 CaROLINE LUCaS, Britain's only Green MP, wants a return to the "wisdom" of the wartime generation to fight climate change, the recession and obesity.  During an impassioned debate in the Telegraph Tent at Hay, she said the ethos of "Keep Calm and Carry On" had helped a generation through the difficulties of the Second World War. In the same way, she said the current generation must work together to fight climate change.  "Climate change is a matter of security," she said. "Carbon rationing has to be part of the solution, which means investment in public transport, learning to make do and mend and saving fuel."