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Taking the atmosphere’s pulse

The carbon dioxide concentration (CO2) in the atmosphere has risen to nearly a 1.5-fold higher concentration in 2016, and it continues to rise.

Compared to the preindustrial era, the carbon dioxide concentration (CO2) in the atmosphere has risen to nearly a 1.5-fold higher concentration in 2016, and it continues to rise. As part of the Global Atmosphere Watch programme of the World Meteorological Organization (WMO), more than 50 nations are jointly monitoring greenhouse gases such as CO2, methane and nitrous oxide. Within this context, well over 150 experts from around the globe are convening at Empa from 28 to 31 August to discuss the fundamental principles for long-term measurements and to develop new measurement techniques.

The researchers who are participating in the GAW programme of the WMO specialize in taking the atmosphere’s pulse. For example, they monitor the atmospheric CO2 concentration by means of online measurements and analyze its sources and sinks. According to WMO’s Greenhouse Gas Bulletin, roughly two thirds of the global greenhouse effect are due to CO2. The second most important greenhouse gas, methane (CH4), contributes approximately 17 percent. Nitrous oxide (N2O) follows in third place with a contribution of about 6 percent.

Why do we need global coordination of measurements?
The quantification of the relevant processes, i.e., answering the question who contributes how much to the greenhouse effect and in which manner, is a prerequisite for developing and implementing appropriate reduction measures and requires the worldwide coordination of the observations. Measurement data must be of high quality and comparable around the globe to be able to detect even small regional differences and trends and to be able to draw reliable conclusions.

Since the mid-1990s, Empa has been operating two “Central Facilities” that audit and support global measurement stations in order to achieve the required quality targets. As part of these responsibilities, Empa has invited international experts to the biannual GGMT-2017 conference (officially: 19th WMO/IAEA Meeting on Carbon Dioxide, Other Greenhouse Gases and Related Measurement Techniques) in Dübendorf, Switzerland. GGMT-2017 takes place immediately after the 10th International Carbon Dioxide Conference (ICDC 10), which brought together international climate researchers from 21 to 25 August in Interlaken, Switzerland.

Online monitoring in Hawaii, in Beromünster and at Jungfraujoch
The measurement of greenhouse gases is extremely demanding because they are only present in the atmosphere in trace amounts. For example, the CO2 concentration in air is currently 400 ppm (parts per million) – which is 0.04 percent. Since 2000, Empa and the University of Bern have monitored the CO2 concentration in the air above Europe at their measurement station at Jungfraujoch, which is part of the global GAW network. The measurements in Switzerland show a continuous increase in the CO2 concentration comparable to that recorded at the Mauna Loa Observatory in Hawaii, where the CO2 concentration has been measured since 1958.

Measurements at Jungfraujoch, in combination with the investigation of the atmospheric transport, provide insights into the origin of the greenhouse gas: since 2008, a prototype developed at Empa is the first instrument worldwide that also continuously measures the concentration of the natural carbon isotope 13C as well as of the oxygen isotope 18O in CO2. This allows detailed inferences about CO2 sources and sinks. For instance, from spring to fall CO2 concentrations decrease significantly during the afternoon. This decrease can be attributed to the photosynthetic activity of plants, which peaks during the afternoon; this is also reflected in a characteristic enrichment in 13C in CO2. (12C as compared to 13C is preferentially converted into sugar by plants during photosynthesis.)

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Source   Empa | 2017

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