Arctic News: volcanoes

Showing posts with label volcanoes. Show all posts

Friday, October 30, 2015

Methane Vent Hole In Arctic Sea Ice?

Methane vent hole in the ice?

In October 2015, an area appeared in the Arctic sea ice where the temperature of the ice was a few degrees Celsius higher and where ice concentration and salinity levels were substantially lower than the surrounding ice. The image below pictures the situation on October 11, 2015.

[ click on image to enlarge ]

Could this have been an iceberg? If so, ice concentration should have been higher, rather than lower. More likely is that this is a vent hole with methane rising through cracks in the sea ice.

Malcolm Light comments: "The whole of the Arctic seabed is covered with methane hydrates and NASA satellites should have long ago defined where the major plumes were coming out. It is clearly a surface methane vent hole in the ocean ice analogous to the large methane vent holes that appeared all over northern Siberia this year. It means we have overheated the Arctic seafloor to the extent where the methane hydrates are now unstable and we could have further major releases at any time. We have already lit the fuse on a giant methane subsea permafrost bomb in the Arctic which can go off at any moment."

Roger Caldwell responds: "I think it's upwelling warm water. There is a ridge right below the spot. I can see warm spots through the ice on the nullschool program. The warm water comes through the Bering Strait and sinks to the mid levels. When it gets to the ridge it flows upward, making a temporary polynya."

The image below shows warm water entering the Arctic Ocean from the Pacific Ocean (through the Bering Strait) and the Atlantic Ocean, with the dark-red color of many areas in the Arctic Ocean indicating warm waters, including an area close to the North Pole marked by the red circle. So, the spot could indeed be a polynya caused by upwelling of warm water. Alternatively to the Pacific Ocean, the warm water could have originated from the Atlantic Ocean. In the Fram Strait, near Svalbard, sea surface temperatures as high as 11.9°C or 53.5°F were recorded on October 28, 2015, i.e. 9.6°C or 17.2°F warmer than 1981-2011 (at the location marked by the green circle).

[ click on image to enlarge ]

Of course, with water this warm reaching the center of the Arctic Ocean, the threat that this will cause (further) destabilization of methane hydrates at the seafloor of the Arctic Ocean is equally ominous. The more recent image below shows warm waters in the Arctic Ocean in a different way, partly because the anomaly is calculated from the period 1961 to 1990.

The image below shows that sea surface temperatures as high as 12°C or 53.5°F were recorded near Svalbard on October 31, 2015, i.e. 9.7°C or 17.4°F warmer than 1981-2011 (at the location marked by the green circle).

[ click on image to enlarge ]

On the image below, Malcolm Light added the Gakkel Ridge, i.e. the fault line that extends on the seafloor of the Arctic Ocean from the northern tip of Greenland to Siberia (red line), and the location of explosive volcanoes (lilac spot), with content from Sohn et al., 2008.

A zone of increased heat near the North Pole which may be related to large quantities of gas released from a group of extremely pyroclastic carbon dioxide-rich volcanoes located at the Gakkel Ridge

The table below shows the height that emerging carbon dioxide plumes can be expected to reach for a given carbon dioxide volume fraction in the foam at the top of a magma chamber.

Malcolm Light adds:
"Sohn et al. (2007) outlined how the sequence of extreme pyroclastic eruptions occur along the Gakkel Ridge (85°E volcanoes) at an ultra-slow plate spreading rate (<15-20 mm/year). These volcanoes formed from the explosive eruption of gas-rich magmatic foams. Long intervals between eruptions with slow spreading caused huge gas (volatile) build up high storage pressures, deep in the crust.

Extension of the 85°E seismic swarm occurred over 3 months but later earthquakes were caused by large implosions from the explosive discharge of pressurized magmatic foam from a deep-lying magma chamber through the fractured chamber roof which rapidly accelerated vertically, expanded and decompressed. There were many periods of widespread explosive gas discharge from 1999 over two years detected by small-magnitude sound signals from seismic networks on the ice.

