Monday, 10 January 2005: 4:15 PM
Large scale warming confirmed by temperatures in windy weather
Controversy has persisted over the influence of urbanisation on reported large-scale temperature trends. However, urban warming and other local thermal influences are reduced in windy conditions. So daily land surface air temperatures since the mid-twentieth century from a selection of stations worldwide have been analysed separately for windy and nearly calm conditions as well as for the full sample. We find that, globally, the trends in temperature are almost unaffected by this sub-sampling, indicating that the observed overall warming is not a consequence of urban development or other local or instrumental influences. A small tendency for windy days to have warmed more than other days in winter over Eurasia is the opposite of that expected from urbanisation and is likely to be a consequence of atmospheric circulation changes. This study has benefited from improved availability of data from the Global Climate Observing System, but major gaps remain in the tropics.