Characterizing the role of natural and forced air temperature variability in the Labrador region of northeastern Canada

English Abstract:

Air temperatures in the Labrador region of northeastern Canada are particularly sensitive to ocean-atmospheric telleconnections due to the region’s proximity to the Labrador Current and its position near the Canadian Polar Trough. Instrumental and paleoclimate reconstructions show pronounced multidecadal variability in regional air temperatures over the past several centuries highlighting the importance of unforced and forced variations in the region’s climate. Throughout much of the past century, air temperatures in Labrador remained fairly stable albeit with multidecadal variations. However, over the past 20 years regional warming has accelerated rapidly according to both instrumental and satellite datasets. Recent winter positive anomalies, in particular, have had negative impacts on the region’s aboriginal populations who rely on ice and snow for accessing traditional grounds. Coupled with the strains of living in an isolated northern environment, recent warming has challenged the adaptive capacity of communities to cope with recent environmental change.

Expanding upon recent work by Way and Viau (in press - Theoretical and Applied Climatology) this paper provides a detailed examination of the main drivers of regional climate variability over both long and short timescales. We show that rapid regional warming over the past two decades is linked to both natural and anthropogenic factors with several anomalously warm years related to recent anomalies in the Arctic Oscillation (AO) and North Atlantic sea surface temperatures (AMO). This contribution also provides a comparison with another recent climate analysis of Labrador by Finnis and Bell (in press - Canadian Geographer) showing that certain data selection choices in the latter study exaggerated the role of natural variability in recent warming. In comparing with future climate scenarios, our results suggest that the anomalously warm conditions observed in 2006 and 2010 are similar in magnitude to climate conditions projected for the mid-21^st century under high emissions scenarios (i.e. RCP 8.5). The largest sources of uncertainty in projecting regional climatic changes appear to result from differences between the various emission scenarios and the variability in North Atlantic sea surface temperatures.