Tens of thousands of Californians are turning to a crowdsourced, nonprofit app called Watch Duty for critical, up-to-the-moment disaster updates as deadly fires continue to rage through the state. The app, which uses a mixture of official government and volunteer data to track wildfires, surpassed OpenAI’s ChatGPT and Meta’s Threads as the most downloaded app on the Apple App Store on Wednesday. Social media users have encouraged residents in affected areas to download the app in order to track the fire’s rapid movements and stay aware of possible evacuation orders. Apps like Watch Duty, which have seen a surge in interest in recent years, may become even more important as climate change-related natural disasters intensify in scope and scale. LA people, download the Watch Duty app! It gives you updates on fires nearby, evacuation notices, and even will show you where an evacuation center is if you need to evacuate! stay safe everyone! pic.twitter.com/vWt7uqNAf5— e taylor (@erinisaway) January 7, 2025 As of Thursday, at least five people had died from the California fires, and more than 2,000 homes and businesses had been destroyed or damaged, according to The Los Angeles Times. More than 130,000 people from Los Angeles and Ventura counties have been ordered to evacuate. There seems to be no immediate relief in sight. Warnings remain in effect for much of LA and Ventura County throughout Thursday. The cause of the fires is still under investigation.  How the app works  The Watch Duty app shows users a map with flame icons denoting areas where fires are blazing. Users receive near real-time information on a fire’s trajectory as well as updates from government officials and any evacuation orders. In addition to official government accounts, the app also pulls in data from wildfire cameras, satellite images, and vetted 911 calls. A team of roughly 200 “citizen reporters”—which include retired and active firefighters, journalists, and emergency responders—rapidly comb through that material and then send it to users through the app. The app makers say this combination of multiple data sources and rapid vetting makes it more reliable than often chaotic, social media sources and more immediately useful than government sources.  [ Related: This app is helping Californians stay on top of wildfire risks ] Screenshot: Popular Science As Popular Science previously reported, Watch Duty was founded in 2021 by a California software engineer named John Mills who himself had experience evacuating from a fire. Mills took a wildland firefighting course and said he quickly saw a gap in communication during disaster events. Watch Dutch was launched to fill that gap. Mills told Popular Science the app gained 22,000 users within two days of its release. That number swelled to 80,000 in less than a month. Watch Duty said it had  ended 2024 with 7.2 million users a figure up from just 1.9 million a year prior. This week, as fire rages, the app reportedly had more than 600,000 new users in just 24 hours.  “We just want to give people peace of mind and give them information so they can make informed decisions,” Mills said. “It is not complex by design. It’s very simple, it’s very easy to operate.” While the app pulls from a variety of information sources, Nick Russel, the app’s vice president of operations, told NBC News it also maintains direct communication with official agencies in 22 states. These officials can help make sure the rapid information being pushed through the app is accurate and high quality. “One of the big things for us, our big theme, is quality over quantity. We’re not in a big hurry to get information that we’re going to have to go and retract later,” Russel told NBC News this week. “And so if it takes a few extra minutes to get it out there, that’s fine, but we want it to be that official info.”  Watch Duty isn’t just for fires  Watch Duty is currently focused on tracking wildfires but the app’s developers have plans to expand its remit this year. In a recent blog post, Watch Duty said it’s looking to expand its services to include flooding alerts as well as threshold-based wind alerts and weather events that can make wildfires worse.  “From day one, we knew that wildfire was just our beachhead and our name represents just who we are—seemingly ordinary residents who stay up late on “watch duty” during a disaster,” Watch Duty wrote in a blog post.  “This will be the year when our community discovers why our organization is not called ‘Fire Duty’ the blog post added.  That expansion to other natural disasters could prove critical in coming years as more parts of the world are expected to feel the impact of the increase in extreme weather events amplified by climate change. Annual greenhouse gas emissions reached an all-time high last year and have led to an overall uptick in global temperatures. A United Nations report released late last year said the world is currently in a “climate crunch time.”  Apps like Watch Duty may inevitably become more common companions for people as a range of dangerous weather events, from fires and floods to stronger hurricanes, go from remarkable to common. The post This crowdsourcing app is a lifeline for Californians tracking wildfires appeared first on Popular Science.