Dr. Sean Fleming, University of British Columbia
Interview with Sean W. Fleming, PhD, PPhys, ACM, Hydrologic Modeller, BC Hydro,
Adjunct Professor, University of British Columbia. July, 2008.
CA-CP: What is the focus of your research?
Dr. Fleming: My research and applications work has considered, among other things, how the presence of glaciers in a watershed affects the way that river flows respond to climatic variability and change.
“Climatic variability” includes naturally organized patterns in the large-scale circulation of the atmosphere and oceans. The best-known example would be El Niño-Southern Oscillation. This is a sometimes quite severe but relatively short-term type of climatic variation, reflecting individual El Niño or La Niña events for example, which typically last for maybe a year. Although its source area lies nominally in the tropical Pacific Ocean, it affects everything from landslides in California, to fisheries production in the Pacific Northwest, to hurricane activity in the Atlantic, to water resource availability over considerable portions of the planet. Even impacts to stock market performance have been suggested – though if that’s true, such effects may have a lot to do simply with people’s subjective perceptions of how an anticipated El Niño event might conceivably affect the economy!
“Climate change,” on the other hand, involves long-term drift in the climate system, such as an overall tendency toward warmer temperatures. These more persistent changes may arise from a variety of factors, ranging from planetary orbital variations, to complex fractal or chaotic dynamics in the climate system, to human modification of global climate through deforestation and fossil fuel combustion (both of which are of course related to human population growth).
By careful analysis of historical data records, my colleagues and I have found that whether a glacier is or isn’t present in a catchment’s headwaters can make a huge practical difference in terms of the downstream water resource impacts of climatic variability and change. As always, though, there’s some fine print: although the laws of nature don’t vary from one watershed or climatic region to the next, the particular ways in which they are locally expressed do. That translates into considerable remaining uncertainty as to how glaciers modify a given river’s response to climatic variability and change. There is still a great deal to be learned.
CA-CP: How does glacial melt affect different societies, species, and ecosystems? Why should people living in the United States or Europe be mindful of what is occurring with glaciers and climate change?
Dr. Fleming: Melting of mountain glaciers affects societies in a variety of ways. Some are direct and tangible. For others, the lines linking cause and ultimate effect are more circuitous, though the end result may be no less important. I’ll give two examples.
Glaciers are a key source of freshwater – for drinking water supplies, to support agricultural and industrial production, and to drive hydroelectric power generation. One might be tempted to think of glaciers as being a trademark of the frozen north, but altitude can serve as a substitute for latitude: glacial water supplies play an important role through mountainous regions in much of western North America, central Europe, parts of South America, and of course the Himalayas – where glaciers serve as a water source for the world’s two most populous nations, India and China. So the implications of climate-driven glacier changes are very far from being strictly academic, particularly if one considers the wider social and economic implications of changes in water supply availability, and in regions where water supplies are already limited due to either quantity or quality issues.
There are also likely to be ecological implications. Unfortunately, the relationships between the cryosphere, freshwater ecosystems, and climatic variability and change are far from well-understood. We’re talking about multi-faceted interactions between a number of systems, each of which is in turn complex and nonlinear. But the working hypothesis – and it’s a reasonable one – is that the gradual recession, and in some cases eventual disappearance, of mountain glaciers may have far-reaching ecological impacts. Take salmon along the Pacific coast of North America, for example. There is evidence that the relatively strong late-summer baseflows supported by glacial melt may be strongly beneficial for salmon, especially during spawning. Salmon here are a key ecosystem component. They are a food source for other forms of aquatic life, as well as for eagles, bears, and wolves; and they even help sustain the rich rainforests through which the region’s rivers flow, as the spawned-out carcasses serve as a natural source of plant nutrients. Further, strong salmon runs are crucial to traditional First Nations fisheries, to the lucrative recreational angling and tourism industries, and of course to the commercial salmon fishery – as well as all the other economic sectors which indirectly benefit from such activity, ranging from boat sales to local restaurants. Again, the implications of coupled climate and glacier change may be profound and of importance to everyone.
