Changing Cold Environments: A Canadian Perspective

By Hugh M. French and Olav Slaymaker

Changing Cold Environments; Implications for Global Climate Change is a comprehensive overview of the changing nature of the physical attributes of Canada's cold environments and the implications of these changes to cold environments on a global scale. The book places particular emphasis on the broader environmental science and sustainability issues that are of increasing concern to all cold regions if present global climate trends continue. Clearly structured throughout, the book focuses on those elements of Canada's cold environments that will be most affected by global climate change – namely, the tundra, sub-arctic and boreal forest regions of northern Canada, and the high mid-latitude mountains of western Canada. Implications are considered for similar environments around the world resulting in a timely text suitable for second and third year undergraduates in the environmental or earth sciences courses.

• Language: English
• Publisher: Wiley
• Release date: Oct 13, 2011
• ISBN: 9781119951087

Book preview

List of Contributors

The Editors

HUGH FRENCH taught at the University of Ottawa in the Departments of Geography (1967–2003), Geology (1982–1992) and Earth Sciences (1998–2003). He has broad experience of the cold non-glacial regions of the world. He is now Emeritus Professor, University of Ottawa and Adjunct Professor, Department of Geography, University of Victoria.

OLAV SLAYMAKER taught at the University College of Wales, Aberystwyth (1964–1968) and at the University of British Columbia in the Department of Geography (1968–2004). He is a geomorphologist interested in global environmental change. He has extensive experience of mountainous terrain and geomorphic systems. He is now Emeritus Professor, University of British Columbia.

Contributing Authors

DAVID BARBER holds the Canada Research Chair of Arctic System Science and is Director, Centre for Earth Observation Science, University of Manitoba. His research focuses on the causes and consequences of climate forcing of sea ice in the Arctic.

ROGER BARRY is former Director of the National Snow and Ice Data Center (NSIDC), in the Cooperative Institute for Research in Environmental Sciences (CIRES) and Distinguished Professor Emeritus in Geography, University of Colorado, USA. He has published 20 books and over 250 papers on Arctic and mountain climates, climate change and cryospheric science. He currently holds a Humboldt Prize Fellowship, 2009–2012.

CHRIS BURN holds the NSERC Northern Research Chair for Permafrost in the Yukon and Northwest Territories. He is Professor in the Department of Geography and Environmental Studies, Carleton University, Ottawa. He conducts field research in the Yukon and western Arctic Canada.

DAVID EVANS is Reader in Geography, Durham University, UK. He is a glacial geomorphologist who works in a wide range of glaciated landscapes, including Iceland, Arctic and western Canada, New Zealand and Northern Scandinavia. He has published widely on glacial landforms, glacial sedimentology and stratigraphy, and Quaternary palaeoglaciology.

KONRAD GAJEWSKI is Professor of Geography and Director of the Laboratory for Paleoclimatology and Climatology, University of Ottawa. He has published widely in the fields of arctic and subarctic paleoclimatology, paleoecology and paleolimnology.

JIM GARDNER is a physical geographer who has taught at the University of Waterloo and the University of Manitoba. He specializes in mountain geomorphology and hazards. He is now Adjunct Professor, Department of Geography, University of Victoria.

RICHARD KELLY is Professor, Department of Geography and Environmental Management, University of Waterloo and a group leader in the Interdisciplinary Centre on Climate change, University of Waterloo. His research interests are in snow and ice hydrology, especially the measurement of snow and ice from Earth-observing remote-sensing instruments

GITA LAIDLER is Assistant Professor, Department of Geography and Environmental Studies, Carleton University, Ottawa. Her research concerns the changes imposed on Inuit communities and their lifestyle by changing climate and associated environmental change. She works in Igloolik, Iqaluit and other northern settlements.

JENNIFER LUKOVICH is Research Associate at the Centre for Earth Observation Science (CEOS), University of Manitoba. Her research interests include the investigation of sea ice and atmospheric dynamics in the Arctic.

