The document discusses several major environmental threats including lead poisoning in children, overfishing of sharks that can disrupt ocean ecosystems, overpopulation contributing to famine, deforestation, climate change evidenced by melting polar ice caps, and various forms of air and water pollution. Specifically in Spain, issues include deforestation from uncontrolled logging and fires, air pollution from industry ranked 20th globally, and water pollution from industry, agriculture, and oil tankers affecting both surface and coastal waters.