Relations between climate change and mass movement: Perspectives from the Canadian Cordillera and the European Alps

https://doi.org/10.1016/j.gloplacha.2021.103499Get rights and content

Highlights

  • Climate change is accelerating mass wasting in high mountains.

  • Deglaciation and permafrost degradation is the main driver of slope instability.

  • Regional differences are controlled by climate, topography and geology.

  • Integration of data from different regions can help fill knowledge gaps.

Abstract

Earth's climate is warming and will continue to warm as the century progresses. High mountains and high latitudes are experiencing the greatest warming of all regions on Earth and also are some of the most sensitive areas to climate change, in part because ecosystems and natural processes in these areas are intimately linked to the cryosphere. Evidence is mounting that warming will further reduce permafrost and snow and ice cover in high mountains, which in turn will destabilize many slopes, alter sediment delivery to streams, and change subalpine and alpine ecosystems. This paper contributes to the continuing discussion of impacts of climate change on mountain environments by comparing and discussing processes and trends in the mountains of western Canada and the European Alps. We highlight the effects of physiography and climate on physical processes occurring in the two regions. Processes of interest include landslides and debris flows induced by glacier debuttressing, alpine permafrost thaw, changes in rainfall regime, formation and sudden drainage of glacier- and moraine-dammed lakes, ice avalanches, glacier surges, and large-scale sediment transfers due to rapid deglacierization. Our analysis points out the value of integrating observations and data from different areas of the world to better understand these processes and their impacts.

Introduction

Few scientists now question the conclusion drawn by the Intergovernmental Panel on Climate Change that Earth's climate is rapidly warming and will continue to do so through the remainder of this century (IPCC, 2013, IPCC, 2018). Environmental changes that are being driven by our changing climate are diverse and large, and the supporting evidence is compelling, but the full extent, timing, and magnitude of the response of the Earth surface to climate change are plagued with uncertainty. In many cases and in most areas, we lack systematic, reliable, and pertinent data over sufficiently long periods to assess and quantify these changes (Knight and Harrison, 2012; Cramer et al., 2018). Moreover, although climate change at the global scale has been reasonably well documented, regional and local changes are more poorly known and much more difficult to forecast (Pielke Sr. and Wilby, 2012; Sutton et al., 2015; Schwingshackl et al., 2018). Finally, the response of many environmental processes to climate change may be delayed and may display non-linear behavior, further complicating understanding and forecasting (Wegmann et al., 1998; Viles and Goudie, 2003; Pelletier et al., 2015).

Changes in atmospheric circulation patterns and in the interplay between oceans and the atmosphere are driving changes in local and regional precipitation and temperature that are, in turn, impacting the stability of slopes, the amount and seasonality of water transfers out of mountains, and sediment transfers by periglacial, fluvial, and mass wasting processes (Haeberli, 2005; Liu et al., 2008; Moore et al., 2009; Gariano and Guzzetti, 2016; Majone et al., 2016; Huss et al., 2017; Beniston et al., 2018).

Natural surface instability reflects disequilibria of processes and systems, and is expected to increase as climate changes (Schmidt and Dikau, 2004; Lewkowicz and Harris, 2005; Jakob and Lambert, 2009; Keiler et al., 2010; Huggel et al., 2012; Haeberli, 2013; Gobiet et al., 2014; Deline et al., 2015; Arnell and Gosling, 2016; Dietrich and Krautblatter, 2017; Ravanel et al., 2017; AghaKouchak et al., 2020). In this context, manifestations and trends of natural instability are not only consequences of climate change, but also provide data for assessing and quantifying that change (Borgatti and Soldati, 2010; Pánek, 2019).

This paper contributes to the ongoing discussion of impacts of climate change on environments and physical processes in high glacierized mountains. The key intermediary between climate on one hand and montane environments and processes on the other is the cryosphere, which is rapidly responding to warming through loss of glacier ice, snow, and permafrost (Evans and Clague, 1994; Zemp et al., 2006; Gruber and Haeberli, 2007; Harris et al., 2009; Bolch et al., 2010; Romanovsky et al., 2010; Brown and Robinson, 2011; Haeberli, 2013; IPCC, 2013, IPCC, 2019; Huss et al., 2017; Beniston et al., 2018; Guglielmin et al., 2018; Menounos et al., 2019). Our focus is the mountains of western Canada and the European Alps, which are the mountain regions that we are most familiar with. These two areas share many common features, but also have marked climatic, geologic, and physiographic differences that provide context for a discussion of the processes affecting the world's mountains. A comparative analysis of processes and trends in the two study areas facilitates an understanding of contemporary alpine landscape dynamics and the ability to forecast impacts of future climate change in mountains.

