A thorough read through the numerous SWERUS-C3 blog posts since the major methane flare find will reveal snippets of more methane discovered, there are mentions of finding some methane release in anticipated areas expected and GoFlo sampling where the saturation was high enough. However, it does not seem another major hot spot has yet been found, given the struggle with ice, and lower water temperatures, including at the sea bottom in the East Siberian Sea (ESS). You can read the expedition blogs at: http://swerus-c3.geo.su.se/index.php/swerus-media
While my primary interest is Arctic methane sources and release, something far more troubling has been found. Here is the "norm" and then the trouble.
The Arctic Ocean: A CO2 Sink
Generally, the cold ice-bound Arctic Ocean is viewed as a carbon sink, the water absorbing CO2 from the atmosphere, with its acidity increasing through time. That is a real concern for sea life, and generally been presumed a way that CO2 would be transferred from the atmosphere and slow warming. This process was documented in research across the Arctic Ocean and was the topic of a conference in May, 2013.
An AFP article stated the following:
"Acidity levels in the planet’s oceans have risen by 30 percent since the start of the
industrial era, and are now at their highest levels in at least 55 million years, delegates
said at a conference in Bergen, Norway dedicated to the subject.
Furthermore, the increase in melting ice exposes greater expanses of water, which leads to greater absorption.
In the Iceland and Barents seas, pH levels have decreased by around 0.02 per decade since the end of the 1960s.
Even if carbon dioxide emissions were to be brought to a halt today, it would take tens of thousands of years for the oceans to return to the acidity levels they had before the industrial era began two centuries ago, according to Norwegian researcher Richard Bellerby, the main author of a scientific study on the subject."
Source: Scientists sound alarm at Arctic Ocean's rapid acidification, Agence France Presse, Monday 6 May 2013, http://www.arabnews.com/news/450644
See also: "The Arctic Ocean marine carbon cycle: evaluation of air-sea CO2
exchanges, ocean acidification impacts and potential feedbacks", Biogeosciences, November 5, 2009. http://www.biogeosciences.net/6/2433/2009/bg-6-2433-2009.pdf
The Arctic Ocean: CO2 Sink - and Source
However, a study by MIT gave a more refined perspective of the Arctic Ocean as carbon sink, and ever increasing acidificatio.
What their research revealed was that during 2005 through 2007, and continuing in areas like the Barents Sea, as ocean water warmed, it began to absorb less CO2 - and then began to release it.
The paper by Stephanie Dutkiewicz and co-authors Mick Follows and Christopher Hill of MIT, Manfredi Manizza of the Scripps Institute of Oceanography, and Dimitris Menemenlis of NASA's Jet Propulsion Laboratory, published in the journal Global Biogeochemical Cycles. demonstrated this finding.
"Manizza found a discrepancy between 2005 and 2007, the most severe periods of sea ice shrinkage (at that time). While the Arctic lost more ice cover in 2007 than in 2005, less carbon was taken up by the ocean in 2007 -- an unexpected finding, in light of the theory that less sea ice leads to more carbon stored.
"Manizza traced the discrepancy to the Greenland and Barents seas, regions of the Arctic Ocean that take in warmer waters from the Atlantic. (In warmer environments, carbon is less soluble in seawater.) Manizza observed this scenario in the Barents Sea in 2007, when warmer temperatures caused more carbon dioxide to be released than stored."
The Arctic Ocean: An Increasing CO2 Source?
While Manizza discovered that warmer water in the Barents Sea led to release of CO2 - the Arctic Ocean becoming a source of emissions, this has not been recognized, or accepted by other scholars who assume that the additional open ocean will increase the ability of the Arctic Ocean to absorb CO2, and increasing acidity over time.
However, there seems to be some data that might illustrate the Arctic potential as a CO2 source may be increasing. For example, during June through September, 2013 O-Buoy #7 recorded CO2 of almost 480 ppm. the following is the CO2 readings from June 3 to July 3, 2013.
Here is the longer trend - about 6 months of data with readings above 400 ppm well into September, 2013.
The Arctic Ocean: An Increasing CO2 Source: SWERUS-C3
Finally, we return to SWERUS-C3 expedition. Professor Leif Anderson, a marine chemist at the University of Gothenburg submitted the following on his blog on July 28, 2014. While he comments on the methane release he notes the fact that the Laptev Sea is acting as a CO2 source, and that thawing permafrost on the shallow sea floor was the cause. The map above will help give a visual for what follows, (caution: auto-translation to English):
"With five stations on two days there was a total of approximately 100 samples that we analyzed in order to evaluate the water masses flowing along the slope between the shallow Laptev Sea and the deep basin. When this work was finished, we sailed towards the east during the time that we stopped a few times for stations at about 50 meters depth." (the area circled above)
"Now begins the interesting things happen with the chemistry. The oxygen concentration becomes low, near the ground (sea floor), a clear signal to the decomposition of organic materials. This also means that the carbon dioxide concentration is high. The most surprising is that the carbon dioxide concentration is also high in the surface water, so high that it is above the equilibrium level of the atmosphere. Thus carbon dioxide is leaking out of the sea in this area. Normally the sea under-saturated during the summer when växtpankton (plankton) bloom. The reason that it is over saturated is probably due to the supply of organic matter from land that is broken down to a greater extent than the phytoplankton bloom. This was something we observed during an expedition to the sea in 2008, but in areas closer to shore than where we are now."
What makes this intriguing - and troubling, is that the charted path of SWERUS_C3 is no where near land, this is not likely decaying debris washed out to sea. the course seems to be what is thawing on or under the sea floor itself.
While we have concerns about CH4 leaking from the East Siberian and Laptev shelves, we may have to also contend with the longer term impacts of increased CO2 release. A glance at the Metop 1-B July 27 and 28, 2014, 0-12 hours imagery provides a hint of the increased carbon dioxide readings in the Arctic Ocean when this report was prepared by Dr. Anderson. By displaying images for 972 mb, we are portraying CO2 concentrations close to the sea surface.
Source: NOAA/OSPO IASI imagery: http://www.ospo.noaa.gov/Products/atmosphere/soundings/iasi/index.html