Global Climate Affects Yukon Landscape.
Author
Natural climate change versus human contributing factors.
Bennefits suit humans, disatorous for nature.
My name is Brent Little and I work here as a park interpreter for Kluane National Park and have been here for many decades. I've gotten to know the park very well and actually have seen change over time in this area. That means a lot when you actually visually see change in the landscape over a period of decades. I wanted to introduce the park to you as I know it from the changes that I have seen in this area over the years and pull back the clock of time several thousand years, even millions of years to give you an idea of change over time.
So climate change is a very small part of the picture. It's important, but it is not the end of the story. To begin with we are at the edge of Kluane National Park, which is a national park and a world heritage site. One of the largest world heritage sites in the world along with Wrangle St. Elias. It encompasses three main features; the highest mountains in Canada. The mountains we see behind us are the Kluane ranges which are a mere two to three thousand meters. The mountains in the ice fields are up to 6000 meters, and covering those 6,000 meters is one of the largest non polar ice fields in the world.
So if we look at a topographic map you get an idea. We're located just north of the town of Haines Junction and the Alsek Valley which is behind us. It is one of the few non-glaciated valleys that comes from the interior all the way to the coast. It is a valley that is seen dramatic change over the years, which I'll try to give you an idea of.
The main feature of this area is post glacial lakes. What we're standing on here is a shoreline of a glacial lake that flooded this valley repeatedly over the last several thousand years. The lake that washed up on the shore has created this beach which we're standing on, about 5,000 years ago. So you can imagine a lake extending from here across to those mountains and 60 kilometers downstream to the little glacier. Huge lake, much larger than today's Kluane Lake, this lake has been formed by the surging Lowell Glacier which every 100 years or so decides to surge. What causes that surge is melt water forming through the ice creating a mill well, creating a subglacial lake which lifts the ice off of the bedrock and the whole thing goes forward 10 to 100 times faster than its normal rate. This has happened in the past; the most recent glacial surge was in 1725 they estimate and created a glacial lake in this valley until 1850. So, many of the Native Elders of this area remember it as a huge Lake and you can still see the shorelines and the driftwood. From the results of that lake and then when it broke, was a very dramatic event.
There was a huge ice dam. We're talking about an ice dam that was maybe a hundred meters and three kilometers across. The ice dam broke and this lake is estimated to have drained in two days would have been stronger than the outflow of the Amazon River when it did so it created a series of glacial lakes further downstream. When it finally came to the Pacific Ocean, which is only a hundred and sixty kilometers away, there's a huge torrent of water and Native Elders from the coastal area said there was a huge disaster there and it washed the village and all the occupants out to the sea. This is also recorded in Native Legend and they have their own interpretation of this as well. Since the time of the draining of that lake, this valley has slowly become treed and populated by different plants and animals and only in the last hundred and fifty years has it been explored by Europeans. We've gone from hiking trail or walking trail, using horse and wagon during the Gold Rush era, to now paved highway going past our door in a very short period of time. But looking at it from a glacial perspective it's taken at least 10,000 years for this landscape to be modified by ice. Going back even further than that, these mountains are not only the highest mountains in Canada, they are the youngest mountains in Canada.
These mountains that we see behind us are soft sedimentary bedrock and so is this rock that I'm holding, which I just picked up while walking up. The hill is a good example of a sedimentary rock. Sedimentary means that it's built layer upon layer from different marine sediments and the bands that you see are caused by the accumulation of these sediments. This rock, that I also picked up in the same location, is completely different. This is a granitic rock and comes from the highest mountains in Canada. The reason why it's so rounded is because it was hauled by glaciers and brought here over a period of thousands of years and in the process became very rounded. This is granitic rock from the ice fields and this is sedimentary rock from the front ranges, so we have mountains in motion.
These mountains are still rising about the same rate of growth as your fingernails. There's three smaller tremors each day and one major earthquake every 10 years. So what we're also standing in, is the shock quake fault that separates the older Yukon Plateau from the younger Saint Elias Mountains; younger being 300 million years. These are young mountains, so that gives you a very quick overview of the highest mountains in Canada, one of the largest non polar ice fields in the world and the climatic overlap of Arctic and Pacific climates.
