Our correspondent first asked co-author Christopher Flavin what constitutes economic unsustainability. For example, the energy system is based on fossil fuels which are limited in nature and which are adding to greenhouse gases in the atmosphere. None of that can go on indefinitely without eventually collapsing the economy itself. Flavin was then asked what are the main signs of global environmental decline. Second, we've seen a massive die-off in coral reefs around the world, which are very sensitive to rising ocean temperatures.
Coral reefs are the tropical forests of the oceans.
They're really the base of the ecological support system. And third, we have an entire chapter on the decline of the amphibians, a very important life form which is very environmentally vulnerable. Almost anywhere in the world where scientists have looked, they've found that many amphibian populations are either in decline or in many cases have disappeared entirely. Flavin was asked to discuss what he considered to be realistic, large-scale alternatives to reduce the world's dependence on fossil fuels. The challenge now is to move from the carbon-dominated energy system of the 20th century to a hydrogen economy during the course of the 21st century.