Featured Research

from universities, journals, and other organizations

Methane emissions can be traced back to Roman times

Date:
October 3, 2012
Source:
University of Copenhagen
Summary:
Emissions of the greenhouse gas methane into the atmosphere can be traced back thousands of years in the Greenland ice sheet. Using special analytical methods, researchers have determined how much methane originates from natural sources and how much is due to human activity. The results go back to Roman times and up to the present, where more than half of the emissions are now human-made.

The isotope curve shows that the emissions of the greenhouse gas methane had several peaks in the last 2,100 years. 1: During Roman times, where a lot of wood was burned for heating and for the processing of metals. 2: During the warm Middle Ages, where forests caught on fire. 3: In the "Little Ice Age", which was a very cold and dry period. 4: The methane concentration has increased dramatically since approx. the year 1800, when industrialization took off and triggered energy and food production, for example, rice fields.
Credit: NBI

Emissions of the greenhouse gas methane into the atmosphere can be traced back thousands of years in the Greenland ice sheet. Using special analytical methods, researchers from the Niels Bohr Institute, among others, have determined how much methane originates from natural sources and how much is due to human activity. The results go all the way back to Roman times and up to the present, where more than half of the emissions are now human-made.

The results are published in the scientific journal, Nature.

Methane is an important greenhouse gas, which today is partly emitted from natural sources and partly from human activities. The emissions from natural sources varies due to the climate variations. For example, bacteria in wetlands release methane and less is emitted in dry periods as the wetlands shrink.

Emissions of methane into the atmosphere also come from human actions. For example, methane is emitted from rice fields, which are of course wetlands, and methane is emitted from biomass burning, either from burning of forest areas for cultivation or the use of wood in furnaces. Energy production through coal combustion also produces methane gases. But how can you determine where the methane gas comes from?

Different sources can be traced

"The different sources of methane have different isotopic compositions. The methane produced by the burning of biomass, like wood, contains more of the heavier isotope (carbon-13) relative to the lighter isotope (carbon-12), than methane which is produced in wetlands," explains Professor Thomas Blunier, Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen. The researchers have measured the isotopic composition of the methane in ice cores that are drilled up from the Greenland ice cap at the NEEM project in northwestern Greenland. The ice cap is formed from snow that falls year after year and remains, gradually getting compressed into ice. The ice contains tiny air bubbles from the atmosphere in the snow that fell, and by analysing the composition of the air you can get a climate curve, which tells you about both the annual temperature and methane content.

The question is how far back in history man has had an impact on the methane concentration in the atmosphere?

Methane emissions are peaking now

"We have analysed the methane composition more than 2,000 years back in time. We can see that already 2,100 years ago during Roman times, some cultures were spreading out and burning large amounts of wood for fuel in furnaces to work with metals that required intense heat to process. But the level was still low. The next significant increase was during the Middle Ages around 1,000 years ago. It was a warm period and it was dry so there were presumably many forest fires that emitted methane while the wetlands dwindled and reduced methane emissions from that source. We also find emissions from natural forest fires and deforestation during the so-called 'Little Ice Age' (between 1350 and 1850), which was a very cold and dry period, Emissions of methane increased dramatically from around 1800, when the industrial revolution took off and where there occurred a large increase in population," explains Thomas Blunier.

The analyses show that from around the year 1800 there are large increases that are human-made. Approximately half originates from the production of food -- especially rice fields and cattle. Then a lot is emitted from the decomposition of organic materials that are deposited and methane is emitted from burning coal for energy.

"The extent to which our ancestors were able to influence the emissions of methane with their activities is surprising. The general trend from 100 BCE to the year 1600 shows a correlation between the increase in the appropriation of land for cultivation and the emission of the biogenic methane. Today, half of the methane emissions stem from human activities," says Thomas Blunier.


Story Source:

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


Journal Reference:

  1. C. J. Sapart, G. Monteil, M. Prokopiou, R. S. W. van de Wal, J. O. Kaplan, P. Sperlich, K. M. Krumhardt, C. van der Veen, S. Houweling, M. C. Krol, T. Blunier, T. Sowers, P. Martinerie, E. Witrant, D. Dahl-Jensen, T. Rφckmann. Natural and anthropogenic variations in methane sources during the past two millennia. Nature, 2012; 490 (7418): 85 DOI: 10.1038/nature11461

Cite This Page:

University of Copenhagen. "Methane emissions can be traced back to Roman times." ScienceDaily. ScienceDaily, 3 October 2012. <www.sciencedaily.com/releases/2012/10/121003132322.htm>.
University of Copenhagen. (2012, October 3). Methane emissions can be traced back to Roman times. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2012/10/121003132322.htm
University of Copenhagen. "Methane emissions can be traced back to Roman times." ScienceDaily. www.sciencedaily.com/releases/2012/10/121003132322.htm (accessed July 25, 2014).

Share This




More Earth & Climate News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) — The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) — Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Higgins Breaks Record at Mt. Washington

Higgins Breaks Record at Mt. Washington

Driving Sports (July 24, 2014) — Subaru Rally Team USA drivers David Higgins and Travis Pastrana face off against a global contingent of racers at the annual Mt. Washington Hillclimb in New Hampshire. Includes exclusive in-car footage from Higgins' record attempt. Video provided by Driving Sports
Powered by NewsLook.com
Storm Kills Three, Injures 20 at Virginia Campground

Storm Kills Three, Injures 20 at Virginia Campground

Reuters - US Online Video (July 24, 2014) — A likely tornado tears through an eastern Virginia campground, killing three and injuring at least 20. Linda So reports. Video provided by Reuters
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