Section snippets

Western Canada

The Cordillera of western Canada is part of the great belt of mountains that forms the western margin of the Americas. Within Canada, this belt is up to 900 km wide, more than 2000 km long, and includes most of British Columbia and Yukon, and parts of Alberta and District of Mackenzie, an area of about 2,000,000 km2 (Fig. 1a). The population of the region is only five million people, a little over 30% of the population of the European Alps. Most of these five million people live in cities

Climate change over the past century

Globally averaged temperature data indicate that Earth's atmosphere at the planet's surface has warmed an average of 0.85 °C above the average for the period 1880–2012 (IPCC, 2013). Warming has accelerated in the past three decades, each of which has been successively warmer than any prior decade since 1850: the past five years (2015–2019) are the five warmest on record, and global mean temperatures in 2019 were 1.1 ± 0.1 °C above pre-industrial levels (Fig. 2; World Meteorological

Changes in the cryosphere

The cryosphere, comprising snow, glaciers, and permafrost, integrates climate variations over a range of time scales, making it a natural sensor of climate variability (Kääb et al., 2007). The Greenland and Antarctic ice sheets have been losing mass over the past several decades, and alpine glaciers have continued to shrink worldwide (Zemp et al., 2017); the rates of early 21st-century mass loss are without precedent (Zemp et al., 2015). Snow cover responds most rapidly to climate change. It

Climate and slope instability

Slope instability results from a complex interaction among geology, topography, climate, vegetation, and land use. Time is also a significant factor because the stability of most slopes deteriorates slowly due to gravitational and other forces (Ballantyne, 2002; Alberto et al., 2008; Phillips et al., 2017; McColl and Draebing, 2019).

Climate contributes to slope failure both as a cause and as a trigger. As a causative factor operating over a long period, climate shapes Earth's surface and works

Cryosphere degradation and slope instability

The suggestion that climate warming is reducing the stability of mountain slopes stems from an argued increase in the number of moderate to large landslides at high elevations in the Alps over the past century (Fischer et al., 2006; Gruber and Haeberli, 2007; Ravanel and Deline, 2011; Deline et al., 2015; IPCC, 2019; Viani et al., 2020); and similar arguments have been made in western Canada (Geertsema et al., 2006a). Several processes can act separately or jointly to cause slopes to fail at

Effects of recent changes in precipitation on slopes

Hillslopes respond in different ways to changes in precipitation. Although increased rainfall generally reduces slope stability, the response differs considerably depending on lithology, structure, discontinuities, slope geometry, and other factors, which in some cases can be more important than climate change in controlling landscape sensitivity to landsliding (Schmidt and Dikau, 2004).

Landslides can have rapid or delayed responses to changes in precipitation (Gariano and Guzzetti, 2016).

Changing mass movement hazard in a warming world

Earth's atmosphere is warming, although the amount of warming differs from region to region. Warming alone may have little direct effect on the stability of slopes in mountains without glaciers or permafrost, although it influences vegetation and can increase evapotranspiration. Increased evapotranspiration may reduce soil water and increase the stability of near-surface sediments. In contrast, rising air temperatures can destabilize slopes in presently glacierized or recently deglaciated areas

Research gaps

A better understanding of impacts of climate change on slope stability requires that we address knowledge deficiencies, the foremost of which are the following:

  • 1)

    More research is needed on possible links between landslides and ocean-atmosphere interactions. In the Canadian Cordillera, the Pacific Decadal Oscillation (PDO) strongly influences temperature and precipitation patterns in cycles that in the past have spanned 20–30 years. The warm phase of the PDO that started in 1976 was a period of

Conclusions

Evidence is mounting that our changing climate is impacting the stability of slopes in mountain ranges around the world. Nevertheless, the spatial and temporal links between landslides and patterns of temperature and precipitation change remain poorly understood. Establishing and understanding these links are difficult for several reasons. First, climate change is highly variable in time and space. Second, downscaling of climate models to the local scale is fraught with difficulty, and

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Fig. 4 was drafted by Richard Franklin. We thank the Editor and anonymous reviewers for their valuable comments that helped to improve the original manuscript.

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