[MUSIC] Over the past 11 lessons, we've explored mountains in all of their dimensions. Mountains are complex and fragile ecosystems, characterized by unique biodiversity. They're defined by their steep topography, localized weather systems, and strong climatic gradients. They're the water towers of the world. Providing fresh water to at least half the world's people for domestic use, irrigation, industry, and hydropower. Mountains are also high-risk environments, where avalanches, landslides, volcanic eruptions, earthquakes and glacial lake outburst floods threaten life in mountain regions and surrounding areas. Fragile soils and vegetation cover make mountain areas vulnerable to environmental degradation. Mountains are also places that inspire imagination, and are revered the world over. Mountains are also places experiencing unprecedented change in the face of a warming climate. [MUSIC] >> In this final lesson, we're going to look forward and consider some possible future scenarios for mountain places, people's environments, and economies. To do this, we're going to look back at some of the key points discussed in previous lessons. We'll consider what we know, and what we don't know about the future of mountains. >> Let's begin by discussing the warming climate in which we live. Climate change refers to any significant change in the measures of climate lasting for an extended period of time. In other words, climate change includes changes in temperature, precipitation, or wind patterns, among other effects that occurs over several decades or longer. The physical properties of gasses in the atmosphere allows us to accurately calculate the amount of energy that CO2 absorbs and emits. A doubling of atmospheric CO2 concentration from pre-industrial levels of 280 parts per million, up to about 560 parts per million, would be sufficient to cause average global temperatures to increase between one to two and a half degrees Celsius, and even more over the longer term. Current atmospheric concentrations of CO2 in the atmosphere are now over 400 parts per million. The challenge in determining the exact relationship between a given carbon dioxide level and a specific temperature is that the overall climate system is more complex. Other factors influence temperature, too, including atmospheric dust and volcanic eruptions. The area of forests and grasslands and variation in solar radiation. Warming leads to further feedback effects that either amplify or diminish the initial warming. The most important feedbacks involve various forms of water. As you know already, a warmer atmosphere generally contains more water vapor. Water vapor is a potent greenhouse gas, but it has a very short lifetime in the atmosphere. Consequently, it keeps the increase mostly in step with warming. Thus, water vapor is treated as an amplifier, and not as a driver of climate change. The relative influence of other feedback processes is less certain, but much longer lasting. For example, another important feedback concerns changes in clouds. Warming and increases in water vapor may cause cloud cover to increase or decrease. Which can either amplify or dampen temperature change, depending on the extent, altitude, and properties of clouds. The latest evidence suggests that changes in clouds at a global scale are likely to amplify warming. The average temperatures, rainfall, and their extremes are also strongly effected by local patterns of winds. Surface temperatures and precipitation in most regions will vary greatly from the global average, because of geographical location, in particular latitude and continental position. As well, the ocean is a huge heat reservoir, and tends to moderate climate change. Recent observations of warming of both surface and deep ocean waters, will contribute to amplification of climate change in coming decades. Over the past century, human activities have released large amounts of carbon dioxide and other greenhouse gases into the atmosphere. The majority of greenhouse gases come from burning fossil fuels to produce energy. However, other human activities, such as deforestation, industrial processes, and some agricultural practices, also emit gases into the atmosphere. Greenhouse gasses act like a blanket around the Earth, trapping energy in the atmosphere, and causing it to warm. This phenomena is called the greenhouse effect. And it's natural and necessary to support life on Earth. However, the buildup of greenhouse gases will change Earth's climate, endangering human health and welfare and both natural and managed ecosystems. The United Nations Intergovernmental Panel on Climate Change, also known as the IPCC, is the leading international advisory body comprised of over 800 leading scientists. They released their fifth assessment report in March 2014, concluding that scientific evidence that warming of the climate system is unequivocal. Our lives are connected to the climate. Human societies have adapted to the relatively stable climate we've enjoyed since the last Ice Age, which ended several thousand years ago. A warming climate will bring changes that can affect water supplies, agriculture, power and transportation systems, the natural environment, and even our own health and safety. There's no debate about the reality that humans are altering the Earth's climate. Every major scientific agency representing every country in the world, that's over 200 organizations, all agree that human made climate change is real, and that it's happening now. To curb the change will take global participation and co-operation. The 21st United Nations Climate Change Conference was held in Paris, France