Featured Research

from universities, journals, and other organizations

Earth's breathable atmosphere a result of continents taking control of the carbon cycle

Date:
June 9, 2014
Source:
University of Exeter
Summary:
Scientists investigating one of the greatest riddles of the Earth's past may have discovered a mechanism to help determine how oxygen levels in the atmosphere expanded to allow life to evolve.

How did oxygen levels in the atmosphere expand enough to allow life to evolve? Researchers may have solved one of the biggest puzzles in geochemistry.
Credit: Copyright Michele Hogan

Scientists investigating one of the greatest riddles of Earth's past may have discovered a mechanism to help determine how oxygen levels in the atmosphere expanded to allow life to evolve.

High concentrations of atmospheric oxygen have been essential for the evolution of complex life on Earth. Over the 4.5 billion years of Earth history, oxygen concentration has risen from trace amounts to 21% of the atmosphere today. However, the mechanisms behind this rise are uncertain, and it remains one of the biggest puzzles in geochemistry.

A research group from the University of Exeter has discovered one possible mechanism, relating to the way in which carbon dioxide is removed from the atmosphere over long timescales.

Dr Benjamin Mills, of Geography, said: "On the early Earth, CO2 levels were controlled by hydrothermal processes on the seafloor. As Earth cooled, and the continents grew, chemical processes on the continents took over."

Using computer models, the group has shown that this switch may explain increasing oxygen concentration over Earth's middle age (the Proterozoic era), which ultimately led to conditions suitable for complex life. According to the authors, the oxygen rise is caused by a gradual increase in marine limiting nutrients, which are a product of chemical weathering of the continents.

Dr Mills added: "The more CO2 that is sequestered by continental weathering, the larger the phosphate source to the oceans. Phosphate availability controls the long term photosynthetic productivity, which leads to oxygen production."

"This is not the only reason oxygen rose to high levels, but it seems to be an important piece of the puzzle. Whilst the carbon cycle can function without large continents, it seems that their emergence was critical to our own evolution."


Story Source:

The above story is based on materials provided by University of Exeter. Note: Materials may be edited for content and length.


Journal Reference:

  1. Benjamin Mills, Timothy M. Lenton, and Andrew J. Watson. Proterozoic oxygen rise linked to shifting balance between seafloor and terrestrial weathering. PNAS, June 9, 2014 DOI: 10.1073/pnas.1321679111

Cite This Page:

University of Exeter. "Earth's breathable atmosphere a result of continents taking control of the carbon cycle." ScienceDaily. ScienceDaily, 9 June 2014. <www.sciencedaily.com/releases/2014/06/140609153433.htm>.
University of Exeter. (2014, June 9). Earth's breathable atmosphere a result of continents taking control of the carbon cycle. ScienceDaily. Retrieved August 31, 2014 from www.sciencedaily.com/releases/2014/06/140609153433.htm
University of Exeter. "Earth's breathable atmosphere a result of continents taking control of the carbon cycle." ScienceDaily. www.sciencedaily.com/releases/2014/06/140609153433.htm (accessed August 31, 2014).

Share This




More Earth & Climate News

Sunday, August 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Volcano Erupts on Papua New Guinea

Raw: Volcano Erupts on Papua New Guinea

AP (Aug. 29, 2014) Several communities were evacuated and some international flights were diverted on Friday after one of the most active volcanos in the region erupts. (Aug. 29) Video provided by AP
Powered by NewsLook.com
Raw: Small Volcanic Eruption in Iceland

Raw: Small Volcanic Eruption in Iceland

AP (Aug. 29, 2014) Icelandic authorities briefly raised the aviation warning code to red on Friday during a small eruption at the Holuhraun lava field in the Bardabunga volcano system. (Aug. 29) Video provided by AP
Powered by NewsLook.com
As Drought Continues LA "water Police" Fight Waste

As Drought Continues LA "water Police" Fight Waste

AFP (Aug. 29, 2014) In the midst of a historic drought, Los Angeles is increasing efforts to go after people who waste water. Five water conservation "cops" drive around the city every day educating homeowners about the drought. Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins