Observed regional climatic changes over Ontario, Canada, in response to global warming

ABSTRACT Human‐induced climatic changes are not expected to be uniform across the globe due to the regional variations in topography, land cover/land use, economic development and so on. Investigating the regional effects of climate change is thus of great concern for decision makers and resource managers to develop scientifically informed policies and strategies against the changing climate. In the present study, regional climatology over Ontario, Canada, and its temporal trends in the past century are analysed based on the historical observations at the gauged stations, aiming to investigate how the local climate has been affected by human‐induced global warming. The analysis shows that the annual mean temperature over Ontario varies mainly between 1.6 and 7 °C with a median of 3.8 °C, while its annual total precipitation usually ranges between 836 and 1004 mm with a median of 896 mm. Further correlation analysis suggests that no or negligible correlations between total precipitation and mean temperature are found at the vast majority of stations (accounting for over 80% of the total), except for summer when significant negative correlations (with a correlation co‐efficient varying between −0.7 and −0.2) are reported at over 54% stations. As for the temporal trends, significant warming trends are detected throughout the province and the overall trend in annual mean temperature varies largely between 0.01 and 0.02 °C year –1 . Increasing trends in annual rainfall (by 1–3 mm year –1 ) and total precipitation (by 1–4 mm year –1 ) are detected at the vast majority of gauged stations, but no significant trends in annual snowfall are identified at most of the stations. The results of this study can help better understand the regional climate of Ontario and provide important references for developing future climate scenarios that can be used for impact studies.