Pyroclastic rocks contain bubble wall fragments and were widely distributed over an area of more than 10 square km. Deep fragmentation was caused by the accumulation of a gas (volatile) foam within the magma chamber which then fractured, formed a pyroclastic fountain 1-2 km high in the Arctic Ocean and spread the pyroclastic material over a region whose size was proportional to the depth of the magma chamber (see above table). A volatile carbon dioxide content of 14% (Wt./Wt. - volume fraction 75%) is necessary at 4 km depth in the Arctic Ocean to fragment the erupting magma."

As said, with water this warm reaching the center of the Arctic Ocean from the Atlantic and Pacific Oceans, the threat is that added heat from volcanic activity or pressure shocks from underwater earthquakes or landslides will trigger (further) destabilization of methane hydrates at the seafloor of the Arctic Ocean.

Below follows some more background.

Animations

Naval Research Laboratory 30-day animations are added below for temperature, concentration, salinity and thickness of the sea ice. Click on each of them to view full versions.

Temperature		Concentration
Salinity		Thickness

[ click on animations to enlarge ]

Background on tectonic plates and faults

A major fault line crosses the Arctic Ocean, forming the boundary between two tectonic plates, the North American Plate and the Eurasian Plate. These plates slowly diverge, creating seismic tension along the fault line. From where the Mid-Atlantic ridge enters the Arctic Ocean, it is called the Gakkel Ridge. The fault continues as the Laptev Sea Rift, on to a transitional deformation zone in the Chersky Range in Siberia, then the Ulakhan Fault between the North American Plate and the Okhotsk Plate, and then continues as the Aleutian Trench to the end of the Queen Charlotte Fault system.

The situation in October 2013

High methane readings were recorded for a period of just over one day, October 19 - 20, 2013, as shown in the images below. Indicated in yellow are all methane readings of 1950 ppb and over.

To pointpoint more closely where methane is venting along the Laptev Sea Rift, the image below gives readings for October 20, 2013, pm, at just three altitudes (607 - 650 mb).

Satellite measurements recorded methane readings of up to 2411 ppb on October 20, 2013.

Methane venting in the Laptev Sea in 2005 and 2007

For further reference, large amounts of methane have been venting in the Laptev Sea area in previous years. Added below is an edited part of a previous post, Unfolding Climate Catastrophe.

In September 2005, extremely high concentrations of methane (over 8000 ppb, see image on the right) were measured in the atmospheric layer above the sea surface of the East Siberian Shelf, along with anomalously high concentrations of dissolved methane in the water column (up to 560 nM, or 12000% of super saturation).

The authors conclude: "Since the area of geological disjunctives (fault zones, tectonically and seismically active areas) within the Siberian Arctic shelf composes not less than 1-2% of the total area and area of open taliks (area of melt through permafrost), acting as a pathway for methane escape within the Siberian Arctic shelf reaches up to 5-10% of the total area, we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time".

In 2007, concentrations of dissolved methane in the water column reached a level of over 5141 nM at a location in the Laptev Sea. For more background, see the previous post, Unfolding Climate Catastrophe.

Methane levels in October 2015

The image below shows high methane concentrations over the Arctic Ocean on October 11, 2015, pm, at 840 mb, i.e. relatively close to sea level.

The image below shows high levels of methane over the Arctic Ocean at higher altitude (469 mb) on October 28, 2015, pm, when methane levels were as high as 2345 ppb.

Note that the above two images have different scales. The data are from different satellites. The video below shows images from the MetOp-2 satellite, October 31, 2015, p.m., at altitudes from 3,483 to 34,759 ft or about 1 to 11 km (241 - 892 mb).

Peak methane levels were as high as 2450 ppb on November 1, 2015.

