In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold.
https://serc.si.edu/media/press-release ... obal-scope
In the past 50 years, the amount of water in the open ocean with zero oxygen has gone up more than fourfold.
As noted above, Ward’s work focused on causes and what he found at numerous dig sites around the world was evidence of a ‘Great Dying’ that began at the ocean floor, proceeded upward from the depths, and eventually came to transcend the ocean boundary and inflict a similar, if less pronounced, lethality upon terrestrial organisms. The mechanism Ward proposed for the worst extinction in Earth’s geological memory involved how oceans and, in particular, living creatures in the oceans, respond to rapid warming. Ward found that during periods of high heat called hothouse states, oceans first became anoxic and stratified and then, during the worst events, transitioned to a deadly primordial state called a Canfield Ocean.
This graphic shows how methane, a greenhouse gas, boosts the abundance of water at the top of Earth's atmosphere. This water freezes around "meteor smoke" to form icy noctilucent clouds, or NLCs.
Alfred Tennyson wrote:We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield.
Tanada wrote:
November 2017: 1860.1 ppb
November 2016: 1851.2 ppb
However, scientists report a sudden surge in global methane emissions in the last three years, 2014-16.
onlooker wrote:https://m.phys.org/news/2017-04-early-out-of-control-climate.htmlHowever, scientists report a sudden surge in global methane emissions in the last three years, 2014-16.
ROCKMAN wrote:d - Yes, a 2C warming will probably have little effect on the release of methane from the clathrates. ....
"Methane clathrates in continental rocks are trapped in beds of sandstone or siltstone at depths of less than 800 m. .....And obviously deep marine clathrates will be even less effected by a 2C increase in atmospheric temp increases.
Dr. Shakhova: As we showed in our articles, in the ESAS, in some places, subsea permafrost is reaching the thaw point. In other areas it could have reached this point already. And what can happen then? The most important consequence could be in terms of growing methane emissions… a linear trend becomes exponential.
This edge between it being linear and becoming exponential is very fine and lays between frozen and thawed states of subsea permafrost. This is what we call the turning point. To me, I cannot take the responsibility in saying there is a right point between the linear and exponential yet, but following the logic of our investigation and all the evidence that we accumulated so far, it makes me think that we are very near this point. And in this particular point, each year matters.
Gas in the areas of hotspots is releasing from the seabed deposits, in which free gas has accumulated for hundreds of thousands, or even for a million years. This is why the amount of this gas and its power in releasing (due to its high pressure) is tremendous.
Dr. Shakhova: The importance of hydrates involvement in methane emissions is overestimated. The hydrate is just one form of possible reservoirs, in which pre-formed methane could be preserved in the seabed if there are proper pressure/temperature conditions; it is just the layer of hydrates composes just few hundred of meters – this is a very small fraction compared to thousands of meters of underlying gas-charged sediments in the ESAS.
Dr. Semiletov added that the 5 billion tonnes of methane that is currently in the Earth’s atmosphere represents about one percent of the frozen methane hydrate store in the East Siberian Arctic Shelf. He finishes emphasising “…but we believe the hydrate pool is only a tiny fraction of the total.”
Dr. Shakhova: The second point is that the hydrates are not all of the gaseous pool that is preserved in this huge reservoir. This huge area is 2 million square kilometres. The depth of this sedimentary drape is a few kilometres, up to 20 kilometres at places. Generally speaking, it makes no difference if gas releases from decaying hydrates or from other free-gas deposits, because in the latter, gas also has accumulated for a long time without changing the volume of the reservoir; for that reason, gas became over pressurised too.
Unlike hydrates, this gas is preserved free; it is a pre-formed gas, ready to go. Over pressured, accumulated, looking for the pathway to go upwards.
In our observations, we have accumulated the evidence that this gas front is propagating in the sediments. To me as a scientist, these points are enough to be convinced that methane release in the ESAS is related to disintegration of subsea permafrost and associated destabilisation of seabed deposits whether it is hydrates or free gas accumulations.
There is no mechanism to stop permafrost disintegration in the ESAS besides shelf exposure above the sea level that would serve to freeze the gas migration paths so that they integrate with the permafrost. Before that, the amount of methane that is releasing will increase while the supply lasts.
As gas within the sedimentary basins of the ESAS have been accumulating for a million years with no way to be released earlier, the supply for currently occurring emissions is tremendous. Because the shelf area is very shallow (mean depth is less than 50 metres), a fraction of these emissions will reach the atmosphere. The problem is that this fraction would be enough to alter the climate on our planet drastically.
Dr. Shakhova: As we showed in our articles, in the ESAS, in some places, subsea permafrost is reaching the thaw point. In other areas it could have reached this point already. And what can happen then? The most important consequence could be in terms of growing methane emissions… a linear trend becomes exponential.
This edge between it being linear and becoming exponential is very fine and lays between frozen and thawed states of subsea permafrost. This is what we call the turning point. To me, I cannot take the responsibility in saying there is a right point between the linear and exponential yet, but following the logic of our investigation and all the evidence that we accumulated so far, it makes me think that we are very near this point. And in this particular point, each year matters.
onlooker wrote:Actually, I would be interested in knowing Dissident's opinion on the Semiletov and Shakhova paper! And the conclusions Cid Yama reaches from it
New expedition in Laptev Sea suggests increase in the rate of underwater permafrost degradation.
'The area of spread of methane mega-emissions has significantly increased in comparison with the data obtained in the period from 2011 to 2014,' Semiletov said. 'These observations may indicate that the rate of degradation of underwater permafrost has increased.'
Five years ago Semiletov reported:
'We found more than 100 fountains, some more than a kilometre across....These are methane fields on a scale not seen before. The emissions went directly into the atmosphere... Earlier we found torch or fountain-like structures like this...
This is the first time that we've found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It's amazing. Over a relatively small area, we found more than 100, but over a wider area, there should be thousands of them.'
'We have reason to believe that such emissions may change the climate. This is due to the fact that the reserves of methane under the submarine permafrost exceed the methane content in the atmosphere is many thousands of times.
'If 3-4% from underwater go into the atmosphere within 10 years, the methane concentration therein (in the atmosphere) will increase by tens to hundreds of times, and this can lead to rapid climate warming."
The new expedition was organised by the Laboratory of Arctic Research in Pacific Oceanology Institute of the Far Eastern Branch of Russian Academy of Sciences in cooperation with Tomsk Polytechnic University (TPU), the Institute of Oceanology of the Russian Academy of Sciences, Institute of Atmospheric Physics, Russian Academy of Sciences, and was funded by the Russian Government and the Russian Science Foundation.
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