News / Science & Technology

Ocean Floor Reveals Past Climate Changes

For geologists, it's the equivalent of a tape recorder

Millions of years of history, which can be found on the ocean floor, are collected and analyzed at the Core Repository in New York.
Millions of years of history, which can be found on the ocean floor, are collected and analyzed at the Core Repository in New York.

Multimedia

Audio

As the earth’s climate changes, one tool for understanding its environmental impacts is the study of past climate changes, revealed by layers of sediment scientists take from the sea floor.

At the Lamont-Doherty Earth Observatory in Palisades, New York, frozen samples of those sediments are housed in a facility called the Core Repository.

Time capsule

Lamont research professor Maureen Raymo, the director of the Core Repository, slides open a long, narrow drawer from the cabinet. Like thousands of others here, the drawer contains a long, thin cylinder of layered sediment.

Core Repository Director Maureen Raymo pulls out a sea sediment sample, one of thousands at the archive.
Core Repository Director Maureen Raymo pulls out a sea sediment sample, one of thousands at the archive.

It’s a sample extracted from the ocean floor and below. According to Raymo, the cylinder’s distinctive stripes of varied colors and widths are a unique visual record, a sort of vertical time capsule.

“Imagine you are out on a boat, and you could see right through the four kilometers of water that is between you and the bottom. And on the bottom all the little fossils, all the little plankton that die over the years in the water column, their remains settled to the sea floor, just gently settled to the bottom," Raymo says. "And they accumulate, layer by layer by layer, over millions of years. So imagine you just came along and just stuck a big piston tube into the sediment, or took a straw and stuck it into the sediment and pushed it 20 meters down and extracted it, you would have a long core that would essentially be a record of sedimentation going back in time. For geologists, it’s the equivalent of a tape recorder.”

Invaluable resource

Lamont-Doherty oceanographic vessels started collecting these samples more than 50 years ago, at a time when no one was sure what they would be used for.

Core sample labels identify the exact spot on the sea floor where the sample was taken. Slight variations in location can make a significant difference in the chemical and biological composition of the sediment sample.
Core sample labels identify the exact spot on the sea floor where the sample was taken. Slight variations in location can make a significant difference in the chemical and biological composition of the sediment sample.

“The first director, Maurice Ewing, had the sense that these cores had to contain important information and it turns out they do," Raymo says. "They’ve been an invaluable resource in studying past climate change, past ocean circulation, past ocean temperatures, the evolution of life in the ocean in the past, and they are an incredible archive of the evolution of life in the ocean in the past.”

The core samples provide a reliable record partly because the deep ocean is a very peaceful place, compared to the shoreline.   

“It’s very far away from the margins where there is a lot of erosional material coming in, where there are lots of waves breaking on the shores and on the continental shelf. Material that settles through the water column just gently layers on the bottom, layer by layer by layer, and it can just be undisturbed for millions of years.”

Vital clues

According to Raymo, the types of species one finds along a length of core reveal vital clues about past environmental changes where the sample was taken. She asks us to imagine a core sample from the middle of the North Atlantic Ocean:

“And you go down your core and you see these kind of sub-polar species, temperate species. Then all of a sudden, you see species that only live in sea ice or next to sea ice.  And that tells you that at that location, at that time in the past, sea ice covered that part of the North Atlantic. Because you only see these polar species of plankton. You could go further south and look at a core and see it varying between tropical species and subtropical species, and that’s directly reflective of how the sea surface temperature was changing through time.”

Looking at climate changes of the past helps scientists understand the changes the earth is undergoing today, and is nearly certain to experience at an accelerated rate in the future. Raymo says that when she was a doctoral student in the 1980s, climate change was an esoteric subject few considered relevant.  

“And now it’s obviously incredibly relevant. Humans are changing the atmosphere in profound ways by increasing greenhouse gases, and climate is responding to that. The earth is warming. And so there are a lot of questions about how high can CO2 go without causing fairly devastating changes in global climate, either through sea level rise as ice sheets melt, changing precipitation patterns.... And the people in my field, we really look it at as ‘the past is the key to the future’ here.”