in December 2015. The conference negotiated the Paris Agreement, a global agreement on the reduction of climate change, the text of which represented a consensus of the representatives of 196 countries. The agreement calls for zero net anthropogenic greenhouse gas emissions to be reached during the second half of the 21st century. In the adopted version of the Paris Agreement, the parties will also pursue efforts to limit the temperature increase to 1.5 degrees Celsius. This 1.5 degree Celsius goal will require achieving zero emissions by 2050. [SOUND] There is growing evidence that the rate of warm is amplified with elevation. High mountain environments experience more rapid changes in temperature than environments at lower elevations. Elevation-dependent warming can accelerate the rate of change in mountain ecosystems, cryospheric systems, hydrological regimes, and biodiversity. Mechanisms that contribute to elevation dependent warming include snow albedo and surface based feedbacks, water vapor changes, and latent heat release, surface heat loss, and temperature change, and aerosols. All of these processes lead to enhanced warming with elevation. And it's believed that combinations of these mechanisms may account for contrasting regional patterns. For the highest peaks in Australia, the predicted changes in climate include a decrease in the duration of snow cover, and an even more dramatic reduction in maximum snow depth from over two meters to under 50 centimeters. In this scenario, a 2.9 degree Celsius temperature increase is the equivalent of a 377 meter upward shift in snow-line. Therefore, under the worst case scenario, in less than 50 years, conditions equivalent to the current treeline. Which is at about 1,850 meters in the Snowy Mountains, would be found a meter above the top of continental Australia's highest mountain, Mount Kosciusko. Many scientists believe that the changes occurring in mountain ecosystems may provide an early glimpse of what could come to pass in lowland environments. As the world heats up, mountain glaciers are melting at unprecedented rates, while rare plants and animals struggle to survive over ever diminishing areas. And mountain peoples, already among the world's poorest citizens, face even greater hardships. Changes in the volume of mountain glaciers, and in there seasonal melting patterns, have an impact on water resources in many parts of the world. Changes in water availability, due to climate change, are taking place at a time when pressure on water resources for irrigation and food production, industrialization, and urbanization are increasing. Understanding how climate change affects mountains is vital, as governments and international organizations develop strategies to reverse current global warming trends. In addition, local community empowerment can be an essential step towards building climate change resilience in mountain regions. >> You'll remember back to our lesson on glaciers. Ordinarily, if you make climate a little bit warmer, glaciers will shrink a little bit. If the climate is a little bit colder, then glaciers will grow a little bit. And these two things oscillate to establish a balance or an equilibrium. If things get too warm, glaciers won't respond just a little bit. Instead, the volume drops by a large amount. Equilibrium is lost, and you cross a tipping point. It's then irreversible. It just keeps going. Glaciers matter. They give us tangible, visible evidence of the immediacy of climate change. You can think of them as the leading indicator of climate change in mountains. Glaciers are where you can see climate change happening before your eyes. Mike Demuth is an glaciologist with a Geological Survey of Canada, and he's been keeping a close eye on the glaciers of the Rockies for over 30 years. Glaciers like this one, The Peyto Glacier in Banff National Park. Let's have a listen. >> The Peyto Glacier in the Canadian Rockies has, since I first started studying it, has changed dramatically. It's a shadow of its former self. In fact, it's hardly recognizable as a glacier today. When I first started working there, it was approximately 12 square kilometers of ice in the northern extent of the Wapta Icefield. And it's now dwindled to some seven square kilometers, and has lost about 200 meters of thickness, and about a kilometer of length. And super dramatic, my earliest measurements compared to the measurements we're taking now and reporting to the World Glacier Monitoring Service, show that this is part of a pattern for mountain glaciers all around the world. These really accelerated changes in their length, in their thickness, and their mass. >> One of the things you sometimes hear in the debate about climate change is that there are glaciers around the world that are presently getting bigger and advancing. So, how could that be? How could that be a response to a global warming signal? What glaciologists have learned in the Yukon Territory in Canada, where they looked at change in glacial area from 1958 to 2008, is that of the 1,400 glaciers surveyed in 1958, four have gotten bigger after 50 years. Over 300 have disappeared completely. And almost all the rest have gotten smaller. Yes, there's a component of natural variability in the climate change, they observed, but it's not enough to explain the full signal. The warming of the Earth's climate system caused by increasing greenhouse gasses accounts for the rapid change that's being observed here, and in mountains around the world. Glaciers are excellent indicators of change in other ways, too. In fact, the history of ancient climate is embedded in ice, quite literally. Glaciers