Urbanization and seasonal temperature trends: observational evidence from a data‐sparse part of North America

Abstract

AbstractViewed from the continental or hemispheric perspective, the evidence of warming trends in surface temperatures continues to accumulate. Here, we focus on the detection of seasonal temperature trends at regional and sub‐regional space scales. The study region is transnational, extending from the border areas of New Mexico and Texas in the USA, southward into the altiplano of north central Mexico. The analysis considers maximum and minimum temperature records (1941–2000) from 21 stations located in a variety of land‐use environments ranging from large urban settings to rural areas. The analysis demonstrates that a significant part of the variability in minimum temperatures for stations located in large urban areas is captured by positive linear trend, and thus is likely associated with rapid urbanization within the region. A similar, but comparatively minor, urban effect is also apparent in the maximum temperature records for the warm season (June–September). Aside from the urban influence, the most consistent feature emerging from the analysis is the tendency for station records to exhibit a recent (post—1970) warming trend. It is present across all place sizes, i.e. from large urban to rural stations, and is particularly pronounced for cool‐ and warm‐season minimum temperatures and for warm‐season maximum temperatures. This behaviour generally mirrors the temperature trends detected on continental and hemispheric space scales, and thus the onset of this warming regime is broadly consistent with documented changes in large‐scale climate modes such as the North Atlantic oscillation and the Atlantic multi‐decadal oscillation. Copyright © 2003 Royal Meteorological Society