GLEN MACDONALD taught in the Department of Geography, McMaster University, 1984–1995, and is currently Director of the Institute of the Environment and Sustainability of the University of California Los Angeles, USA. He teaches in the UCLA departments of Geography and Ecology and Evolutionary Biology and conducts research on climate change, arctic and alpine tree lines, northern soil carbon and water resources.

JOHN POMEROY is Canada Research Chair in Water Resources and Climate Change and Director of the Centre for Hydrology, University of Saskatchewan. His research interests include snow hydrology, forest hydrology, frozen soils, and the hydrology of the mountains, prairies and northern Canada.

TERRY PROWSE is Professor of Geography, University of Victoria, and holds the Chair in Climate Impacts and Water Resources, University of Victoria. Current research interests include circumpolar cold regions hydrology and environmental effects of river ice.

MARK SERREZE is the Director of the National Snow and Ice Data Center (NSIDC) and Professor of Geography, University of Colorado, Boulder, USA. He has published extensively upon climate change and cryospheric issues.

MING-KO WOO is Emeritus Professor, School of Geography and Earth Science, McMaster University, and a professional hydrologist of the American Institute of Hydrology. He has conducted field studies in Canada and China, specializing in snow, permafrost, wetlands and water-related subjects.

Preface

Eighteen years ago we edited a volume called Canada's Cold Environments. It was a type of regional physical geography of northern Canada and its mountains. In its preface we set the tone by noting that ‘coldness is a pervasive Canadian characteristic, part of the nation's culture and history’. In spite of many indications that Canada has become a warmer place since 1993, coldness remains a pervasive and distinct Canadian characteristic. There is, however, sufficient change in the hydroclimate, and indeed in the ‘oekumene’ of Canada as a whole (those parts of Canada that are inhabited by permanent residents), to warrant a fresh look at Canada's changing physical environment. Moreover, the Canadian experience is a useful barometer against which similar changes in the other regions of the northern Polar World can be compared.

Whether or not the globe as a whole is experiencing a long term warming trend fuelled by increasing greenhouse-gas concentrations in the atmosphere or a cyclic and short term warming trend caused by geophysical drivers such as solar emission or changing Sun–Earth relations is a mega-problem upon which we are not willing or competent to comment. What we do know is that Canada's cold regions, and especially its arctic regions, are experiencing rates of warming that are unprecedented in the past millennium. We also know that human demands on the natural resources of Canada's cold regions are growing apace.

The most obvious changes relate to shrinking glaciers, reductions in annual sea ice extent, and longer duration of ice-free periods on rivers and lakes. These are physical realities that can be readily observed and measured. Others are more subtle. But these changes coincide with a period of increasing global demographic pressure and intensifying resource demand at a time when it is becoming clear that globalization is upon us. In addition, the sovereignty of Canada's Arctic may soon be questioned as the possibility of an ice-free sea route between Europe and the emerging economies of Southeast Asia becomes increasingly a reality. The net effect of these accelerating processes is to focus new and urgent attention on Canada's cold environments.

We have assembled 14 experts, in contrast with just nine in our earlier book. All have extensive Canadian experience. The new topics which now require separate chapter treatment are sea ice, river and lake ice, remotely sensed imagery and the ways in which the northern indigenous peoples (in this case the Inuit) interact with this rapidly changing environment. We have also given more space to ecological changes and provide deeper understanding of the glacial and postglacial histories of our cold environments. In this way we hope to counteract some of the more emotional responses to contemporary environmental change. It is our conviction that environments have always changed and continue to evolve. In fact, as a society, we can even be grateful for the rapid environmental changes of the last 2.5 million years (the Quaternary); many would argue that such changes have been partially responsible for stimulating the evolution of Homo sapiens. Thus, our emphasis upon current and future change indicates our own belief in our continued evolution.

