Alumni Zoom Series: 'Methane Emissions: Wetlands, Gas leaks, Coal, Fires and Cows (and a few hippos, buffalo, and camels)'

Speaker:
Professor Euan Nisbet. Alumnus and Honorary Fellow of Darwin.

Booking:
Invitations will be sent out to alumni in appropriate time-zones three weeks before the zoom talk. If you would like an invitation please email alumni@darwin.cam.ac.uk

Talk Synopsis:
Methane is the second-most important anthropogenic greenhouse gas after carbon dioxide. The major sources are wetlands, fossil fuel emissions from the gas, coal and oil industries, the breath of cattle and other ruminants, landfills and waste, and biomass fires. The largest sink is atmospheric OH, especially in the tropical mid-troposphere, as well as soils and atmospheric Cl. Methane grew from about 720 ppb in pre-industrial air to nearly 1900 ppb now. With a direct heating impact of about 0.5 W per sq m and around 1 W per sq m if indirect effects are included, the climate warming impacts of anthropogenic methane emissions are very important. This rise, predominantly caused by human activity, is proportionately much greater than the increase in carbon dioxide­.

“MOYA”, the UK’s Natural Environment Research Council’s project on the Global Methane Budget (2016-2021) was a wide-ranging study of all aspects of atmospheric methane. Our work included in situ measurement at remote locations such as Ascension Island and Chacaltaya in Bolivia (>5km altitude) and a wide range of field campaigns on the ground and in aircraft. Linked to MOYA was the ZWAMPS aircraft campaign, studying the Upper Congo and Zambezi wetlands of Zambia.

Methane growth is arguably the strongest threat so far to the success of the Paris Agreement. The year 2020 had the fastest methane growth in the observational record. Is the warming feeding the warming? We do not know whether recent growth is largely directly caused by humans, or by feedbacks such as more methane from warmer wetter wetlands. In order to reverse the current increase, the task of mitigating anthropogenic sources is urgent, and perhaps even in special cases removing methane from the atmosphere,