Update: Warm Water in Arctic Ocean

On November 5, 2015, sea surface temperatures as high as 8.5°C or 47.3°F showed up in the Bering Strait, an anomaly of 6.6°C or 11.9°F, while sea surface temperatures as high as 14.4°C or 57.9°F showed up near Svalbard on November 5, 2015, a 12.2°C or 22°F anomaly. The situation is illustrated by the image below.

[ click on image to enlarge ]

These high temperatures indicate that the sea can be a lot warmer below the surface than at the surface, and it appears that very warm waters are continuing to enter the Arctic Ocean from both the Pacific Ocean and the Atlantic Ocean. As discussed in previous posts such as this one, the danger is that ever warmer waters will (further) destabilize methane hydrates at the seafloor of the Arctic Ocean, resulting in abrupt methane eruptions that could dwarf the impact of existing greenhouse gases in the atmosphere.

Climate Plan

The situation is dire and calls for comprehensive and effective action, as discussed at the Climate Plan.

Links

- Explosive volcanism on the ultraslow-spreading Gakkel ridge, Arctic Ocean, Sohn et al. (2007, published 2008)
http://www.nature.com/nature/journal/v453/n7199/full/nature07075.html

- Unfolding Methane Catastrophe
http://arctic-news.blogspot.com/2013/10/unfolding-methane-catastrophe.html

- Further Confirmation of a Probable Arctic Sea Ice Loss by Late 2015, by Malcolm P.R. Light (Sep. 1, 2012)
http://arctic-news.blogspot.com/2012/09/further-confirmation-of-a-probable-arctic-sea-ice-loss-by-late-2015-loss.html

In October 2015, an area appeared in the Arctic sea ice where the temperature of the ice was a few degrees Celsius...
Posted by Sam Carana on Friday, October 30, 2015

Saturday, August 30, 2014

Ring Of Ice

Prominence of earthquakes in North America and around Greenland has prompted a team of researchers led by Arctic-news blog editor Sam Carana to coin the phrase “Ring Of Ice” to describe what they see happening in the Arctic.

“Melting of ice in north Canada and on Greenland is causing pressure changes, resulting in seismic activity”, explains Sam Carana.

Heavy seismic activity is ocurring along the faultlines that constitute the border of the North American Plate, similar to the the heavy activity along the Ring Of Fire around the Pacific Ocean.

Seismic activity roughly follows the borders of the North American Plate, which includes Greenland. However, where the major fault bends away to the west following the Aleutian Islands, seismic activity continues north through Alaska along a line that extends over the North Pole toward Svalbard.

This northward path through Alaska is illustrated by the earthquakes on the image below.

“Earthquakes are prominent along the entire border of the North American Plate”, Sam Carana adds, “but they increasingly appear to be taking this shortcut through Alaska and the underlying cause of this is melting of ice in north Canada and on Greenland”.

“This Ring Of Ice spells danger, just like the name Ring Of Fire indicates danger”, Sam Carana concludes. “The name Ring Of Fire warns about possible volcanoes, earthquakes, landslides and tsunamis. The Ring Of Ice seems even more dangerous, since seismic activity could destabilize methane hydrates contained in sediments under the Arctic Ocean, and could trigger huge methane eruptions. The fault line running from Greenland to Siberia is the most dangerous area on Earth in that respect”.

From the earlier post High Methane Levels over Laptev Sea

Post by Sam Carana.

Sunday, September 15, 2013

Methane Release caused by Earthquakes

Methane hydrates can become destabilized due to changes in temperature or pressure, as a result of earthquakes and shockwaves accompanying them, severe storms, volcanic activity, coastal collapse and landslides. As an example, an earthquake followed by methane release was discussed in the post Sea of Okhotsk a few months back. Such events can be both primed and triggered by global warming, particularly in the Arctic, as follows:

