Jan 29, 2015

Changes in observed climate extremes in global urban areas

by
Vimal Mishra, Auroop R Ganguly, Bart Nijssen, Dennis P Lettenmaier
,
Environmental Research Letters
  • Uses observed station data for 217 urban areas across the globe, and shows that these urban areas have experienced significant increases (p-value <0.05) in the number of heat waves during the period 1973–2012, while the frequency of cold waves has declined
  • Finds almost half of the urban areas experienced significant increases in the number of extreme hot days, while almost 2/3 showed significant increases in the frequency of extreme hot nights
  • Finds extreme windy days declined substantially during the last four decades with statistically significant declines in about 60% in the urban areas
  • Finds significant increases (p-value <0.05) in the frequency of daily precipitation extremes and in annual maximum precipitation occurred at smaller fractions (17 and 10% respectively) of the total urban areas, with about half as many urban areas showing statistically significant downtrends as uptrends
  • Finds that changes in temperature and wind extremes, estimated as the result of a 40 year linear trend, differed for urban and non-urban pairs, while changes in indices of extreme precipitation showed no clear differentiation for urban and selected non-urban stations