20 May, 2025

Isabelle Gerretsen This week, we meet the pilots who are chasing the weather phenomena known as atmospheric rivers through the sky, from Japan to California. These "sky rivers" are the main cause of flood damage in the western US and, as Sophie Hardach reports, they are becoming bigger and more frequent due to climate change. Plus: what chestnuts reveal about the Roman Empire.

CLIMATE CONVERSATION Chasing 'sky rivers' from Japan to the US Storm-hunting planes are capturing real-time data on atmospheric rivers. Credit: US Air Force US Air Force pilots started operating flights out of Japan this year, chasing atmospheric rivers through the sky all the way to the US. They hope that by gathering real-time data, they can help protect communities from these powerful storms.  ‌ Atmospheric rivers are invisible ribbons of water vapour. When they reach the coast and flow up to the mountains, the vapour cools and turns into rain or snow. This often leads to devastating floods – atmospheric rivers cause more than $1bn (£753m) in flood damage in the western US each year. But these "sky rivers" are also important for preventing droughts – they hit just a few days each year, but they contribute up to 50% of California's annual rainfall. ‌ The data captured by the storm-hunting flights results in more accurate forecasting, which helps weather services issue timely warnings and allows reservoir managers to decide whether to capture the coming rain and prevent flooding. To discover more about "sky rivers" – and how we can keep ourselves safe – click the button below. Read more

THE BIG PICTURE 'You're supposed to hate snakes - I don't' Rescuers are helping save rattlesnakes in Arizona. Credit: Getty Images Every year, 7,000-8,000 people are bitten by venomous snakes in the US and around five die. As property developers move further into snake habitats, the potential for human-snake encounters in the US is increasing. But experts say that simply killing every snake that winds up on human property isn't just unethical; it could also cause a range of environmental problems too, as Chris Baraniuk reports. Hear from US organisations that are working to capture native snakes and relocate them alive. Read more