The recent hiatus in global warming of the land surface: Scale‐dependent breakpoint occurrences in space and time

Abstract

AbstractThe spatial and temporal variability of the recent land warming hiatus have seldom been explored, despite their importance for understanding the mechanisms underlying the phenomenon. In this study, we applied piecewise linear regression to investigate the spatiotemporal patterns of the breakpoint time of warming over 40 years (1974–2013). Our results showed that at the global scale, mean annual temperature (MAT) over the land increased significantly until 2005 and that the warming trend then stalled. However, the breakpoint time of the warming varied greatly among different seasons and continents. We found no statistically significant breakpoint in MAT over the Northern Hemisphere, but MAT over the Southern Hemisphere showed a significant breakpoint (P < 0.001) in 1979. At the seasonal scale, only the winter season (December‐January‐February) showed a statistically significant breakpoint in global land temperature. The other seasons showed continuous increasing temperature during the whole study period. Our study examined the recent global warming hiatus on the land surface using an area‐weighted summary of a scale‐dependent phenomenon with substantial spatiotemporal heterogeneity and revealed the winter cooling in the Northern Hemisphere low‐middle latitudes in 1999–2008 as the major contributor to the global warming hiatus on land surface in 2005. This result highlights the importance of using a statistical method to identify the timing of climate phase change. A better understanding of the processes behind the spatiotemporal patterns of local‐scale breakpoint occurrences in land surface temperature would shed new light on the mechanisms of the recent global warming hiatus.