Zero-degree line at record height amid EU heatwaves and fires

Climate scientists typically use weather balloons to monitor the threshold for warming air. In Switzerland, the latest balloon climbed a record 5,300 metres before temperatures fell to zero degrees.

We just keep on breaking records for the wrong reasons.

Amid a backdrop of late summer heatwaves and raging wildfires across Europe, meteorologists set out to measure the zero degree line of our climate for 2023.

If you’re unfamiliar, this term refers to the altitude at which our atmospheric temperature falls below freezing and has become a key marker for climate models globally. The lower the heat threshold, the better our outlook on global warming.

The line ‘affects vegetation, the snow line, and the water cycle… so has a considerable impact on the habitats of humans, animals, and plants alike’, explains MeteoSwiss, the federal office for climatology.

Released and recorded overnight from atop the mountains of western Switzerland, the latest balloon reached a maximum height of 5,298 metres before temperatures reached zero.