Independently control greenhouse gases
Errors occur when estimating emissions of climate-damaging gases such as carbon dioxide and methane. Researchers funded by the Swiss National Science Foundation have developed a method to independently verify countries' data.
With the Kyoto Protocol and the new Paris Climate Agreement, 195 countries have committed themselves to limiting global warming. The countries themselves check whether they are actually making the necessary reductions in greenhouse gases on the basis of estimates and projections. The uncertainties are great and errors can creep in. Researchers supported by the Swiss National Science Foundation (SNSF) have developed a method to independently check this information by directly measuring the gases in the atmosphere.
Hardly any leaks in the natural gas pipelines
For this purpose, researchers from Empa in Dübendorf, the University of Bern and ETH Zurich combined the measured data for methane (CH4) with a dispersion model for air pollutants in Switzerland. The result: The values determined for 2013 deviated only slightly from the figures of the Federal Office for the Environment (FOEN) and thus confirmed the estimated annual emission of around 200,000 tons of methane.
The share of livestock, which accounts for the lion's share of methane emissions (70 percent), turned out to be somewhat lower than previously estimated. On the other hand, it was confirmed that natural gas pipelines in Swiss cities hardly leak at all. Previously, the assumptions on this were very uncertain. The higher-than-assumed methane emissions in northeastern Switzerland were surprising. "We are now planning a measurement campaign closer to the affected areas to verify whether the difference is indeed real," says Dominik Brunner, atmospheric physicist and head of the study at Empa.
For the model, Brunner and his colleagues integrated data from two measuring stations newly set up for this purpose on the Lägeren near Baden and on the former radio transmission tower in Beromünster (LU), as well as from two other sites in the Swiss midlands. A few sites are sufficient for determining methane emissions in Switzerland. Thanks to the weather model of the Federal Office of Meteorology and Climatology (Meteoschweiz), the tortuous paths of the air parcels can be traced back across the Atlantic over several days.
Supplementation of the European measurement network
"We have refined the resolution of the inverse modeling, which has already been applied to larger-scale areas such as the USA, and adapted it to the scale of Switzerland with its difficult topography," says Stephan Henne, the study's lead author. The FOEN is expected to publish the study as an annex to Switzerland's latest greenhouse gas inventory on April 15, 2016. This places Switzerland, along with the United Kingdom and Australia, among the first three countries to publish an independent review of its figures.
The project called CarboCount-CH is considered a pilot project for a pan-European measuring network "Integrated Carbon Observation System" (ICOS), which will record the greenhouse gas emissions of all countries in Europe in the future. "With our CarboCount-CH measuring network, we will next investigate the uptake of carbon dioxide (CO2) by vegetation," says Henne.