In this volume we, and our contributors, have attempted to provide an authoritative, yet readable scientific statement about the nature of Canada's changing cold environments. We have not attempted a comprehensive geographic coverage. Instead, we have focused on the distinctive attributes of Canada's changing cold environments. Their temporal and spatial variability is central, as is the interaction of northern peoples with those environments. As in our earlier volume, the constraints and opportunities created by coldness for human activity are also considered.

We have both seen a progressive evolution of Canada as a pre-eminent cold-climate nation over the last 40 years. Thus, our objectives in undertaking an assessment of this change have been threefold. The first has been to provide insight into the ways in which biophysical processes are influenced by coldness at a range of scales. The second has been to provide a biophysical context for understanding the human geography of Canada. The third has been to examine current rates of environmental change and, if projected into the future, how those rates of change will affect Canada's cold environments.

We wish to thank the authors of the individual chapters for their willingness to join us in this venture and to share their experience and wisdom. Needless to say, not all of them provided material in a timely and efficient manner. But they have all achieved, in our opinion, the desired mix of authoritative information and accessible style. Our cartographers, Ole Heggen and Eric Leinberger, deserve special recognition for the quality of the figures and images.

Any lack of coherence and errors of fact or interpretation are our responsibility and we request your indulgence.

Hugh French

Olav Slaymaker

June 2011

Glossary

Part One

Spatial and Temporal Variability of Canada's Cold Environments

Chapter 1

Cold Canada and the Changing Cryosphere

Hugh French¹ and Olav Slaymaker²

¹University of Ottawa

²University of British Columbia, Vancouver

1.1 Introduction

In a series of major reports, first initiated in 1990, the United Nations Intergovernmental Panel on Climate Change (IPCC) has been assessing the nature, impact and implications of current global climate change. The latest report (IPCC, 2007) concluded that warming of the climate system is unequivocal. A global temperature increase of about 0.2 °C per decade is projected for the coming two decades. It has also become clear that the cryospheric components of the climate system are closely linked to this global warming. Moreover, Canada, along with Russia and Greenland, shares the majority of the northern cryosphere.

The general thrust of the 2007 IPCC report, namely, that the Earth's climate is changing with negative consequences, has led to publication of a counter-document by the Nongovernmental International Panel on Climate Change (NIPCC), a non-profit research and educational organization based in the USA. This report (Singer and Idso, 2009) challenges the scientific basis behind the concerns that global warming is either man-made or would have harmful effects. It is argued that twentieth century warming has been moderate and, in fact, is not unprecedented.

We do not wish to enter this global minefield; we leave that to others. Instead, the aim of this book is to simply document the changing nature of Canada's cold environments and, by implication, outline the possible global impacts. We restrict the broader discussion to the northern hemisphere.

1.2 The Cryosphere

The main components of the cryosphere are snow, river and lake ice, sea ice, glaciers and ice caps, ice shelves and ice sheets, and frozen ground (Figure 1.1). Their relevance to climate change lies in: (i) their high surface reflectivity (albedo), (ii) the fact that all three phases of water (solid, liquid and vapour) coexist over the range of the Earth's temperatures and pressures, and (iii) the large amount of latent heat associated with the phase changes between water and ice. It follows that the cryosphere has a strong impact upon the surface energy balance. The presence or absence of snow or ice at the global scale is linked to temperature differences that affect global winds and the thermohaline circulation of the oceans. The latter is initiated by the outpouring of cold arctic waters through Fram Strait in the deep channel between Greenland and the Svalbard archipelago and goes on to circulate throughout the world's oceans.

Figure 1.1 Components of the cryosphere with relevant time scales. Source: IPCC 2007, Figure 4.1., Lemke et al., 2007.

Some cryospheric components invoke positive feedback mechanisms that act to amplify change and variability. For example, a decrease in snow and sea ice extent reduces albedo and increases heat absorption. The resulting temperature increase leads to further reduction in snow and ice extent and consequently accelerated temperature rise. By contrast, other components like glaciers and permafrost act to average out short term variability and may be regarded as sensitive medium term indicators of climate change.