preserve climate records very much like tree rings, for example. Recall how glaciers are formed. Snow is added over top, and over time, it's compressed and turned into ice. An ice core scientist can then drill holes and pull out a core and examine what's there. And what's there can actually tell us quite a lot. Glaciologist Marin Sharp has been working hard over the past two years to archive Canada's ice core collection, which will soon be housed at the University of Alberta, and become an accessible scientific resource for generations to come. Here's Martin Sharp on ice core research. [MUSIC] >> Ice cores are, if you look at the situation globally, one of the best repositories of information about past climates and past environments. And they certainly give records of much higher resolution than deep sea sediments, for instance, which is the other place that people usually go for these kinds of records. So, there's a lot to be learned from those records. The other thing is that because of climate warming, those records are being eroded, and they're disappearing. There is a collection there that's been assembled over 40 odd years. That was a risk that it was just going to get thrown out into a parking lot and melted. And we wanted to make sure that didn't happen, because the techniques that are available for analyzing ice cores, and the range of information that can be extracted from them now are radically different from what existed at the time when the cores were collected. And we also want to develop the capability to create new cores to look at the new generation of problems. >> By looking at the chemistry of the ice, we can learn about past temperatures. And by looking at the trapped air, we can actually measure past carbon dioxide concentrations. One of the things that ice core scientists have learned is that past temperatures and carbon dioxides vary together. They go up together, and they go down together, and over the past 800,000 years or so, atmospheric carbon dioxide was never higher than about 280 parts per million, until the industrial revolution, when we started adding carbon dioxide to the atmosphere. Today, we're in about 400 parts per million, that's 40% higher than it was when carbon dioxide was varying for only natural reasons. Unfortunately, it appears that we're now heading for 500 parts per million or more. That pace of change we've learned from the ice is 100 to 1,000 times greater than the pace at which things have changed by themselves naturally. The change may seem slight. It's translated today to an increase of only 0.8 degrees Celsius since the mid 1850s. But even that slight change, a rate of change that is projected to accelerate this century, is already having extraordinary consequences. [MUSIC] Rising global temperatures are accompanied by changes in weather and climate. However, the differences between weather and climate is a measure of time. Weather is what the conditions what the atmosphere are over a short period of time, and climate is how the atmosphere behaves over a relatively long period of time. Simply put, even though we may have an extremely cold day, or even a cold winter season for that matter. This doesn't mean that the planet as a whole is not significantly warming over an extended period of time. So, what does that mean for us now? Many places are seeing changes in the rainfall, resulting in more floods and droughts, or intense rain, as well as more frequent and severe heat waves. As these and other changes become more pronounced in the coming decades, they'll increasingly present challenges to our society and to our environment. Here to elaborate on what that means for mountains is geologist Dr. John Clague, professor in the Department of Earth Sciences at Simon Fraser University. >> Mountains are very sensitive to climate change. There are typically glacier ice, a lot of snow and a lot of ice. And over time, over period of years and decades that snow and ice is diminishing. So, it is setting up some conditions that are quite hazardous. We're seeing that lakes that have been dammed by glaciers, or by moraines are beginning to burst. The lakes are emptying out from their dams, and causing severe down-stream flooding. We're seeing more landslides in mountains, because as it warms up, the permafrost that exists in the rock slopes is thawing, and we're getting collapses of mountains. We have one thing going for us in our mountains, our high mountains are not inhabited like, for example, the Andes or the Alps or the Himalayas, where the same processes are operating, and are causing quite a lot of damage and injury as well. But as we increasingly move into our higher alpine zone, we can expect these same problems, all induced by climate change. >> This is the new reality now facing the insurance industries in the industrialized world and elsewhere. The rising probability of catastrophic events is forcing insurance companies to adjust their financial models as they take on more risk. Of course, the reality is that for most mountain people, particularly the disadvantaged and marginalized groups, insurance isn't even an option. Catastrophic hazards in mountains have always hit the more vulnerable isolated mountain populations harder than anyone else. The increasing frequency and severity of non-seismic catastrophic events in the mountains will only exacerbate the poverty in many of the world's mountain areas. The consequences for the billions of people downstream of major mountain areas, who depend on critical environmental resources provided by mountains, like water and biodiversity, hydrological processes will be equally severe.
