Nature Geosci. doi:10.1038/ngeo208 (2008)

Credit: BLICKWINKEL/ALAMY

Wind measurements have verified that the tropical upper troposphere is warming, and doing so most strongly just below where it meets the stratosphere.

The absence of this warming on decadal timescales as recorded by thermometers on weather balloons and by satellites has been a mystery to climate modellers and seized upon by global-warming sceptics. Robert Allen and Steven Sherwood of Yale University in New Haven, Connecticut, calculated horizontal gradients in temperature from vertical wind gradients since 1970. The temperature record is more muddied by non-climatic artefacts than that of wind because the temperature-measuring instruments used are difficult to calibrate and have varied in quality over the years. The pattern the authors found agrees with expectations derived from current climate models.