Â鶹´«Ã½

THOSE who deny our role in climate change claim that the existence of a medieval warm period 1000 years ago somehow undermines concerns about global warming. It puts them in perspective, for sure, but far from belittling them, it exposes humanity’s vulnerability to the planetary thermostat, says Brian Fagan. The northern hemisphere warmed by about 1 °C – enough to nurture bumper harvests in Europe. That rise also brought mega-droughts to North America, and the collapse of both the Tang dynasty in China and the Mayan civilisation in central America. Fagan is a great guide. His canvas may be smaller…