Unprecedented climate change

The speed and scale of man-made global warming is unlike anything our planet has experienced in at least 2,000 years, new research has found. The last two millennia have seen dramatic peaks and troughs in temperatures, including the Medieval Climate Anomaly, an unusually warm period, and the Little Ice Age (1300s to 1800s). But an analysis of 700 proxy records of temperature change—telltale geological signs in tree rings, ice cores, and sediment—from around the world showed that none of these events affected more than half the globe at any one time. The current warming, in contrast, has seen temperatures rise to record levels pretty much everywhere except Antarctica. Separate research concluded that many of the climate fluctuations from 1300 to 1800 were caused by volcanic eruptions, which threw vast quantities of ash into the atmosphere that reflected sunlight and cooled surface temperatures. Mark Maslin, a climatologist at University College London, tells Reuters.com that the research should “finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle.” ■