You May Like

US Imposes Sanctions on Alleged Honduran Drug Gang

Treasury department alleges Los Valles group is responsible for smuggling tens of thousands of kilograms of cocaine into US each month More

At 91, Marvel Creator Stan Lee Continues to Expand his Universe

Company's chief emeritus hopes to interest new generation of children in superheroes of all shapes and sizes by publishing content across multiple media platforms More

Photogallery New Drug Protects Against Virus in Ebola Family

Study by researchers at University of Texas Medical Branch, Tekmira Pharmaceuticals is first looking at drug's effectiveness after onset of symptoms More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
African Media Tries to Educate Public About Ebolai
X
George Putic
August 20, 2014 8:57 PM
While the Ebola epidemic continues to claim lives in West Africa, information technology specialists, together with radio and TV reporters, are battling misinformation and prejudice about the disease - using social media to educate the public about the deadly virus. VOA’s George Putic has more.
Video

Video African Media Tries to Educate Public About Ebola

While the Ebola epidemic continues to claim lives in West Africa, information technology specialists, together with radio and TV reporters, are battling misinformation and prejudice about the disease - using social media to educate the public about the deadly virus. VOA’s George Putic has more.
Video

Video Ferguson Calls For Justice as Anger, Violence Grips Community

Violence, anger and frustration continue to grip the small St. Louis suburb of Ferguson, Missouri. Protests broke out after a white police officer fatally shot an unarmed black teenager on August 9. The case has sparked outrage around the nation and prompted the White House to send U.S. Attorney Eric Holder to the small community of just over 20,000 people. VOA’s Mary Alice Salinas has more from Ferguson.
Video

Video Beheading Of US Journalist Breeds Outrage

U.S. and British authorities have launched an investigation into an Islamic State video showing the beheading of kidnapped American journalist James Foley by a militant with a British accent. The extremist group, which posted the video on the Internet Tuesday, said the murder was revenge for U.S. airstrikes on militant positions in Iraq - and has threatened to execute another American journalist it is holding. Henry Ridgwell has more from London.
Video

Video Family Robots - The Next Big Thing?

Robots that can help us with daily chores like cooking and cleaning are a long way off, but automatons that serve as family companions may be much closer. Researchers in the United States, France, Japan and other countries are racing to build robots that can entertain and perform some simpler tasks for us. VOA’s George Putic reports.
Video

Video In Ukraine, Fear and Distrust Remain Where Fighting has Stopped

As the Ukrainian military reclaims control of eastern cities from pro-Russian separatists, residents are getting a chance to rebuild their lives. VOA's Gabe Joselow reports from the town of Kramatorsk in Donetsk province, where a sense of fear is still in the air, and distrust of the government in Kyiv still runs deep.
Video

Video Five Patients Given Experimental Ebola Drug Said to Be Improving

The World Health Organization has approved the use of experimental treatments for Ebola patients in West Africa. The Ebola outbreak there is unprecedented, the disease deadly. The number of people who have died from Ebola has surpassed 1,200. VOA's Carol Pearson reports on the ethical considerations of allowing experimental drugs to be used.
Video

Video China Targets Overseas Assets of Corrupt Officials

As China presses forward with its anti-graft effort, authorities are targeting corrupt officials who have sent family members and assets overseas. The efforts have stirred up a debate at home on exactly how many officials take that route and how likely it is they will be caught. Rebecca Valli has this report.
Video

Video Leading The Fight Against Islamic State, Kurds Question Iraqi Future

Western countries including the United States have begun arming the Kurdish Peshmerga forces in northern Iraq to aid their battle against extremist Sunni militants from the Islamic State. But there are concerns that a heavily-armed Kurdistan Regional Government, or KRG, might seek to declare independence and cause the break-up of the Iraqi state. As Henry Ridgwell reports from London, the KRG says it will only seek greater autonomy from Baghdad.
Video

Video In Rural Kenya, Pressure Builds Against Female Circumcision

In some Kenyan communities, female genital mutilation remains a rite of passage. But activists are pushing back, with education for girls and with threats of punishment those who perform the circumcision. Mohammed Yusuf looks at the practice in the rural eastern community of Tharaka-Nithi.

AppleAndroid