Warmer temperature prompts trees to release aerosols which in turn stimulate cloud formation. And that can help to cool the temperature, at least modestly.

Renewable energy is rapidly becoming a much more serious possibility, as novel technologies come of age and offer the prospect of a new relationship between Africa, the Middle East and Europe.

German researchers have found a way to overcome one of the problems with renewable energy – the fact that it is not always available – by linking different options in a unified system.