News Arctic: Methane, Faults and Sea Ice

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Wednesday, 6 November 2013

Methane, Faults and Sea Ice

Shield breaking down

Until now, Arctic sea ice has been acting as a shield, in a number of ways, including:

preventing sunlight from warming up water underneath the sea ice
facilitating currents that currently cool the bottom of the sea
preventing much methane from entering the atmosphere; as discussed in an earlier post, the sea ice collects and holds the methane in places close enough to the surface for the methane to be consumed through photochemical and biochemical oxidation.

However, as the sea ice declines, this shield is breaking down. As a result:

more sunlight is reaching the water, contributing to warming of water in the Arctic Ocean
sea ice decline comes with the danger of weakened currents that cool the seabed
more methane is able to penetrate the cracks and openings in the ever-thinner ice.

Warm Water traveling along Gulf Stream

At the same time, global warming is causing more extreme weather events to occur, such as the record warmth observed in July 2013 in part of the northeastern Atlantic Ocean off the coast of North America. As discussed in a recent post, this warm water has meanwhile traveled along the Gulf Stream and reached the Arctic Ocean.

Methane venting from Seabed

As a result, warmer water is now destabilizing sediments under the seabed that hold huge amounts of methane in the form of free gas and hydrates. Methane is now venting from the seabed of the Arctic Ocean, driven by sea ice decline and “by Gulf Stream heating, earthquakes and deep pyroclastic eruptions”, as Malcolm Light explains in a recent comment and as described in an earlier post.

The image below shows the result: Massive amounts of methane venting from the seabed, penetrating the sea ice, and entering the atmosphere over the Arctic Ocean.

Methane, Faults and Sea Ice

The animation below illustrates links between:

The fault line that crosses the Arctic Ocean and forms the boundery between two tectonic plates (i.e. the North American Plate and the Eurasian Plate)
Arctic sea ice, which until now has acted as a shield
The prominence of high methane readings over the Arctic Ocean

[ this animation is a 1.67 MB file that may take some time to fully load ]

Above animation illustrates high methane readings (1950 ppb and higher, in yellow) prominently showing up within the bounderies of the sea ice, and especially along the Gakkel Ridge and Laptev Sea Rift parts of the fault line that crosses the Arctic Ocean.

Below a combination of three images by Dr. Leonid Yurganov confirming that methane levels have intensified during October 2013, especially over the Laptev Sea.

[ click on image to enlarge ]

Below, a Naval Research Laboratory animation showing ice thickness over 30 days.

Arctic Cyclone Alert

As above Naval Research Laboratory animation shows, sea ice is less than one meter thick in areas where increases have occurred over the past 30 days. At the same time, a lot of the two-meters thick ice is moving out of the Arctic Ocean along the north coast of Greenland, and this process could increase if the development of a cyclone over the Arctic Ocean persists, as forecast on the Naval Research Laboratory image below.

Paul Beckwith warns: “The Arctic sea ice should be rapidly gaining volume this time of year. The cyclone can prevent this. This cyclone can rapidly move the thickest ridged ice out of the basin via the Fram Strait counteracting the volume increase of freezing thinner ice.”

Albert Kallio adds: “Arctic Ocean ice cover is also in flux and pulvirisation since summer has lowered viscosity of sea ice to the point where it behaves almost like liquid, with loads and loads of thick but broken ice thrusted into the Atlantic Ocean where it rapidly melts away in warm waters.”

Thick ice needed for sea ice to act as shield

Below is an animation, from an earlier post, showing an image by Leonid Yurganov with methane readings for end January 2013 against a map showing sea ice concentrations for January 2013, from the National Snow and Ice data Center (NSIDC). The animation shows that high methane readings are prominent over water without sea ice or only thin sea ice.

High levels of methane over water without sea ice end January 2013 [ 1.84 MB file ]

The above animation shows that, back in January 2013, when the sea ice was much thicker. Comparison with the end January 2013 Naval Research Laboratory image below indicates that sea ice must be at least 1m thick to be able to act as a shield.