Will the Earth breach its 1.5C guardrail sooner than we thought?

‘James Hansen and co have joined other scientists in noting events in Antarctica this year, particularly a sharp fall in the amount of sea ice surrounding the continent, may indicate it is joining the Arctic in becoming an important contributor to global heating.’ Photograph: Anadolu Agency/Getty Images

People tend to notice when James Hansen speaks, and with good reason. Sometimes described as the godfather of climate science, Hansen came to global attention in June 1988 when he was director of the Nasa Goddard Institute for Space Studies.

Invited to speak before a US Senate committee, he warned Nasa was 99% confident that human-made greenhouse gas emissions were already causing global warming, and the likelihood of extreme weather was increasing. Scientists and historians generally agree this forceful testimony 35 years ago was a turning point in mass awareness of a looming climate problem.