The horrific images of people trapped in a subway train being rapidly submerged by floodwaters in the Henan provincial capital, Zhengzhou, will stay with many of us the rest of our lives. Their videos and messages posted online frantically calling for help were quickly heeded and hundreds rescued, but a dozen died as water filled the carriages. The death toll in and around the city of 12 million is more than 30 and damage is likely to run into billions of yuan, prompting inevitable debate as to whether the tragic toll could have been avoided. An investigation will no doubt lead to improvements in preparation and weather forecasting, but in an era where climate change is behind worsening storms and droughts, we always have to be alert and ready for the unexpected. Not for decades has so much rain fallen in so short a time in China. Zhengzhou was deluged by more than 200mm (7.9 inches) in just an hour on Tuesday and the equivalent of a year’s rainfall was recorded in a mere three days. Forecasters had predicted downpours, but were inaccurate about the timing and location of the worst precipitation. When they issued a red alert, the country’s highest warning, for the city, people were already on their way to work and caught off guard. Cars were swept away as roads were turned into raging torrents. Transport links were cut and power and water supplies disrupted, while tens of thousands of people had to be evacuated. Hong Kong considers using disaster relief fund to help Henan Dams overflowed and crops were ruined as land was inundated. President Xi Jinping called for all resources to be mobilised and military personnel, police and emergency workers were quickly involved in rescue and disaster relief efforts. Zhengzhou is on the Yellow River on a fertile plain in a region accustomed to seasonal heavy rain and floods. But rising temperatures from climate change are causing warmer waters in the Pacific Ocean, leading to more extreme weather. But for all the improvements in forecasting, such systems remain difficult to predict with accuracy; it is also impossible to determine how much rain will fall at a given time the following day. Despite using satellites and supercomputers, the National Meteorological Centre’s rain estimates are more often wrong than right. As technology improves, so will forecasting. Drones were deployed to help with communications and rescue work. The largest hi-tech companies, accused of putting profits ahead of social responsibility, have donated about 1 billion yuan (US$154 million) for the relief effort. Hongkongers are also stepping forward with donations as they have often done when there have been natural disasters on the mainland. There is now greater awareness among Chinese of the impact of climate change . Had warnings been taken more seriously and everyone better prepared, the losses in Henan could have been reduced.