The US and the EU announcement of a global partnership to cut emissions of the greenhouse gas methane by 2030 has been welcomed by a University of Sussex climate expert and former UN scientist.

EU Commission chief Ursula von der Leyen and US President Joe Biden made the announcement at the COP26 summit on Tuesday with the Global Methane Pledge aiming to limit methane emissions by 30% compared with 2020 levels.

More than 100 countries have signed up to the initiative for what is considered the most potent greenhouse gase after carbon dioxide and responsible for a third of current warming from human activities which Professor Joseph Alcamo has hailed as an "important development".

Professor Alcamo is an environmental systems scientist and from 2014 to 2016 held the UN post of Special Science Advisor to Christiana Figueres, the Head of the Paris Climate Agreement negotiations. He also served as the Chief Scientist of the UN’s Environment Programme and is now the Director of the Sussex Sustainability Research Programme at the University of Sussex.

In 2012, while serving as Chief Scientist of UNEP, Alcamo worked with the governments of Bangladesh, Canada, Ghana, Mexico, Sweden and the United States to help found the international Climate and Clean Air Coalition (CCAC). The CCAC has played a leading global role in convincing governments to draw down methane pollution for nearly a decade.

Prof Alcamo said: “This is an important development because methane is a nasty climate-actor, with each kilogramme of methane having the same global warming effect as 30 kilogrammes of carbon dioxide.

"Since methane lasts for a much shorter time in the atmosphere than carbon dioxide, any action to reduce methane emissions will lead to a fairly quick reaction time in the atmosphere. Drawing down its emissions will not stop or reverse climate change, but it will slow it down – It will buy us some time while we figure out how to cope with the climate change already kicking-in and how we are going to reach net zero.

“Drawing down methane also has important side benefits. One of the biggest is that methane is a major source of another nasty actor – ground-level ozone. So reducing the level of methane in the atmosphere has the beneficial knock-on effect of reducing ground-level ozone and its risk to health and crops.

“Drawing down methane emissions can be achieved using well known techniques and doesn’t require any major technological advances. But the big industrialised countries now have to step up and provide the needed technical know-how to the Global South.”