What Environmental Reporting Leaves Out

[GliderGuider]

53. I'm not clear on something

Are you saying there's no plausible argument for such shifts having happened in the past, or no plausible argument that developments from current conditions could cause them in the near or medium term future?

There's certainly evidence that they've happened in the past:
http://www.ncdc.noaa.gov/paleo/abrupt/data4.html

The end of the Younger Dryas, about 11,500 years ago, was particularly abrupt. In Greenland, temperatures rose 10° C (18° F) in a decade (Figure 6; Cuffey and Clow, 1997).

I also notice the inclusion of the qualifier "plausible" in your assertion. "Plausible" to whom? To you? To SkepticalScience? There are certainly arguments that appear plausible to me. Like the clathrate gun hypothesis:

http://en.wikipedia.org/wiki/Clathrate_gun_hypothesis

The clathrate gun hypothesis is the popular name given to the hypothesis that rises in sea temperatures (and/or falls in sea level) can trigger the sudden release of methane from methane clathrate compounds buried in seabeds and permafrost which, because the methane itself is a powerful greenhouse gas, leads to further temperature rise and further methane clathrate destabilization – in effect initiating a runaway process as irreversible, once started, as the firing of a gun.

AKA the Methane Bomb:
http://www.climatecentral.org/news/scientists-defending-against-the-methane-bomb

In a worst-case scenario, suggest Joshuah Stolaroff, Lawrence Livermore National Laboratory, and his co-authors, with huge plumes of methane erupting into the atmosphere from underground, scientists might have to battle the gas with bombs, and more. “If the concentration of methane is high enough . . . ” they write, “. . . then a laser can be used as a remote ignition source.”

This worst-case scenario is by no means certain, but it’s certainly plausible. Scientists know that enormous reserves of methane — rivaling the world’s known reserves of fossil fuels — are buried in the permafrost and along the continental shelf surrounding the Arctic Ocean, trapped in ice formations known as methane hydrates. If the water warms enough, the gas could escape relatively quickly to add it’s planet-warming power to the greenhouse gases that are already there. This is probably what happened during a rapid warming episode known as the Paleocene-Eocene Thermal Maximum, about 55 million years ago. The temperature shot up by about 11° F at the time, causing mass extinctions of species, among other effects.

And there's evidence that it's happening:
http://www.climatecentral.org/news/scientists-close-in-on-the-cause-of-arctic-methane-leaks-15090

The first thing they found seemed reassuring: carbonate minerals created by interactions with the methane and surrounding material. If the methane came from the breakdown of hydrates, the minerals would be young, since the seafloor has only warmed recently. But they weren’t.

But they also found that the mineral byproducts of methane leakage came in concentrated pockets at different depths. If methane were coming out steadily from some reservoir deep under the sea floor, the minerals should become gradually more abundant the deeper you look.

Beyond that, scientists already know that methane hydrates are present in this area. It would be quite a coincidence, Berndt said, to find methane emissions in a place where the water is warming and where there are known hydrate deposits — and to have those three things be completely unrelated.

One possible explanation; Berndt thinks that two things may be going on at once: a slow leak of methane that’s been going on for hundreds of years, and also the beginning of the hydrate breakup that scientists have been worried about.

It seems all too plausible to me...