2023 looks set to be a watershed year for the climate

In June Vivek Ramaswamy, a Republican presidential hopeful, posted two covers of Time magazine on social media. The first, from 1973, had the headline “The Big Freeze”; the second, from 1979, proclaimed “The Cooling of America”. Both, he argued, showed how the world once fretted about “global cooling” instead of global warming. This was evidence, he said, of “climate cult mania” today.

Neither cover was in fact about the environment (both related to energy shortages). But even the most belligerent sceptics should struggle to argue away the implications of the latest batch of climate data. Copernicus, the Earth-observation programme run by the European Union; Berkeley Earth, an American research group; and NASA’s Goddard Institute for Space Studies each month release analyses of global temperatures for the previous month. None has ever been as dramatic as those for September. Not only was it the hottest September on record, it was also the month with the most excess heat ever. NASA’s data, published on October 13th, showed an average monthly surface temperature (across both land and ocean) of 1.47°C above the normal for Septembers in its base period of 1951 to 1980. Copernicus put September’s average absolute air temperature at 16.38°C, an astonishing 0.5°C warmer than the previous record.

September’s spike, though extraordinarily large, is also not the first time in recent months that climate analysts have been forced to expand their y-axes. June, July and August were scorching months: combined average temperatures were 1.2C above the 1951-1980 average, according to NASA. Even greater warming in September means it is almost certain that 2023 will be unprecedentedly hot—Berkeley Earth says it is more than 99% likely that it will be the warmest year since its records began in 1850.

The group also reckons that it is more than 90% likely that 2023’s average temperature will be the first to exceed 1.5°C above pre-industrial levels. That would be a watershed moment. The Paris Agreement, negotiated in 2015 and to which 194 states and the EU are now beholden, committed signatories to keeping the global temperature rise below 1.5°C (or, failing that, to “well below” 2°C). These limits, it was decided, were needed to avoid the worst consequences of climate change. The latest data do not mean the targets have been missed already. The Paris goals apply to long-term temperature trends to 2100, rather than any single year. But it is now generally acknowledged by scientists that sticking to the 1.5°C target is practically impossible. Breaching that talismanic threshold so soon should only be interpreted as a terrifying sign, even by the likes of Mr Ramaswamy.■