The spatial extent and global volume of the different cryospheric components are summarized in Table 1.1. Collectively, seasonally frozen ground and permafrost have the largest areal extent. As an approximation, the maximum extent of seasonally frozen ground (which includes the active layer over permafrost) is about 51% of the land area of the northern hemisphere. Snowcovers approximately 49% of the northern hemisphere land surface in mid-winter. By contrast, permanent ice in the form of glaciers and ice caps covers less than 1% of the land surface. In terms of global ice volume in the northern hemisphere, the Greenland ice sheet dominates and only a tiny fraction of ice is contained within the ice caps and glaciers of Canada, Alaska, Svalbard, Scandinavia and Russia.

Table 1.1 Area, volume and sea level equivalents of the cryospheric components.

Source: IPCC 2007, Table 4.1., Lemke et al., 2007

1.2.1 Changes in the Cryosphere

The 2007 IPCC report concluded that, since 1980, there has been a global scale decline of snow and ice, and that this decline has continued over the past decade (Figure 1.2). Satellite measurements indicate that the extent of northern hemisphere snowcover has declined by about 2% per decade since 1966 (a figure that is heavily dependent on the starting date chosen) and annual sea ice extent in the Arctic has decreased by 2.7 ± 0.6% per decade since 1978. During the same period, summer sea ice extent has decreased by 7.4 ± 2.4% per decade. There is also evidence that arctic sea ice has thinned by approximately 40% over the 1958–1977 period and in the 1990s. At the same time, field observations from many localities in the northern hemisphere suggest warming of permafrost and a decrease in its spatial extent, an increase in active layer thickness, a decrease in the depth of winter freeze in seasonally frozen areas and a decrease in duration of seasonal river and lake ice.

Figure 1.2 Departures from the long term mean of different cryospheric variables in the Northern Hemisphere since 1960. (a) Polar air temperature north of 65° N, (b) Arctic sea ice extent, (c) Northern Hemisphere frozen ground extent, (d) Northern Hemisphere snow-cover extent, (e) Global glacier mass balance. Source: FAQ 4.1., Lemke et al., 2007.

1.2.2 Ambiguity

These changes in Canada's cryospheric components are discussed in the following chapters. Here, we stress the ambiguity of much of the available data.

To the lay person, possibly the most visible changes that are occurring relate to the worldwide shrinkage of glaciers and ice sheets. Observations of glacier length go far back in time, with written reports from travellers and explorers as early as AD 1600. In Canada, the recent shrinkage of the Athabasca Glacier in the Canadian Rockies (see Figure 15.2) in the last 30 years is highly visible to every tourist who travels the Icefields Highway from Banff to Jasper. When global data from numerous locations in both northern and southern hemispheres are compiled, there is general agreement that glaciers started to seriously retreat after AD 1850. This trend has continued well into the second half of the twentieth century, but with significant local, regional and high-frequency variability. For example, there was a slight slow-down in glacier retreat between 1970 and 1990. However, precipitation-driven growth and advances of glaciers in western Scandinavia and New Zealand occurred during the late 1990s (Chinn et al., 2005).

A different way of looking at the retreat of glaciers and ice sheets is to examine the mass balance at the surface of a glacier (i.e. the gain or loss of snow and ice over the annual hydrological cycle). This is determined largely by climate. Therefore, climate change will affect not only the magnitude of snow accumulation and ablation, but also the length of the mass balance seasons. Unfortunately, records are biased towards logistically and morphologically accessible glaciers. Nevertheless, data from over 300 individual glaciers clearly suggest that glacier wastage in the late twentieth century is essentially a response to post-1970 global warming (Greene, 2005).

