How much has urbanisation affected United Kingdom temperatures?

Abstract

This study aims to estimate the affect of urbanisation on daily maximum and minimum temperatures in the United Kingdom. Urban fractions were calculated for 10 km × 10 km areas surrounding meteorological weather stations. Using robust regression a linear relationship between urban fraction and temperature difference between station measurements and ERA-Interim reanalysis temperatures was estimated. For an urban fraction of 1.0, the daily minimum 2-m temperature was estimated to increase by 1.90 ± 0.88 K while the daily maximum temperature was not significantly affected by urbanisation. This result was then applied to the whole United Kingdom with a maximum Tmin urban heat island intensity (UHII) of about 1.7K in London and with many UK cities having Tmin UHIIs above one degree. This paper finds through the method of observation minus reanalysis that urbanisation has significantly increased the daily minimum 2-m temperature in the United Kingdom by up to 1.70 K.