I am sometimes asked how bad climate change will get, and how fast. I don't know specifics. I can show you data, reasons for concern, and one study that claims an Arctic methane threat was greatly overrated.
However, as a reminder, President Niinistö of Finland said in a Joint Press Conference with President Trump, August 28,2017, “If we lose the Arctic, we lose the globe.”
The Economist reported today "In the past decade methane levels have shot up (see chart), to the extent that the atmosphere contains two-and-a-half times as much of the gas as it did before the Industrial Revolution. Earlier this month America’s National Oceanic and Atmospheric Administration (NOAA) confirmed another sharp rise in 2017. [ . . . .] Of [an annual] 50bn-tonne total ["of 'carbon dioxide equivalent' of heat trapping gasses], 70% is carbon dioxide itself. Half the remaining 15bn tonnes is methane. [ . . . .] The explanations put forward by scientists range from the troubling to the truly hair-raising."
As I reported before, The U. S. Geological Survey and the University of Rochester noted in a recent study the Arctic-methane issue may not be as dire as some scientists imagined. That study claims "most of the methane released by gas hydrates never reaches the atmosphere. Instead, the methane often remains in the undersea sediments, dissolves in the ocean, or is converted to carbon dioxide by microbes in the sediments or water column. [ . . . .] Professor Kessler explains that, 'Even where we do see slightly elevated emissions of methane at the sea-air interface, our research shows that this methane is rarely attributable to gas hydrate degradation.'[ . . . .] The authors’ sober, data-driven analyses and conclusions challenge the popular perception that warming climate will lead to a catastrophic release of methane to the atmosphere as a result of gas hydrate breakdown.”
The study continues, "The review pays particular attention to gas hydrates beneath the Arctic Ocean, where some studies have observed elevated rates of methane transfer between the ocean and the atmosphere. As noted by the authors, the methane being emitted to the atmosphere in the Arctic Ocean has not been directly traced to the breakdown of gas hydrate in response to recent climate change, nor as a consequence of longer-term warming since the end of the last Ice Age."
Natalia Shakhova, ("Expertise: chemical oceanography") Research Associate Professor at International Arctic Research Center at The University of Alaska Fairbanks, seems to disagree. She says in the above video, "As compared to the mid-depth of the world's ocean which is few hundred meters, up to kilometers, the East Siberian Arctic Shelf mid-depth is only 50 meters." She notes this is a problem because the more-shallow waters allow greater amounts of methane to rise into the atmosphere. The other major concern she has is quantity. She says the total amount of methane in Earth's atmosphere is "about 5 gigatonnes. The amount of carbon preserved in form of methane in the East Siberian Arctic Shelf is approximately from hundreds to thousands of gigatonnes. And, of course, it's only 1% of that amount is required to double the atmospheric burden of methane."
As a reminder, an October 4, 2016, Siberian Times article quoted Professor Igor Semiletov, of Tomsk Polytechnic University, Shakhova's colleague speaking in the above video. Semiletov said "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 [ . . . ] many thousands of times. If 3-4% from underwater will 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. This is due to the fact that the greenhouse effect of one molecule of methane is 20-30 times greater than one molecule of CO2."
The good news is that even though methane has a much stronger effect than CO2, the life of methane in the atmosphere is shorter. Duncan Clark's January 16, 2012 article in The Guardian noted "Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years" while "Methane, by contrast, is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years."
In other words, depending on how much Arctic methane is released how fast, it could be a difficult time for humans and other species if Shakhova's and Semiletov's concerns become reality. Creon says in the Greek tragedy Oedipus "Time is the one incorruptible judge."