CA-CP: What is Arctic Oscillation and how does your research relate to it?
Dr. Fleming: The Arctic Oscillation is a type of atmospheric circulation pattern – an organized, though not entirely predictable, way in which the climate varies. There are several such patterns; probably the best-known is El Niño-Southern Oscillation. The Arctic Oscillation is a northern-hemisphere effect, though there is a southern-hemisphere counterpart called (logically enough) the Antarctic Oscillation. It was only discovered in the 1990s, although yet another pattern, called the North Atlantic Oscillation, appears to be closely related to it and was identified much earlier.
Perhaps because it’s a newer discovery, less is known about the effects of the Arctic Oscillation relative to many other climatic variability patterns, such as El Niño or La Niña events. My colleagues and I sought to identify whether – and if so, how – the climate, glaciers, and rivers in the southwest portion of Canada’s Yukon Territory respond to the Arctic Oscillation. This is a highly remote subarctic area, but a scientifically important one. Its remoteness has helped the region largely escape development, and it remains very ecologically rich. It also hosts the St. Elias Icefield, which is the largest ice mass outside Greenland and Antarctica, and which helps make it a great natural observatory for studying mountain glaciers and glacier change. And for such a remote and pristine region (data tend to be collected where people live!), there was a reasonable amount of historical meteorological and streamflow records to work with.
In a nutshell, the end result was what we called “selective teleconnectivity”: the water resource productivity of glacier-fed rivers in the region was coupled to the Arctic Oscillation, whereas in snowmelt-fed rivers devoid of glacial ice, only the timing of the seasonal melt freshet showed a relationship. Again, there’s much still to be learned, but it appears this result has to do with the way the Arctic Oscillation apparently modifies spring temperatures in that region, and how this effect may in turn interact with the presence or absence of a glacier within the watershed, which – put simply – amounts to a gigantic ice cube potentially available for melt production.
View Dr. Fleming's faculty homepage
Adjunct Professor, University of British Columbia. July, 2008.
CA-CP: What is the focus of your research?
Dr. Fleming: My research and applications work has considered, among other things, how the presence of glaciers in a watershed affects the way that river flows respond to climatic variability and change.
“Climatic variability” includes naturally organized patterns in the large-scale circulation of the atmosphere and oceans. The best-known example would be El Niño-Southern Oscillation. This is a sometimes quite severe but relatively short-term type of climatic variation, reflecting individual El Niño or La Niña events for example, which typically last for maybe a year. Although its source area lies nominally in the tropical Pacific Ocean, it affects everything from landslides in California, to fisheries production in the Pacific Northwest, to hurricane activity in the Atlantic, to water resource availability over considerable portions of the planet. Even impacts to stock market performance have been suggested – though if that’s true, such effects may have a lot to do simply with people’s subjective perceptions of how an anticipated El Niño event might conceivably affect the economy!
“Climate change,” on the other hand, involves long-term drift in the climate system, such as an overall tendency toward warmer temperatures. These more persistent changes may arise from a variety of factors, ranging from planetary orbital variations, to complex fractal or chaotic dynamics in the climate system, to human modification of global climate through deforestation and fossil fuel combustion (both of which are of course related to human population growth).
By careful analysis of historical data records, my colleagues and I have found that whether a glacier is or isn’t present in a catchment’s headwaters can make a huge practical difference in terms of the downstream water resource impacts of climatic variability and change. As always, though, there’s some fine print: although the laws of nature don’t vary from one watershed or climatic region to the next, the particular ways in which they are locally expressed do. That translates into considerable remaining uncertainty as to how glaciers modify a given river’s response to climatic variability and change. There is still a great deal to be learned.
CA-CP: How does glacial melt affect different societies, species, and ecosystems? Why should people living in the United States or Europe be mindful of what is occurring with glaciers and climate change?
