Influence of North Pacific decadal variability on the western Canadian Arctic over the past 700 years

Abstract

Abstract. Understanding how internal climate variability influences arctic regions is required to better forecast future global climate variations. This paper investigates an annually-laminated (varved) record from the western Canadian Arctic and finds that the varves are negatively correlated with both the instrumental Pacific Decadal Oscillation (PDO) during the past century and also with reconstructed PDO over the past 700 years, suggesting drier Arctic conditions during high-PDO phases, and vice versa. These results are in agreement with known regional teleconnections, whereby the PDO is negatively and positively correlated with summer precipitation and mean sea level pressure respectively. This pattern is also evident during the positive phase of the North Pacific Index (NPI) in autumn. Reduced sea-ice cover during summer–autumn is observed in the region during PDO− (NPI+) and is associated with low-level southerly winds that originate from the northernmost Pacific across the Bering Strait and can reach as far as the western Canadian Arctic. These climate anomalies are associated with the PDO− (NPI+) phase and are key factors in enhancing evaporation and subsequent precipitation in this region of the Arctic. Collectively, the sedimentary evidence suggests that North Pacific climate variability has been a persistent regulator of the regional climate in the western Canadian Arctic. Since projected sea-ice loss will contribute to enhanced future warming in the Arctic, future negative phases of the PDO (or NPI+) will likely act to amplify this positive feedback.

Flowpath and retention of snowmelt in an ice‐covered arctic lake

“…Discharge and penetrative convection depend on processes which will change in a warming climate but not necessarily in ways that are predictable now (Lapointe et al ). The onset of penetrative convection depends on ice thickness, which is likely to become less in arctic lakes as precipitation and air temperatures increase in winter.…”

Evolution of palaeo‐sea‐surface conditions and sediment dynamics over the last 2700 years on the Mackenzie Slope, Beaufort Sea (Canadian Arctic)

“…MacDonald & Case 2005;Barron & Anderson 2011;Anderson et al 2016;Deschamps et al 2019) suggest that variations in precipitation in western North America could be controlled by changes in large-scale ocean-atmosphere climate modes, similar to the modern PDO and AO. Indeed, warmer temperatures in the central North Pacific during the PDO-like conditions and a western weak AL induce southerly wind anomalies (due to variations in sea level pressure), which extend across the Bering Strait, increasing heat and moisture transport to the western Canadian Arctic (Lapointe et al 2017), including the Yukon Territory and the northern part of the Mackenzie Basin (Figs 10, 11A; Hook et al 2015;Deschamps et al 2019). Within this context, our results suggest that prevailing PDO-conditions probably promoted enhanced precipitation and thus major remobilization of flood-plain sediments in the northern part of the Mackenzie Basin during this period.…”

Arctic hydroclimate variability during the last 2000 years: current understanding and research challenges

“…A continuous wavelet transform (CWT) allows for the decomposition of a non-stationary time series that contains periodic or aperiodic components, noise, and progressive or abrupt changes (progressive transitions, singularities, and breaks; Debret et al, 2007;Steinhilber et al, 2012;Lapointe et al, 2017). The resulting plot of the wavelet transform, the scalogram, is a frequency contour diagram with time on the x axis, frequency, wavelet scale, or equivalent Fourier period on the y axis, and power on the z axis.…”