Hurricane Harvey has taught us many lessons, but the most valuable may be the oldest lesson of all, one we humans have been learning – and forgetting – since the dawn of time: how much we all have to lose when climate and weather disasters strike.

The risks we face from disasters depend on three factors: hazard, exposure and vulnerability. In the case of Harvey, the hazard was the hurricane with its associated winds, storm surge and, most of all, rain. Houston is one of North America’s biggest metro areas, making 6.6 million people exposed to this hazard. Finally, there’s our vulnerability to heavy rainfall events, in this case exacerbated by the city’s rapid expansion that has paved over former grasslands, overloaded critical infrastructure, challenged urban planning and limited evacuation routes. These three factors explain the immense costs associated with tragedies like Hurricane Harvey.

As atmospheric scientists in Texas, we already know the hazards are real. Once the effects of Harvey have been added up, Texas and Louisiana will have been hit by more billion-plus dollar flooding events since 1980 than any other states.

We also know that many of these hazards are intensifying. In a warmer world, heavy precipitation is on the rise, which increases the amount of rain associated with a given storm. Sea level is rising, worsening the risks of coastal flooding and storm surge. At the cutting edge of climate research, scientists are also exploring how human-induced change may affect storm intensity and the winds that steer the hurricanes.

This is why catastrophes like Harvey – in which every extra inch of rain can lead to additional damage and harm – highlight exactly how and why climate change matters to each and every one of us.

Read our full essay at The Conversation.