Another set of relatively long data records is provided by the freeze-up and break-up dates of river and lake ice. Such dates are of obvious importance to many human activities. In the northern hemisphere, these records extend back 150 years. A recent compilation of such records indicates that 11 out of 15 records show a significant trend towards later freeze-up, while 17 out of 25 records show a significant trend towards earlier break-up (Magnuson et al., 2000). Some of these time series data sets are shown in Figure 1.3. On balance, the average rate of change in dates for both freeze-up and break-up is approximately 5–7 days per century. On the other hand, data from some eastern Canadian rivers over the last 30 years suggest a trend towards earlier freeze-up leading to a significant decrease in open water duration (Zhang et al., 2001). In essence, it is not clear to what extent local observations on lakes and rivers reflect conditions elsewhere in the basin and it is unfortunate that there are no high elevation data included in the analysis. To further illustrate this point, Table 1.2 shows the mean freeze-up and break-up dates on the Mackenzie River, NWT, between 1946 and 1955. Naturally, there is both temporal and spatial variability in the freeze-up and break-up dates over the 1600 km distance from Great Slave Lake to the Arctic Ocean at the Beaufort Sea. This variability reflects not only latitude and climate, but also the influence of tributaries and the large water bodies at either end of the system. Russian arctic river data are equally complex; recent analyses indicate earlier freeze-up of western Russian rivers, but later freeze-up of rivers in eastern Siberia over the last 50–70 years (Smith, 2000).

Figure 1.3 Time series of freeze-up and break-up dates of several northern lakes and rivers. Source: Magnuson, et al., 2000.

Table 1.2 Mean freeze-up and break-up of the Mackenzie River, NWT, Canada, 1946–1955.

Source: Mackay, 1963

The same ambiguity characterizes recent trends in Canadian and global permafrost temperatures, as summarized by both Smith et al. (2005) and the 2007 IPCC Report (Table 1.3). For example, data from the northern Mackenzie Valley, in the continuous permafrost zone, indicate that the temperature of permafrost at 20–30 m depth increased by about 1 °C during the 1990s. However, in the warmer permafrost of the southern Mackenzie Valley there is no significant trend. Elsewhere, in Québec and the High Arctic, observations indicate that a cooling of permafrost in the mid 1980s and mid 1990s has been followed by warming since 1996.

Ambiguity is also present in changes in the extent of sea ice and terrestrial snowcovered areas. While there is a decreasing trend in snowcover in North America's western mountains from 1950 onwards, especially in spring, snowcover area actually increased in the November–January period between 1915 and 2004 due to increases in precipitation. As regards the widely publicized decrease in arctic sea ice, there are several cautionary considerations. First, satellite data are only available from the early1970s, second, it is difficult to distinguish between first year and multi-year ice from passive microwave data and third, the thickness as well as the spatial extent of sea ice must be considered.

In summary, therefore, one must hesitate before concluding that the northern hemisphere cryospheric components unambiguously indicate global climate warming. Clearly, longer time-series are urgently required, in the absence of which, statistical and modeling studies must assume importance.

1.3 Cold Canada

Coldness is a dominant and pervasive characteristic of Canada. Snow and subfreezing temperatures are common and widespread, the only exception being the maritime lowland fringes of British Columbia. On the other hand, the large majority of Canada's population resides in a narrow, 100–150 km wide, belt along its southern border with the United States. Here, climate is largely temperate, seasonal agriculture is possible, plant and animal productivity is relatively high, and the constraints of cold are temporarily forgotten for at least half of the year. But in the rest of the country, in the north, and at higher elevations in the mountains of both eastern and western Canada, the constraints imposed by cold persist throughout the year.

The dimensions of coldness include not only low absolute temperatures, but also exposure to wind chill, snow, ice and permafrost. In addition, the magnitude, duration and frequency of their occurrence must be considered. Frozen lakes, frozen rivers and frozen or ice-infested marine waters also reflect this coldness, while ice sheets and glaciers testify to a Quaternary heritage, in which much of the country was covered by continental ice several kilometres in thickness as recently as 14 500 years ago.

