Geologist Uses Archaeology To Understand Climate Change (Transcript) | WAMU 88.5 - American University Radio

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Geologist Uses Archaeology To Understand Climate Change

MS. REBECCA SHEIR

00:00:03
Okay, so now we're going to step way further back in time for a story about our prehistoric past and what it may be telling us about our future. Sabri Ben-Achour has the story.

MR. SABRI BEN-ACHOUR

00:00:15
The history of the past 100 million years is in a box in David Powars' home office in Winchester, Va. Powars is a geologist with the U.S. Geological Survey. So it kind of makes sense that his home office is basically an archeological site in and of itself. There are piles 6 feet high of maps and papers and boxes, fist-size drill bits.

MR. SABRI BEN-ACHOUR

00:00:35
He pulls out cylinders of rock and clay he drilled a few miles south of D.C.

DR. DAVID POWARS

00:00:39
Right here on the Potomac River.

BEN-ACHOUR

00:00:41
The cylinders are samples of the bedrock from hundreds of feet below, so you can see all the layers of soil, mud, and rock from ages past. And these ones are mostly blackish green.

POWARS

00:00:50
This green sand.

BEN-ACHOUR

00:00:55
Powars can read this record like a book but instead of words, he sees microscopic fossils and layers of minerals and 55 million-year-old-poop.

POWARS

00:01:03
Why it's called a green sand is these tiny little feces from the bugs that were living in it, that are little black and green minerals.

BEN-ACHOUR

00:01:11
From looking at that old, poopy clay and the fossils inside Powars can tell that 60 million years ago the D.C. area was a calm, shallow sea where microscopic bugs could live their little bug lives gently swimming and pooping in peace. And then, 55 million years ago...

POWARS

00:01:28
Everything changed.

BEN-ACHOUR

00:01:30
In the geological blink of an eye, the Earth totally changed and you can be seen in Powars' rock sample.

POWARS

00:01:36
All of a sudden dramatically, bang, we go into this Kalinic rich clay.

BEN-ACHOUR

00:01:40
The next layer in his rock sample is cream colored because all those happy green pooping bugs are gone.

POWARS

00:01:46
All the bugs are missing.

BEN-ACHOUR

00:01:47
All the shell fossils that were in the layer before are gone too, they've gone extinct.

POWARS

00:01:52
The sedimentation rate during this short period, it increased ten-fold.

BEN-ACHOUR

00:01:57
This bizarre new Earth is home to a lot of rain and a ton of massive storms. Mega rivers form between the Potomac and the Susquehanna and dump huge amounts of mud into the calm sea we used to have.

POWARS

00:02:09
This was a big river-dominated shelf and it's like the Amazon. You got this big river that's just dumping out there and that's what these sediments tell us.

BEN-ACHOUR

00:02:18
The Washington region, according these rocks, looked like the Amazon.

POWARS

00:02:22
Something had to happen dramatic to do that.

BEN-ACHOUR

00:02:24
What happened was climate change. In fossils all over the planet from this time, the carbon changes. Massive amounts of carbon entered the atmosphere and the oceans and the greenhouse effect intensified.

POWARS

00:02:35
We had this major thermal maximum, the hottest time we know of and it came on very fast. It had worldwide effects on the climate and the oceans. It killed off a lot of stuff in the oceans.

BEN-ACHOUR

00:02:48
How hot did it get?

POWARS

00:02:50
So all of a sudden tropical fauna will be found and flora will be found up in the Arctic. Crocodiles, palm trees, rhinoceros.

BEN-ACHOUR

00:03:00
The Earth's temperature rose 40 degrees Fahrenheit.

POWARS

00:03:03
The shoreline was some place west of Richmond, west of D.C., some place on the Piedmont. We've just dated marine sediments west of Richmond and it rose another 10, 20 meters it's calculated. Some like to say five meters but even five meters in a short time would be a lot.

BEN-ACHOUR

00:03:20
Nobody knows where the carbon that caused this change came from, could've volcanoes, could've been escaping gases. But scientists were able to calculate how much of it was released. Lee Kump is a professor of geosciences at Penn State University.

MR. LEE KUMP

00:03:35
The total quantity of carbon added to the atmosphere was something on the order of the quantity of carbon that we have in known fossil fuel reserves today.

BEN-ACHOUR

00:03:47
So are we headed toward a future in which the Blue Ridge Mountains are ocean front property? Gavin Schmidt is a climate scientist at the NASA Goddard Institute for Space Studies. He says it's hard to say because the world 55 million years ago was pretty different to begin with.

MR. GAVIN SCHMIDT

00:04:00
There was no ice around, it was a very different base climate. So there was no huge continent of Antarctica covered in ice, there was no Greenland ice sheet. And so a lot of the things that we're worried about going into the future, going into this next century are associated with features that are kind unique to this climate.

BEN-ACHOUR

00:04:19
Another difference, the thermal maximum carbon release took 20,000 years and the super warm period lasted 170,000 years. Humans could easily burn up all their fossil fuels in a couple hundred years and Lee Kump says in this case, speed matters.

KUMP

00:04:35
The temperature rise, again, in the worst case scenario could be comparable to this extreme warming event in Earth history but even more critical here is that the rate of change is maybe a factor of ten faster.

BEN-ACHOUR

00:04:49
There's a big difference between having 20,000 years to adapt to something versus having just a few hundred. I'm Sabri Ben-Achour.
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