Sir David Attenborough has warned that life will get tougher for future generations as they battle the effects of global warming - and revealed how the "natural world" had helped him cope with grief.

Demographers aren't known for their sense of humor, but the ones who work for the United Nations recently announced that the world's human population will hit 7 billion on Halloween this year. Since censuses and other surveys can scarcely justify such a precise calculation, it's tempting to imagine that the UN Population Division, the data shop that pinpointed the Day of 7 Billion, is hinting that we should all be afraid, be very afraid.