PETM Started as Mild Warming, Went Overboard

(image credit: National Geographic)

What started out as a moderate global warm-up about 55 million years ago triggered a massive injection of greenhouse gases into the atmosphere that sent temperatures skyrocketing, a new study says.

The finding suggests that today's temperature rise may just be priming the planet for a carbon belch of epic proportions.

[...]

Sluijs and his colleagues found evidence for the chain reaction in two sections of sediment that accumulated on an ocean floor in what is now New Jersey.

The abundance and distribution of marine algae indicate the environment started to change and the ocean surface began to warm several thousand years before the large temperature spike.

The finding implies that the earlier warming triggered the injection of greenhouse gases visible in the geological record around 55 million years ago.

[...]

Scientists have long studied the ancient temperature spike, called the Paleocene-Eocene thermal maximum or PETM, for clues to what could happen as a result of today's global warming.

Research shows that during the PETM, global temperature shot up at least 9 degrees Fahrenheit (5 degrees Celsius), and swamp forests with redwoods and broad-leaved trees filled the Arctic.

[...]

One theory is that the meltdown of methane hydrates—icelike deposits that store massive amounts of potent greenhouse gases in the seafloor—was responsible.

According to the new study, pre-warming triggered the melt, releasing greenhouse gases into the atmosphere. Less clear is the nature of that pre-warming, study author Sluijs said.

One possibility, he pointed out, is a bout of volcanic activity that ripped Greenland from Europe, a theory proposed earlier this year in the journal Science.

A couple things to keep in mind: The PETM was significantly warmer than now at the start of the postulated methane hydrate release. With the spike it did do, it didn't cause more than a 'minor' mass extinction. It wasn't pleasant, but it wasn't a near life destroying threat that is now played up about glboal warming. Don't get me wrong, there will probably be extinctions from our bout of GW, but it won't be the end of the world nor will stopping it 'save the planet.' (related past post: Some bits on the Eocene Ocean & PETM Extinction)

Oh, it'll suck, to be sure, to be in Central Asia, the American SW, New Orleans, or the Mediterranean...or Australia...or Africa. However, my point is, that life will survive and so long as we are mitigate this we can do just fine. Gonna be pretty bad for China too though. What are they going to do when the Gobi or Ordos reaches Beijing?

(image credit: Maps of China, Ditu 地图)

Then again, they might have other problems.