There are scientists floating in the middle of the North Atlantic who are holding the dinosaur extinction in their hands. Really. Here it is:
This may look like an alien landscape, but it’s actually a section of deep sea mud from the drilling ship Joides Resolution. When the lighter-toned sediment on the left was deposited, there were dinosaurs and happy marine plankton – the light color is from calcium carbonate shells. The dark grey-black is stuff thrown up by the meteor. Then, in the dark red, there were no dinosaurs, and much less marine plankton with shells. (See the scientists explain it in video here). That’s the idea behind bringing up cores of mud from the deep sea – there’s history in that there mud.
Since one of the co-chief scientists is Scripps professor Dick Norris (when I took his classes, I was really sad that I had not become a geologist!), the education officer Caitlin Scully offered Deep Sea News a behind-the-scenes look at the ‘s current expedition. While they were pretty excited about finding the dinosaur extinction, they’re primarily interested what came right afterwards. Caitlin writes:
Finding K-T boundary core was one of the most exciting moment’s we’ve had so far! It was perfect. We could see a layer of blackish-green gritty material that the asteroid impact ejected into the atmosphere, which then rained down into the ocean. There was an abrupt change from light grayish sediment, rich in the white calcium carbonate shells of fossil plankton, to brown sediment devoid of calcium carbonate plankton fossils. Many members of our science party posed for pictures with the K-T, our very own celebrity sediment core. Even though the K-T core was amazing, our primary objective is to learn about the climate events that occurred after 65 million years ago.
Our first drilling location was located in about 5 km of water and we brought sediment onboard that recorded nearly 80 million years of Earth’s past. In one hole we had a record of everything from the K-T Boundary, the Paleocene-Eocene Thermal Maximum, the ELMO, the E-O boundary and records of many smaller climate events. It was if we opened an earth history textbook and made a checklist of important climate events to find – they were all preserved in 300 meters of North Atlantic Sediment. One member of the science party described our cores as a “Box Set of the Greatest Hits of Earth’s Climate Past.”
Expedition 342 is drilling into the past to learn about the future. Our expedition focuses on a time called the Paleogene, which lasted from about 65 to 21 million years ago. During the early Paleogene, Earth’s temperatures were considerably warmer than today and supported swampy forests rather than ice sheets at the poles. The sediment cores we recover will create a detailed reconstruction of ocean chemistry, circulation, and history of this time period. The Paleogene greenhouse world represents a climatic state that the Earth is rapidly re-approaching due to the use of fossil fuels and the subsequent release of atmospheric greenhouse gases. Expedition 342 sets out to answer key questions about the Paleogene such as: How did the climate and ecosystems of the Paleogene world work? What should we expect in the next century? Although the early Paleogene is not a perfect analogue for the future, uncovering the story of past climate change will help us understand what the future holds for our rapidly warming planet.
This climate shift can actually be seen in the cores as well. Again, the color change is caused by a mass extinction event, this time of marine plankton organisms called foraminifera. [UPDATE: Simon D. says that this color change is not actually caused by foraminifera: “The color change is most likely caused by an increase in the clay/carbonate ratio in the sediments (we’ll have to wait for the data to be really sure). This is caused by either an increase in clay supply to the deep sea (due to increases erosion of the hinterland and transport) or a reduction in the amount of carbonate because of dissolution (shallowing of the lysocline/CCD)…the PETM is characterized by a severe (yet partial) extinction of deep-sea benthic foraminifera, not the planktics as you state.”]