The team needed more than mere presumptions and required proof. They contacted colleagues from New-Zealand in order to determine whether they too noticed the same phenomenon. The Southern Hemisphere remains well-preserved for the moment. This led the researchers to believe that the origin of the pollution was in the Northern Hemisphere and that ethane does not survive long enough in the atmosphere to drift below the Equator in significant quantities.

In orbit

The researchers then turned to the sky and the Canadian ACE instrument which has been in orbit since 2004. Their objective was to establish whether the measurements taken from the ground were similar to those detected in space. The results concurred. Above the American continent, the satellite even noticed increases of up to 10% per year!

In order to confirm its theory again, ULg turned to the NDACC (Network for the Detection of Atmospheric Composition Change), which combines several different sites that are similar to Jungfraujoch, particularly in the US, Canada and the Great North… “Our colleagues carried out the same analysis and confirmed the same trend that we had identified”, explains Emmanuel Mahieu.

There was hardly any room left for doubt. How was it possible that the American stations did not notice these massive releases of ethane under their very noses until the specialists from Liege armed with the data taken in Switzerland alerted them to the problem? “Our techniques enable us to analyse some twenty constituents, we cannot, however, analyse everything at the same time. It all depends on the priorities of each laboratory”, replies the head of GIRPAS. “There were actually some studies being done on methane but the problem is that there are many sources of this gas. It is therefore more difficult to identify the place where the problem originates. This is why we focus on ethane even if we are studying both gases”.

Who leaked?

The next stage of the research will be to quantify and identify the source of the emissions. What is the real extent of these leaks? Where precisely are they coming from? In order to establish this, the researchers will resort to what is called “reverse modeling”. The measurements taken by satellite will be used to deduce the location of the source and intensity of the emissions. This method is suitable for methane but because it is emitted simultaneously with ethane it should be possible to draw useful conclusions.

“The objective is to determine whether our model is capable of reproducing the trends detected. If we can’t not do this, it signifies that there are other elements in different places which have been under-estimated”, explains Emmanuel Mahieu. “Otherwise we will carry out sensitivity tests: by how much should we increase the emissions to achieve the atmospheric levels recorded”?

The last phase will consist of evaluating the real impact on the quality of the air. “We still have a lot to do”! Our conclusions could be released in 18 to 24 months’ time if the necessary funding is provided for the research. A scientific article focussing on improved analysis of spectroscopic parameters revealing the recent increase of ethane detected at Jungfraujoch has already been published (1) in March in JQSRT (Journal of Quantitative Spectroscopy and Radiative Transfer). Another article is being prepared focussing this time on the comparison of ethane leaks detected by the different measurement sites.

Priority to methane

The objective of the researchers is not to lead a crusade against shale gas. Quite the contrary. According to Emmanuel Mahieu, it is better to exploit methane for electricity than to use coal. “I will be considered mad because this is a greenhouse gas”, he smiles. “It is true that it is a greenhouse gas but if it comes to a choice between the two methane is the better option. Coal contains sulphur, emits more microparticles into the atmosphere and is less efficient with regard to conversion into electricity”. In any event, if the leaks are seen to be greater than 3%, the opposite is true. The first becomes less interesting than the second”.

This is why it is necessary to optimize the process of extraction and continue to closely monitor the situation. Finally, it remains to be seen whether the massive drilling in the US and the use of pumps, machines and trucks (machines which use diesel) cause an increase in the release of other constituents such as benzene and its derivatives which are known to be carcinogenic.

(1) Retrieval of ethane from ground-based FTIR solar spectra using improved spectroscopy: recent burden increase above Jungfraujoch, Franco et al. (2015), Journal of quantitative Spectroscopy and Radiative Transfer, 160, 36-49, doi:10.1016/j.jqsrt.2015.03.017.