Sunlight protects us from other more serious cancers — probably all of them, but certainly the big ones such as colon, prostate and breast. William Grant, formerly a climate scientist with NASA, has shown that the more sunlight there is where you live (in the USA) the less your risk of developing these cancers. He estimated that 23,000 Americans died unnecessarily each year from these cancers due to lack of sunlight.
98% of skin cancers are not melanomas, they are forms known as squamous cell and basal cell carcinomas. These are clearly linked to UV exposure, but they are rarely fatal because they can be detected so early. Back in 1936 a paper in the Lancet even suggested that we should give people these treatable kinds of cancers in order to protect them from the more deadly internal cancers. I’m not advocating this, but it would probably work.

Sunburning,when the skin goes red and perhaps sore, contributes to all skin cancers (but in a complex way) while suntanning probably protects against both skin cancers and cancers of internal organs such as bowel and breast. On balance the sun probably prevents many more cancers than it causes.

Environmental pollution is emerging as another likely cause of melanoma. After the Seveso incident in 1976, when large amounts of dioxins were released into the atmosphere in northern Italy, the local melanoma rate rose more than 10-fold.