Dr. Fleming: Melting of mountain glaciers affects societies in a variety of ways. Some are direct and tangible. For others, the lines linking cause and ultimate effect are more circuitous, though the end result may be no less important. I’ll give two examples.
Glaciers are a key source of freshwater – for drinking water supplies, to support agricultural and industrial production, and to drive hydroelectric power generation. One might be tempted to think of glaciers as being a trademark of the frozen north, but altitude can serve as a substitute for latitude: glacial water supplies play an important role through mountainous regions in much of western North America, central Europe, parts of South America, and of course the Himalayas – where glaciers serve as a water source for the world’s two most populous nations, India and China. So the implications of climate-driven glacier changes are very far from being strictly academic, particularly if one considers the wider social and economic implications of changes in water supply availability, and in regions where water supplies are already limited due to either quantity or quality issues.
There are also likely to be ecological implications. Unfortunately, the relationships between the cryosphere, freshwater ecosystems, and climatic variability and change are far from well-understood. We’re talking about multi-faceted interactions between a number of systems, each of which is in turn complex and nonlinear. But the working hypothesis – and it’s a reasonable one – is that the gradual recession, and in some cases eventual disappearance, of mountain glaciers may have far-reaching ecological impacts. Take salmon along the Pacific coast of North America, for example. There is evidence that the relatively strong late-summer baseflows supported by glacial melt may be strongly beneficial for salmon, especially during spawning. Salmon here are a key ecosystem component. They are a food source for other forms of aquatic life, as well as for eagles, bears, and wolves; and they even help sustain the rich rainforests through which the region’s rivers flow, as the spawned-out carcasses serve as a natural source of plant nutrients. Further, strong salmon runs are crucial to traditional First Nations fisheries, to the lucrative recreational angling and tourism industries, and of course to the commercial salmon fishery – as well as all the other economic sectors which indirectly benefit from such activity, ranging from boat sales to local restaurants. Again, the implications of coupled climate and glacier change may be profound and of importance to everyone.
CA-CP: What is Arctic Oscillation and how does your research relate to it?
Dr. Fleming: The Arctic Oscillation is a type of atmospheric circulation pattern – an organized, though not entirely predictable, way in which the climate varies. There are several such patterns; probably the best-known is El Niño-Southern Oscillation. The Arctic Oscillation is a northern-hemisphere effect, though there is a southern-hemisphere counterpart called (logically enough) the Antarctic Oscillation. It was only discovered in the 1990s, although yet another pattern, called the North Atlantic Oscillation, appears to be closely related to it and was identified much earlier.
Perhaps because it’s a newer discovery, less is known about the effects of the Arctic Oscillation relative to many other climatic variability patterns, such as El Niño or La Niña events. My colleagues and I sought to identify whether – and if so, how – the climate, glaciers, and rivers in the southwest portion of Canada’s Yukon Territory respond to the Arctic Oscillation. This is a highly remote subarctic area, but a scientifically important one. Its remoteness has helped the region largely escape development, and it remains very ecologically rich. It also hosts the St. Elias Icefield, which is the largest ice mass outside Greenland and Antarctica, and which helps make it a great natural observatory for studying mountain glaciers and glacier change. And for such a remote and pristine region (data tend to be collected where people live!), there was a reasonable amount of historical meteorological and streamflow records to work with.
In a nutshell, the end result was what we called “selective teleconnectivity”: the water resource productivity of glacier-fed rivers in the region was coupled to the Arctic Oscillation, whereas in snowmelt-fed rivers devoid of glacial ice, only the timing of the seasonal melt freshet showed a relationship. Again, there’s much still to be learned, but it appears this result has to do with the way the Arctic Oscillation apparently modifies spring temperatures in that region, and how this effect may in turn interact with the presence or absence of a glacier within the watershed, which – put simply – amounts to a gigantic ice cube potentially available for melt production.
View Dr. Fleming's faculty homepage