DeBriefed 26 June 2026: Heat records broken across Europe | London climate action week | Introducing ‘Project Cosmos’

Welcome to Carbon Brief’s De Briefed. An essential guide to the week’s key developments relating to climate change. This week Record Europe heat HOTTEST EVER: The UK broke its temperature record for June twice this week, while France recorded its hottest day ever two days in a row, reported the Guardian. The Times reported that temperatures reached 36.7C in Somerset on Thursday, as the “London Ambulance Service had its busiest-ever day for life-threatening emergencies”. FRANCE FRYING: French newspaper Libération said that temperatures reached as high as 44.3C in the south-western commune of Pissos on Wednesday. Spain also recorded its highest daily average temperature for June, said BBC News. On Thursday, Switzerland also had its hottest June day, when temperatures reached 37C in four locations, reported SwissInfo. CLIMATE LINK: CNN covered a rapid analysis from the World Weather Attribution service finding that fossil-fuelled climate change has made this heatwave the most severe and widespread in Europe’s history. Carbon Brief covered the broken heat records, explaining the influence of climate change. ‘Electrifying’ London talks ‘LONDON COOKING’: In a sweltering, packed-out event at London climate action week, UN chief António Guterres quipped that “London is not just calling, it’s cooking”, reported Edie. Guterres also used his address to release a “global call to action on methane” and to call on artificial intelligence companies to reveal their environmental impact and source their power solely from renewables by 2030, said the publication. ‘ELECTRIFY NOW’: Elsewhere, dozens of governments, led by the EU and the UK, committed to throwing “their political weight” behind a rapid electrification of the world’s economy, according to Climate Home News. A high-level summit in London’s Mansion House saw energy ministers and business leaders, joined by Guterres, in “calling for faster action to curb demand for oil, coal and gas by powering homes, industry and tran