The climate system on which we depend for everything is breaking down before our eyes. The scale and speed of what is happening is truly terrifying and requires an emergency response that jolts us out of our inaction.

Some scientists knew about the relevant atmospheric physics as far back as the 1850s. The oil industry also commissioned its own research in the 1970s, which made clear the risks – a Harvard analysis found internal projections made by ExxonMobil from 1977-2003 were “shockingly” accurate – but the industry decided to keep the information to itself. It was only in 1988 that the alarm was properly raised when the Intergovernmental Panel on Climate Change (IPCC) was established and James Hansen, director of the Nasa Goddard Institute for Space Studies, set out the principles of climate science in a US Senate hearing.

Those key principles soon became incontrovertible and verified by every credible test. However, the timing was still somewhat uncertain. The assumptions involved in climate modelling made it hard to judge exactly how our complex planetary systems would work in this fast-changing world. Unfortunately, it now seems that the models underestimated rather than exaggerated the problem.

Real-time measurements mean we are no longer just modelling what might happen. The latest data shows we are experiencing an........

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