Three factors which may be driving the sharp increase in melanoma incidence globally over the last 100 years:

1.  Cultural and or fashion changes Less covering up with clothing.
2.  The ozone-layer. Depletion of the ozone layer, increasing UV index
3. Climate change. Different continents increasing in temperature/less clothing

The following four factors which may contribute to the higher relative incidence of melanoma in Australasia:

A higher incidence in Australasia is recognised due to migration since colonisation over the last 250 years. Populations of light skinned individuals have geographically translocated from low UV index regions to a country with regular, high daily UV index readings. Proximity to the equator, the earth’s orbit around the sun, less pollution and clear skies.

Reference:

1. Rosendahl, C. (2020, February). Course textbook Core Knowledge and Professional
   Practice, Chapter 6 [PDF Document]. The University of Queensland
2. Rosendahl, C. (2018, June). Course textbook Core Knowledge and Professional Practice,
   Chapter 9 [PDF Document]. The University of Queensland
3. Connell, A. (2021). IMED7003 [PowerPoint assessed discussion board Case 3]. IMAGE CREDIT.