Guardian: As part of an institution that is raising the alarm about the future of the planet, you would expect Didier Houssin, director of sustainable energy policy at the International Energy Agency (IEA), to be gloomy. "Scaring people is not always a good strategy," he says. "It's important to explain that there are solutions, the future is not hopeless." He concedes that the situation "is not rosy", but "there are some positive examples and we need to learn from them". Some clean technologies are progressing...