The study looked at how cities can get really hot in the summer, making it hard for people to stay cool. By using satellite data, the researchers found that Beijing has been getting hotter over the past 10 years, especially in the city compared to the countryside. The city's heat island has been growing bigger too. More buildings, people, and money in an area make it even hotter. This information can help city planners make better decisions about how to design cities in the future.