Emerged as a major issue in the 20th century in the face of increasing evidence that pollution, uncontrolled use of natural resources, and population growth were putting increasing pressure on the long-term sustainability of these resources.

protection of air, land, water, biodiversity, and the renewable natural resources

Explanation:

Due to the urbanization and also the advancement of the technology in the 20th century, many natural resources like air, water, land and biodiversity started to get exploited.

There is the increase in the levels of the pollutants in air and water and land is being degraded. There is non stop use of the natural resources and not taking the care of their sustainability.

Thus protection of these natural resources emerged as a major issue then.

d.summerains, the last one