Ocean Drilling: How the Past Can Provide Clues to our Planet’s Future Climate
Filed under: Discovery,News & Resources,Scientific Ocean Drilling
On a remote patch of ocean 1250 miles southwest of Hawaii, the crew of the scientific drilling ship JOIDES Resolution have lowered a massive drill bit through 3 miles of pipe to the seafloor below. By pulling cores of ancient ooze from beneath the ocean floor, scientists hope to learn how the Earth responded to climate change 50 million years ago-and how it may react to future warming. Geologist Trevor Williams from Columbia University’s Lamont-Doherty Earth Observatory reports on progress from onboard the ship.
By Trevor Williams
Published on: April 3, 2009
Popular Mechanics
Pacific Ocean, 142° W, 12° N - For the last two years the drillship JOIDES Resolution has been in the Singapore shipyards, where it was stripped right down to the hull and built back up again with the latest technology for investigating deep-sea drill cores. Altogether, I have spent nearly a year of my life on this ship, but now I hardly know my way around it-the bridge, galley and science labs all expanded or moved. While much is new, some things have not changed: The drilling derrick still rises 205 feet above the moon pool-the 23-foot-wide hole in the center of the ship through which the drill string is lowered-and the captain and crew from such far-flung places as Texas, Scotland and the Philippines are happy to be back at sea. Most important, the ship’s mission remains the same: To drill into the sediments and rocks under the seabed of the world’s oceans to reveal the secrets they hold about the Earth’s past. This is part of the Integrated Ocean Drilling Program, an international effort to record the planet’s history by plumbing its depths.
In early March, a team of scientists and technicians from around the world convened onboard for the ship’s first expedition since its retrofit. We set sail from Honolulu to a remote spot 1250 miles southwest of Hawaii, where we pulled the first 30-foot-long core of red clay from the seabed, three miles below us, two weeks ago. Beneath the clay lies 500 feet of white ooze, like toothpaste, and brown ooze, like crumbly brown sugar, all made up of the tiny shells of plankton. And beneath that lies basalt rock crystallized from lava at the mid-ocean ridge 53 million years ago. Our main targets are in the white ooze layer: tiny shells dating back to the Eocene epoch, which lasted from 54.8 to 33.7 million years ago. The chemical makeup of such shells reveals a global temperature several degrees warmer than it is today, as do alligator bones and palm tree pollen from the same period found in the arctic. In the tropics, temperatures were hot enough to support giants like the 42-foot snake whose fossil remains were unearthed in Colombia earlier this year.
While we know that the Eocene was warmer than the current climate, the sediments we are drilling will give us detailed information about the temperature extremes and how fast the climate changed. This epoch was punctuated by “hyperthermals,” short-lived events (geologically speaking) that were hotter still. The questions we are trying to answer include: What caused these hyperthermals? And how long did it take for temperatures to return to normal? Though they lived and died 50 million years ago, these plankton can ultimately help us understand how the climate system works in a greenhouse world.
Scientific ocean drilling has a long history that goes back to 1961, when Project Mohole set out from San Diego in a drilling barge funded by a team of oil companies. The project’s goal was to bore into the deep seabed off Guadalupe Island. They only reached 600 feet down, but accomplished something important in the process: They were the first to discover what the ocean crust was made of and showed that the tricky business of recovering rock cores from the deep sea could be done. John Steinbeck, author and amateur oceanographer (Sea of Cortez: A Leisurely Journal of Travel and Research is a must-read, on any oceanographer’s bookshelf) was onboard with an “elite and motley crew” of cooks, seamen, drillers, scientists and engineers. He wrote that we know less about the seabed than we do about the moon and anticipated a long-term plan to explore the two-thirds of the planet that lies beneath the sea. Since then, well over a thousand sites have been drilled throughout the world’s oceans. The successors of the original ocean drilling crew are on this ship, and they have no less wonder for deep sea cores, and the stories they hold, than the pioneers of 1961.
Trevor Williams is a geologist at the Lamont-Doherty Earth Observatory of Columbia University in New York.