1.3.1 Human Occupancy and Cold Environments

The earliest immigrants into northern Canada must have been sensitive to the cold nature of the country into which they had moved. Whether they were conscious of the continuous change in the various components of the cryosphere is a moot point. But it is generally agreed that the earliest inhabitants must have crossed the land bridge that connected Siberia and Alaska at some time between 40 and 13 ka BP. During the majority of that time much of what is now Canada was covered with massive continental ice sheets and vast melt-water lakes.

By 10 ka BP, the Cordilleran ice sheet had broken into many discrete sections, the Laurentide ice sheet had retreated from the Gulf of St. Lawrence and the first indications of temperate rain forest appeared on the B.C. coast. The so-called Fluted Point people were hunters living close to the receding ice sheets 12–10 ka BP. Clearly, their lives must have been dominated by the cold environments into which they had moved. But by 4 ka BP the Early Nesikep culture of the BC Interior, the Early Northwest Coast culture and the Early Paleo-Eskimo cultures of the High Arctic and northwest Greenland had all emerged, and the environment had become quite similar to that of the present (Wright, 2001). As the ice sheets became more distant, life became progressively more influenced by the successive biomes that made eking out an existence so much more possible. The evidence from archaeology and palynology suggests that environmental change and cultural change went hand-in-hand. Many cultures succeeded in adapting to the changing environment, but others, alas, did not adjust and were eliminated.

Contemporary human activity in Canada, whether it be agriculture, building construction, leisure activities or transportation, to name but a few, is certainly influenced by prevailing climatic conditions. As just one example, Figure 1.4 summarizes the physical and logistical constraints from the viewpoint of oil and gas exploration activity in the High Arctic. One can devise similar schemes for other types of activities in the arctic and subarctic regions, and for mountain environments, be they road/rail/water transportation, mining, skiing or hiking. In all cases, the pattern of physical and logistical constraints associated with Canada's coldness is clear.

Figure 1.4 A typical planning schedule for resource exploitation in northern Canada and the High Arctic islands. Source: French and Slaymaker, 1993.

1.3.2 Wind Chill

People are especially vulnerable to the combination of low temperatures and strong winds. In Canada, it is not uncommon, as in parts of central Keewatin, for air temperatures to fall below –40 °C, with winds in excess of 30 km/h. An extreme situation was recorded at Chesterfield Inlet for the entire month of January, 1935, when mean daily temperature was −43 °C and mean wind speed was 16 km/h. To describe and cope with such conditions, a ‘wind chill’ factor is widely used in Canada and elsewhere in the world. This is based upon the cooling effect of the wind on naked flesh and is expressed in kilocalories per square metre of exposed skin surface per hour. It is generally accepted that wind chill offers a reasonable indication of the degree of discomfort experienced by the human body in a cold climate.

A user-friendly concept of wind chill is to think in terms of equivalence; that is, the temperature of still air that would give the same sensation of cold as the combination of actual air temperature and wind. Figure 1.5 illustrates such a wind chill nomogram devised for use by US Air Force personnel at the Goose Bay Air Base, Labrador, in the early 1960s.

Figure 1.5 The temperature/wind chill index: a nomogram used by US military personnel at Goose Bay Air Base, Labrador, in September 1963. Read the temperature horizontally and the wind velocity vertically. The point of intersection is the wind chill factor. For example, if the wind were 30 km/h and the temperature −25 °C, the wind chill index would be V. Legend: I. Comfortable with normal precautions. II. Work and travel become more uncomfortable unless properly clothed. III. Work and travel become more hazardous unless properly clothed. Heavy outer clothing necessary. IV. Unprotected skin will freeze with direct exposure over prolonged period. Heavy outer clothing becomes mandatory. V. Unprotected skin can freeze within one minute of exposure. Multiple layers of clothing mandatory. Adequate face protection becomes important. Work and travel alone not advisable. VI. Adequate face protection mandatory. Work and travel alone prohibited. Supervisors must control exposure time by careful work scheduling. VII. Personnel become easily fatigued. Buddy system and observation mandatory.