system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does lighter skin get sunburnt more than darker skin if white reflects sunlight and black absorbs it? Shouldn't darker skin get sunburnt more than lighter skin?
gpt
What causes sunburn is not just absorption of light somewhere in the skin, but rather absorption of light by DNA spcifically. Damage to DNA can result in cancer, which is why in case of sunburn the damage is detected by the cell, causing cell to commit suicide (to reduce risk of cancer). Dead cells will cause sunburn, but that is far better than cancer.

Dark skin has protein (melanin) that absorbs sunlight (actually, light skin has it too, but darker skin means much greater amount). That absorption results in a far lower chance of light reaching DNA and being absorbed by it. The protein then releases that energy as heat, which can be managed by just keeping the body cool. Even if a given melanin molecule gets damaged, it has no impact - since it is not damage to DNA it does not result in risk of cancer, o no need for cell to suicide, just make a new melanin molecule.

Also, note that sunburn-causing suicide mechanism is imperfect, so someone who habitually gets in situations where they are sunburnt is at higher risk of skin cancer. So, use sunscreen.