas where methane concentrations in both the water and in the air above clearly exceeded the normal methane concentration in Arctic. A few days later a new area in the eastern Laptev Sea was discovered at 133 easterly longitudes. In an area of the Lena Rivers outflow next to a fault zone the Russian research leader Igor Semiletov have found increased methane concentration and also published abut it. This was now confirmed as strongly increased methane concentrations where measured. Now some more areas have bean found at the border between the Laptev Sea and the East Siberian Sea.

Semiletov have lead almost ten expeditions in the Laptev Sea since 1994. During the 1990s increased methane concentrations where rarely measured. The expeditions after 2003 have documented an increasing number of hotspots with methane discharge. This Swedish – Russian expedition deeper the knowledge about this with a broader combination of sampling methods and analyses then earlier.

Short about the methane releasing process in the sediments at the Siberian costal sea.
First, methane is around a 20 times stronger greenhouse gas then carbon dioxide. The methane have formed mostly through slow decomposition of organic material that have accumulated from primary production (photosynthesis) on both land and in the sea (oceans). Big methane reservoirs are located in the sea bed both in and under a layer of permafrost.

This permafrost layer where created in this region during the latest “ice age” and some have thought that this frozen layer stops the methane gas from leaking out in the sea water and further to the atmosphere. The sea level at the last ice age where much lower then the present level and the Siberian costal sea where at that time above sea level. When the glaciers melted the sea level rise and the frozen land was flooded.

To release the trapped methane the permafrost have to thaw this could happen in several ways.

1. The overlaying sea water warms the sediment slowly.
2. Geothermal heat – in fault zones (cracks in the earths crust).
3. River plumes gets longer – warm river water thaws up an area of permafrost.

Process 1 and 3 could accelerate because of the greenhouse effect, warmer river water, increased discharge and higher temperature in the water close to land along the east Siberian coast. Data from NOAA show that the average temperature during mars-may in the region have been up to 4 degrees warmer in the beginning of 2000 compared to the last three decades at the end of 1900.

Semiletov suggests that one reason that it might not have been a degaussing earlier is the extreme slow thawing of the permafrost in the frozen sea bed. Now the anthropogenic warming of the northeast Siberian area have lead to increased river discharge and higher temperature on both river water and other costal water which could contribute to an accelerated erosion of the permafrost layer.

It still is to early to draw any conclusions about how this process will effect the climate. In a publication a few years ago Semiletovs calculations showed that the amount of methane already released from the area at that time was as big as the estimation was (at that time) for all the ocean. The ocean (seas) is considered to be an important but not the biggest source of methane to the atmosphere. It is possible that an even bigger methane flow from the Siberian costal sea bed could have a substantial effect on the methane concentration in the overlaying atmosphere. From what I understand there is indications from the ice cores that earlier climate epochs that this have happened before. Since the amount of methane in these shallow depots is vastly big this discoveries calls for further research around these processes.

/Örjan Gustafsson, Research leader, ISSS-08

*Note that this not is an official translation of a text on the research team’s blog. If you find anything wrong with the translation or want to ad anything to the text above feel free to leave a comment about it. My English is not the best and this was done in a hurry, but I hope you still find the translation satisfying.

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Update:
This links to the original post in Swedish.


3 kommentarer:

Gareth sa...

Magnus, tak!

Belette sa...

Hello.

I;ve left a reply on my blog to your comment, which really says little more than dunno.

Hope you're having fun on the high seas...

Oh no... all the buttons are in Swedish... I hope i press the right one.

Magnus sa...

:) good and tack själva.

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