In contrast, the evidence examined in this Review confirms that “business as usual” is not an option. Attempts to continue along the current unsustainable pathway will increasingly be thwarted as melting ice-caps, higher temperatures, heavier storms, longer droughts, more frequent floods and rising sea levels exert an ever heavier toll of wellbeing and lives. Ignoring the problem will undermine our standard of living, and eventually harm economic growth.

Unabated climate change risks raising average global temperatures by over five degrees — equivalent to the difference between now and the last Ice Age. This would take humankind into uncharted territory. The higher the average temperature, the greater the risk of irreversible ecological changes and amplifying destructive impacts. Such changes would transform the physical geography of the planet, as well as the human geography — how and where we live our lives.

Alongside mitigation to reduce emissions, we also have to encourage adaptation, or action to limit the damage caused by the climate change already built into the global ecosystem by past emissions.

Eventually the world will run out of the carbon-based fuels that cause the problem. If we continue to use them on a ‘business as usual’ basis, however, the world will be irretrievably damaged well before they are exhausted. For this reason, the rapid development of carbon capture and storage technology is essential to reconcile the continued use of fossil fuels, particularly coal, with climate change objectives.

... contd.