The last 12 months were the hottest on record, temporarily sending the world past a deeply symbolic mark.
For the first time, global warming has exceeded 1.5C across an entire year, according to the EU's climate service.
A landmark UN report in 2018 said that the risks from climate change - such as intense heatwaves, rising sea-levels and loss of wildlife - were much higher at 2C of warming than at 1.5C. But all the major datasets agree on the recent warming trajectory and that the world is in by far its warmest period since modern records began - and likely for much longer.And the world's sea surface is also at its highest ever recorded average temperature - yet another sign of the widespread nature of climate records. As the chart below shows, it's particularly notable given that ocean temperatures don't normally peak for another month or so.
But human activities mean temperatures will ultimately continue rising in the decades ahead, unless urgent action is taken. This would be a hugely symbolic milestone, but researchers say it wouldn't mark a climate cliff edge.