As more ice melts away on Greenland and more water runs off into the sea, there is less weight on the Earth’s crust under Greenland. The crust and mantle can bounce back during a large melt, an effect that is called 'isostatic rebound'. This rebound can not only trigger earthquakes and landslides, it can also suck up the magma in the Earth’s crust to the surface and trigger volcanic eruptions.
The added weight of water from melting glaciers stresses the Earth’s crust underneath the sea, which can cause earthquakes. This is especially the case for coastal waters, where the impact of the water that flows into the sea is huge, not only in terms of weight, but also in terms of the currents they cause.
As the permafrost melts, mountain ranges, soil and submarine sediments all become less robust. Where the permafrost previously held things together, we can now expect more coastal collapse, avalanches and landslides, which can send shockwaves through the sea that in turn trigger earthquakes and hydrate destabilization.
Methane hydrates that are on the edge of stabilization can be disturbed by global warming in two additional ways, temperature and pressure: Warming of the Earth's crust as heat penetrates sediments on the seafloor. Thermal expansion of the Earth's crust means that the crust will expand slightly in volume, resulting in expansion of the cavity that holds the hydrates.
Finally, there's the additional impact of methane itself. Permafrost previously kept methane stable in sediments. Methane converting from hydrates into free gas will expand some 160 times in volume; this explosive process can trigger further destabilization. Once released into the atmosphere, the methane has a huge local warming potential, adding to the threat that further methane releases will occur locally.

Back in 2006, Bill McGuire said: "A particular worry is that this in turn will contribute to large-scale releases of methane gas from the solid gas hydrate deposits that are trapped in marine sediments. Gas hydrates have been identified around the margins of all the ocean basins, and outbursts of gas may occur as sea temperatures climb or as rising sea levels trigger underwater quakes in the vicinity."

For more than a decade, Malcolm Light, contributor to the Arctic-news blog, has been warning about the danger of methane hydrate destabilization due to earthquakes (see the poster at the bottom of the page on seismic activity).

With this in mind, let's take a look at the most recent picture of Earth.

September 13, 2013, 3am - Sep 14, 2013 1am [ click on image to enlarge ]

The large number of yellow spots in the top left corner are related to the flooding in the Basin of the Amur River (Heilong Jiang). Such extreme weather events are becoming ever more prominent, due to global warming and the feedbacks such as methane releases. Similarly, extreme weather events such as droughts and heatwaves lead to wildfires that also produce large amounts of methane.

The image only shows the Northern Hemisphere, but on the Southern Hemisphere, high levels of methane have been recorded for a long time on Antarctica. While huge amounts of snow fall on Antartica, the amount of snow and ice that melts each year is even larger, widening the difference between the weight the snow and ice exercize between periods. This difference in weight could similarly cause rebounds of the Earth's crust, sucking up the magma and causing methane hydrates to be destabilized, as described in the earlier post Antarctic methane peaks at 2249 ppb.

The image also shows fault lines. Several yellow spots are present on the fault line over the Arctic, including some that point at the coast of Norway; they appear to be caused by seismic activity along the fault line, as discussed in the recent post Methane reaches 2571 ppb.

Meanwhile, methane readings peaked at 2416 ppb on September 14, 2013. Very worrying are also the high methane readings close to the Gakkel Ridge, the fault line at the center of the Arctic Ocean, and the spots closer to the Laptev Sea.

Finally, there are high readings along the Aleutian Islands, Alaska. The islands, with their 57 volcanoes, are in the northern part of the Pacific Ring of Fire and they have experienced a lot of seismic activity lately, including an earthquake with a magnitude of 7 on the Richter scale on August 30, 2013, and several more recent earthquakes with a higher magnitude than 6 on the Richter scale.

[Editor: The images below, added September 24 and 26, 2013, show high methane releases at a spot just north of Greenland that was hit by an earthquake with a magnitude of 4.5 on the Richter scale on September 1, 2013, as also discussed in the post Methane reaches 2571 ppb. The two bottom images also show the magnitude 5 earthquake that hit Russia on September 24, 2013.]