SHOW CASE A "METHANE"
Man-made and natural CH4 and VOC emissions from marine and terrestrial sources in the North Sea region
Although the atmospheric abundance of methane (CH4) is about 200 times smaller compared to that of carbon dioxide (CO2), it is a far more potent warming agent as its greenhouse warming potential (GWP) is 25-30 times larger (depending on the considered time frame) than that of CO2 (IPCC 2013).
Today anthropogenic sources of agriculture/waste and biomass burning are the dominating methane fluxes into the atmosphere, followed by natural sources e.g. from wetlands in tropical and Arctic regions or other geological sources (e.g. Kirschke et al. 2013). However, also leakage of methane and volatile organic compounds (VOCs) from oil, gas and coal exploration on land and at sea leads to in detail yet not quantified emissions, which manifests in huge discrepancies in top-down and bottom-up estimates of the methane emissions (IPCC 2013). To overcome this discrepancy and to distinguish natural from anthropogenic sources, an evaluation of individual, local sources (e.g. leaking oil and gas wells) by detailed field studies accompanied by high resolution modelling is needed to assess the impact of local CH4 and VOC sources on atmospheric concentrations.
As an example for strong local gas emissions, Show Case A we focus on the North Sea region as it shows specific anthropogenic (active and abandoned gas wells; Vielstädte et al. 2016) and natural sources and sinks. During Digital Earth existing marine data as well as those from data bases (e.g. MEMENTO) are collected and complemented by additionally acquired data during marine cruise and air plane campaigns (GEOMAR, UFZ, DLR, GFZ, MOSES & CoMET campaigns).