Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ancient global warming episode holds clues to future climate

21.07.2009
When scientists take Earth's temperature, they usually use thermometers. But when scientists want to figure out Earth's temperature in the past, they have to rely on other tools.

One of these is deep-sea sediment cores (see Figure). Deep-sea sediments contain fossil remains of tiny marine creatures and other materials that sink to the ocean floor. Over millions of years, these materials pile up and build climate archives that tell stories about Earth's history. Today, scientists recover those archives during ocean drilling expeditions aboard research vessels such as the JOIDES Resolution (see Figure).

Now a team of scientists, led by Richard Zeebe of the University of Hawai'i at Manoa's School of Ocean and Earth Science and Technology, has examined data from sediment cores from around the world to study an ancient global warming episode, known as the Paleocene-Eocene Thermal Maximum. This warming event occurred about 55 million years ago and provides important clues about what the future may hold. By studying the past, the researchers contribute to better forecasting the future – a principle once expressed by the English historian Edward Gibbon: "I know no way of judging of the future but by the past."

There is little doubt among scientists that the Earth is warming because of carbon dioxide emissions from human activities. But exactly how much the Earth will warm – say until the end of the 21st century – is still uncertain. In their study published in the journal Nature Geoscience, Zeebe and his team help to resolve the question by studying a possible analog in the past. Using sediment archives and theoretical tools, they provide estimates of the amount of carbon dioxide in the atmosphere during the warming episode 55 million years ago.

The team had to go back that far in time because this event may be the only one during the past 55 million years of similar scale and pace as the current human disruption. At that time, global surface temperatures rose by 5°C within a few thousand years. At nearly the same time, a large amount of carbon was released, probably from the dissociation of oceanic methane hydrates. By comparing the change in ancient temperature and carbon dioxide levels, Zeebe and his team provide clues about the magnitude of global warming during large and rapid increases of greenhouse gases.

What the team found was quite unexpected. Based on current knowledge about Earth's climate system, they expected a three- to eightfold increase in atmospheric carbon dioxide levels to explain the 5°C warming. Yet, they found only a less-than-twofold increase.

Zeebe, an oceanographer at UH Manoa, says: "We were pretty surprised that the increase in atmospheric carbon dioxide turned out to be so small. To explain the entire warming, you would need a whole lot more carbon."

The consequence is that other mechanisms must have considerably contributed to the warming 55 million years ago. Unfortunately, these mechanisms are unknown at present.

"There are a few ideas what may have contributed to the additional warming. But I don't think we fully understand these events of intense and rapid global warming," says Zeebe.

If the additional warming in the past was a response to rising carbon dioxide, then also future warming could be much stronger than anticipated. Undoubtedly, the Earth was a different place 55 million years ago and comparison with today's situation is imperfect. Nevertheless, the work of Zeebe and his co-workers suggests that the future climate could hold some surprises.

"By continuing to put these huge amounts of carbon dioxide in the atmosphere, we're gambling with climate and the outcome is still uncertain," Zeebe says.

Zeebe, R. E., Zachos, J. C., and Dickens, G. R. Carbon dioxide forcing alone insufficient to explain Paleocene-Eocene Thermal Maximum warming. Nature Geoscience, Advance Online Publication, July 13, 2009.

The University of Hawai`i at Manoa serves approximately 20,000 students pursuing 225 different degrees. Coming from every Hawaiian island, every state in the nation, and more than 100 countries, UH Manoa students matriculate in an enriching environment for the global exchange of ideas.

Richard E. Zeebe | EurekAlert!
Further information:
http://www.hawaii.edu
http://manoa.hawaii.edu

More articles from Earth Sciences:

nachricht A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington

nachricht Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>