ScienceDaily (Nov. 23, 2009) — Of all global carbon dioxide emissions, less than half accumulate in the atmosphere where it contributes to global warming. The remainder is hidden away in oceans and terrestrial ecosystems such as forests, grasslands and peat-lands. Stimulating this "free service" of aquatic and terrestrial ecosystems is considered one of the main, immediately available ways of reducing climate change. However, new greenhouse gas bookkeeping has revealed that for the European continent this service isn't free after all.

These findings were recently published in Nature Geoscience.

Researchers from 17 European countries cooperating in the EU-Integrated Project CarboEurope, led by Detlef Schulze, of the Max Planck Institute for Biogeochemistry in Jena, Germany have compiled the first comprehensive greenhouse gas balance of Europe. They made two independent estimates: one based on what the atmosphere sees and one based on what terrestrial ecosystems see.

The new bookkeeping effort confirmed the existence of a strong carbon sink of -305 Million tonnes of carbon per year in European forests and grasslands. A sink of this magnitude could offset 19% of the emission from fossil fuel burning. However, agricultural land and drained peat-land are emitting CO₂, which cancels part of this sink. The resulting net CO₂ sink of the European continent is 274 Million tonnes of carbon per year -- only 15% of the emissions from fossil fuel burning. But this balance is still incomplete, because all European ecosystems are managed and as a by-product of land management other powerful greenhouse gases are released -- for example nitrous oxide from fertilizers applied to grassland and crops, and methane from ruminants and from peat-lands. These previously neglected emissions of greenhouse gases from land-use cancel out almost the entire carbon sink, leaving the landscape offsetting only some 2% of the CO₂ emissions from households, transport and industry.

Compared to Europe as a whole, the situation is even worse for the 25 states of the European Union. Here, although forests and grasslands can compensate for 13% of the CO₂ emitted by fossil fuel burning, emission of powerful greenhouse gases from agricultural emissions and peat mining reduces the effectiveness of the land surface sink to 111 Million tonnes of carbon per year, which is only 11% of the CO₂ emitted by fossil fuels. However, since the emissions of methane and nitrous oxide are relatively higher in the European Union the land surface emerges as a greenhouse gas source of 34 Million tonnes of carbon per year. This effectively increases the emissions from fossil fuel burning by another 3%.

Prof Schulze said "These findings show that if the European landscape is to contribute to mitigating global warming, we need a new, different emphasis on land management. Methane and nitrous oxide are such powerful greenhouse gases; we must manage the landscape to decrease their emissions."

Recommend this story on Facebook, Twitter,
and Google +1:

Other bookmarking and sharing tools:

Story Source:

The above story is reprinted from materials provided by Max-Planck-Gesellschaft.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

1. Schulze et al. Importance of methane and nitrous oxide for Europe's terrestrial greenhouse-gas balance. Nature Geoscience, 2009; DOI: 10.1038/ngeo686

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

enlarge

Fig.: In order to compute whether European landscapes store or release greenhouse gases, climatologists have for the first time also considered methane and nitrogen oxide emissions from livestock farming and intensive agriculture. The bottom line is that forests, grasslands and agriculture fields, particularly in central Europe, freely release greenhouse gas (in carbon dioxide equivalents / red colouring in diagram). In this way they balance out the effect which Russian forests have as a source of carbon dioxide storage (blue colouring), almost completely. (Credit: CarboEurope Team)

Related Stories

How Grazing Lands Influence Greenhouse Gas (May 24, 2010) — Scientists estimated net global warming potential for three grazing management systems located in central North Dakota. The results indicate that grazing lands are strong sinks of soil organic carbon ...  > read more

Biodiesel Won't Drive Down Global Warming (Apr. 23, 2007) — European Union legislation to promote the uptake of biodiesel could increase rather than decrease greenhouse gas emissions. A recent study revealed that while petroleum diesel emits 85 percent of its ...  > read more

Nitrous Oxide: Definitely No Laughing Matter When It Comes To Global Warming (Feb. 18, 2008) — Farmers, food suppliers, policy-makers, business leaders and environmentalists are joining forces to confront the threat of the "forgotten greenhouse gas." Better known as 'laughing gas', nitrous ...  > read more

Greenhouse Gases from Forest Soils (Apr. 12, 2011) — Reactive nitrogen compounds from agriculture, transport, and industry lead to increased emissions of the greenhouse gas nitrous oxide from forests in Europe. Nitrous oxide emission from forest soils ...  > read more

Urban 'Green' Spaces May Contribute to Global Warming (Jan. 22, 2010) — Dispelling the notion that urban "green" spaces help counteract greenhouse gas emissions, new research has found -- in Southern California at least -- that total emissions might be lower if lawns did ...  > read more

Search ScienceDaily