Methane reaches 2571 ppb

Methane as recorded by IASI* reached levels of up to 2571 parts per billion (ppb) on September 11, 2013.

The image below shows the peak levels that have been reached recently, as well as the highest mean methane level for each day.

Where did the methane come from?

IASI data do not identify locations, other than that all locations where methane is present in concentrations higher than 1950 ppb show up in yellow.

Yet, there are some ways to further examine where these high levels came from. To create the top image, only four layers were selected. The yellow spots on the image show locations where methane is present at the selected layers (695-766 mb) at concentrations of 1950 ppb and higher. At these relatively low altitudes, yellow spots will show up at fewer locations than at some of the higher altitudes, yet one can assume that the largest sources will be included among those showing up; and indeed, peak methane levels at these altitudes ranged from 2193 ppb to 2328 ppb, which are extremely high levels.

On the top image, there are several locations that look suspicious, including a large spot north of the New Siberian Islands, while the Kara Sea and the Barents Sea, and many locations around Greenland all feature suspicious yellow spots.

Most worrying are the numerous spots clustered off the coast of Norway, which show up quite prominently at many altitudes. The situation is reminiscent of the Storegga Slides, the underwater landslides that occurred at the edge of Norway's continental shelf thousands of years ago. The latest incident occurred some 8,000 years ago.

Seismic Activity

Earthquakes can cause tremors over long distances, especially along fault lines.

There has been some seismic activity close to Greenland that could have triggered one or more landslides off the cost of Norway, since the fault line points that way. An earthquake with a magnitude of 4.5 on the Richter scale occurred occured on September 1, 2013, 08:49:19 UTC, at a location 214km NE of Nord, Greenland, as illustrated by above image and the image below.

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* IASI (Infrared Atmospheric Sounding Interferometer) is a hyperspectral infrared sounder residing on the European Space Agencys (ESA) MetOp series of polar orbiting satellites.

Methane levels keep rising rapidly

Global methane levels keep rising rapidly. Earlier this month, the post Methane as high as 2303 ppb quickly became outdated and was updated with the post Methane as high as 2349 ppb. Meanwhile, though, the most recent data show that the highest level reached on August 5, 2013, was 2442 ppb.

This recent peak level is only slightly below the highest peak level this year, which was a level of 2475 ppb reached on April 26, 2013, which at the time was considered a one-off local peak.

These recent high peak levels do seem to be more than just local peaks, given that high levels of methane are suddenly recorded over much of the globe, as described in the earlier post Methane as high as 2349 ppb.

The image on the right (added later, editor) also shows that not only have peak levels greater than 2300 ppb appeared since late June 2013, but also have the highest daily mean methane levels suddenly increased by about 20 ppb recently.

The image below shows over how many square kilometers methane was present at over 1950 ppb globally over the past few days.

The numbers also feature in the image on the left and they illustrate the huge jump that took place somewhere between July 31 and August 1, 2013.

It may be that there has indeed been a huge sudden increase in methane.

On the other hand, it could also be that EuMetSat implemented a re-calibration on July 31. After all, EuMetSat announced recently that IASI Level 2 products from Metop-B had been declared operational and would be available on GTS from 31 July.

Such a re-calibration (if it did indeed take place) does appear to make sense, given the discrepancy between IASI's mean methane levels and the levels recorded at stations. Below are measurements taken at Mauna Loa, Hawaii, which given the station's location close to the equator are often taken as global averages (flasks on the left, and hourly average in situ measurements on the right).

[ click on image to enlarge ]
from: http://www.esrl.noaa.gov/gmd/dv/iadv/index.php

Mauna Loa methane levels are often quoted to be about 1830 ppb, whereas the highest IASI mean levels did barely cross the 1800 ppb mark earlier this year. Since the jump, the highest IASI mean levels have suddenly been significantly higher (20 ppb more, at around 1820 ppb).

Even so, the current situation is very worrying. High levels of methane are present not only on the Northern Hemisphere, but also on Antarctica and over the oceans on the Southern Hemisphere, as shown in a recent post. And of course, the situation remains most threatening in the East Siberian Arctic Shelf (ESAS), as described at the Methane-hydrates blog and and at Arctic Methane FAQ.