I watched a movie back in the late 1990’s or early 2000’s. The ozone layer has finally been completely destroyed, allowing massive amounts of solar radiation to scorch the planet. Mankind is barely surviving in small pockets. Being exposed to direct sunlight for more than an a few minutes will leave a person with extremely severe sunburn, longer exposure results in death.
The movie focuses on a group of teens attending high school in their community. The main character is an older teen boy being picked on by the popular kids and jocks. The main teen lives alone in his house because his scientist parents disappeared years ago. The landscape outside is barren wasteland, but inside his house is lush jungle growth to the point that you can barely see the walls or floors.
At one point, main teen gets tied up and left outside to die from exposure. He’s outside for many hours before his friends find him, but to everyone’s surprise he’s only moderately sunburned instead of dead. Later in the movie you find out that his parents genetically modified his DNA at birth to be radiation-resistant.
Back at his house, he learns that his parents never really disappeared; they had actually changed themselves (somehow) into two clouds of firefly-like insects. They were still living in the house but for whatever reason never communicated with him.
By the end of the movie, the house bursts open and the lush jungle growth starts spreading. The plants inside had been genetically engineered by mom and dad to be radiation-resistant and are thriving in the outdoors.