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

Video VOA EXCLUSIVE: Iraq President Vows to Fight IS 'Until They Are Killed or We Die'

In wide-ranging interview with VOA Persian service reporter, Fuad Masum describes conflict as new type of fight that will take time to win More

Video Russian Anti-Corruption Campaigner Slams Putin’s Crackdown on Dissent

In interview with VOA Alexei Navalny says he believes new law against 'undesirable NGOs' part of move to keep Russian president in power More

Video On The Scene: In Ethiopia, 'Are You a Journalist?' Is a Loaded Question

VOA's Anita Powell describes the difficulties faced by reporters in fully conveying the story in a country where people are reticent to share their true opinions 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.
Expelled from Pakistan, Afghan Refugees Return to Increased Hardshipi
X
Ayesha Tanzeem
May 28, 2015 6:48 PM
Undocumented refugees returning to Afghanistan from Pakistan have no jobs, no support system, and no home return to, and international aid agencies say they and the government are overwhelmed and under-resourced. Ayesha Tanzeem has more from Kabul.
Video

Video Expelled from Pakistan, Afghan Refugees Return to Increased Hardship

Undocumented refugees returning to Afghanistan from Pakistan have no jobs, no support system, and no home return to, and international aid agencies say they and the government are overwhelmed and under-resourced. Ayesha Tanzeem has more from Kabul.
Video

Video Britain Makes Controversial Move to Crack Down on Extremism

Britain is moving to tighten controls on extremist rhetoric, even when it does not incite violence or hatred -- a move that some are concerned might unduly restrict basic freedoms. It is an issue many countries are grappling with as extremist groups gain power in the Middle East, fueled in part by donations and fighters from the West. VOA’s Al Pessin reports from London.
Video

Video Floodwaters Recede in Houston, but Rain Continues

Many parts of Texas are recovering from one of the worst natural disasters to hit the southwestern state. Heavy rains on Monday and early Tuesday caused rivers to swell in eastern and central Texas, washing away homes and killing at least 13 people. As VOA’s Greg Flakus reports from Houston, floodwaters are receding slowly in the country's fourth-largest city, and there likely is to be more rain in the coming days.
Video

Video 3D Printer Makes Replica of Iconic Sports Car

Cars with parts made by 3D printers are already on the road, but engineers are still learning about this new technology. While testing the possibility of printing an entire car, researchers at the U.S. Department of Energy recently created an electric-powered replica of an iconic sports roadster. VOA’s George Putic has more.
Video

Video Al-Shabab Recruitment Drive Still on In Kenya

The al-Shabab militants that have long battled for control of Somalia also have recruited thousands of young people in Kenya, leaving many families disconsolate. Mohammed Yusuf recently visited the Kenyan town of Isiolo, and met with relatives of those recruited, as well as a many who have helped with the recruiting.
Video

Video US Voters Seek Answers From Presidential Candidates on IS Gains

The growth of the Islamic State militant group in Iraq and Syria comes as the 2016 U.S. presidential campaign kicks off in the Midwest state of Iowa.   As VOA’s Kane Farabaugh reports, voters want to know how the candidates would handle recent militant gains in the Middle East.
Video

Video A Small Oasis on Kabul's Outskirts Provides Relief From Security Tensions

When people in Kabul want to get away from the city and relax, many choose Qargha Lake, a small resort on the outskirts of Kabul. Ayesha Tanzeem visited and talked with people about the precious oasis.
Video

Video Film Festival Looks at Indigenous Peoples, Culture Conflict

A recent Los Angeles film festival highlighted the plight of people caught between two cultures. Mike O'Sullivan has more on the the Garifuna International Film Festival, a Los Angeles forum created by a woman from Central America who wants the world to know more about her culture.
Video

Video Kenyans Lament Losing Sons to al-Shabab

There is agony, fear and lost hope in the Kenyan town of Isiolo, a key target of a new al-Shabab recruitment drive. VOA's Mohammed Yusuf visits Isiolo to speak with families and at least one man who says he was a recruiter.
Video

Video Scientists Say Plankton More Important Than Previously Thought

Tiny ocean creatures called plankton are mostly thought of as food for whales and other large marine animals, but a four-year global study discovered, among other things, that plankton are a major source of oxygen on our planet. VOA’s George Putic reports.
Video

Video Kenya’s Capital Sees Rise in Shisha Parlors

In Kenya, the smoking of shisha, a type of flavored tobacco, is the latest craze. Patrons are flocking to shisha parlors to smoke and socialize. But the practice can be addictive and harmful, though many dabblers may not realize the dangers, according to a new review. Lenny Ruvaga has more on the story for VOA from Nairobi, Kenya.
Video

Video Iowa Family's Sacrifice Shaped US Military Service for Generations

Few places in America have experienced war like Waterloo. This small town in the Midwest state of Iowa became famous during World War II not for what it accomplished, but what it lost. As VOA’s Kane Farabaugh reports, the legacy of one family’s sacrifice is still a reminder today of the real cost of war for all families on the homefront.

VOA Blogs