The fall of fall

摘要

John keats described a "season of mists and mellow fruitfulness". Nat King Cole sang of "autumn leaves of red and gold". But what if the leaves cease to turn red and gold, and the mellow fruits don't cling on until the arrival of autumn mists? Howard Neufeld of Appalachian State University in Boone, North Carolina, is one researcher who thinks this may be so. He says the curtain may be descending on one of the season's defining spectacles, the fiery spread that sweeps through the forests of New England each fall - and climate change is to blame. "Warmer falls reduce the intensity of the red colours - of sugar maples especially, the mainstay of colour in the north-east of the US," he says. It's all down to how warmer autumn nights tweak the internal chemistry of leaves: they cause sugar levels to drop, which in turn affects the pigments responsible for those signature reds. Sadly, russet tones are not the only autumn tradition at risk, although amid the losers there could be surprise winners as well.