This river flows into the mountains and south to the Pacific. Just north of us the Kluane Lake, which drains the watershed to the north, goes eventually to the White River and Yukon River and the Bering Sea. So you have the overlap of Pacific climates and Arctic climates here which gives us a lot of biodiversity different types of plants and animals. Here we have the northern limit of Pacific species and just north of us, one hour north of us by car, we have the southern limit of some Arctic species. So it's an incredibly rich area and all of those features have set aside this area as a world heritage site. It's found, not only nowhere else in Canada, but nowhere else in the world, so pretty significant site.
We are now in the boreal forest of Kluane; boreal just being another name for northern forest. The boreal forest is dominated by the white spruce trees, Aspen, Poplar, Balsam, Poplar and further west, the Lodgepole Pine. It's a very rich forest and circles the entire world at the 60th parallel. It crosses all of Northern Canada, Alaska across to Scandinavia, all of Asia and back again so it's a very important forest zone for absorbing carbon dioxide, which is a major greenhouse gas. The only force that is more important for absorbing carbon dioxide is the tropical rainforest. But the Boreal forest is one of the world's last remaining Forest zones that doesn't have major intrusion by people.
When you quickly look at the forest through a glimpse and a short visit, you'll notice there's dead trees and living trees. This is because of the outbreak of the spruce beetle that started in about the mid-1900s. The beetles are always in the forest, but it goes through cycles every 20 years of high points and low points. And the beetle has started its infestation in the 1990s actually, in Alaska and the Kenai Peninsula and then spread its way into the interior. That's because we had both 10 years of very warm winters where we only had 40 below very rarely, in fact, the average temperature was more like 20 below which is not cold enough to kill off the beetle. You need sustained temperatures of minus 30 to minus 40 to kill off the beetle, so we had an increase in the beetle population. They had an explosion in population and they spread through the spruce forest.
This is a good example of change over a relatively short period of time and this tree is a good demonstration of that. This tree is quite old, It's got a large girth. We can estimate the age of this tree to be about 200 years at least and the fungus that is going on the side here is a that may have formed over the last 10 or 20 years. It's at the end of its natural life cycle and has fallen over. It will take another 200 years for this tree to decay and form a layer of soil. Is the tree dead? It's not living, but is not dead. 90 different species of animal life live on what we would call a dead tree. It's the spruce beetle that causes the initial infestation that kills off the tree, then the carpenter ants come in, then the woodpeckers come in, then the parasitic wasps come in. Then the woodpecker makes a nest in the tree. It hollows it out then another bird species moves in and on and on. And on so 90 different species of animal life live in what we call a dead tree.
The median lifespan of trees here is 200 years at this elevation, if they're not killed off by fire or human intervention. That's that's maximum; here to 200 even is pushing. Most trees here would probably only live to be a hundred. At lower elevations it's fairly warm climate but as you get higher, either higher in altitude or higher in latitude the trees are smaller. But a tree like the smaller ones that are maybe so in diameter, are probably over a hundred years old already. This one you could easily say is 200 years old, which is the grandpa of all trees.
Here we are at the viewpoint of the spruce beetle trail and if you look out to my right you'll see from afar the forest appears to be what we would call a sick forest, or a dying forest, but that is not true. It's actually a very healthy forest and the spruce beetle has passed through this area and is now moving on. So the spruce beetle reached the peak in about 2005 and since then, the population of natural predators has increased. We've had a few cold winters and the population of the beetle has crashed. Once again nature has come to an equilibrium.
When we talk about climate change we're looking through too narrow a window. Basically, we're only talking about within our lifetime. There have only been climate records here in the Yukon since the turn of the century to turn of the past century, so maybe 400 years. We've had any accurate idea of climate, but to really get a proper idea of climate and climate trends you need to look through a much longer lens of several hundred years. This forest is a climax spruce forest. The trees are old and weak trees that have been selected by the spruce beetle and are falling down. But there is still a very important part of the forest to return nutrients to the ground and the young tree, like we can see here, has seen no effect of the beetle whatsoever. It's a young strong tree, lots of minerals and nutrients going up the tree and food coming down and the tree is not affected by the beetle. But older weakened trees as everything in nature get selected out and succumb to the beetle. It is another good example of climate change as we would perceive it in our short lifetime.
So that is the north face of what is locally known as Mount Archibald. I'm sure the native people have a much nicer name for it, but it's one of the highest peaks in the front range. It's over 3300 meters and there's more annual buildup of snow than there is annual runoff. Over the terms of thousands of years, small alpine glaciers begin to move down its northern slope. As you can see the glacier forming up past the treeline, more the snow line, and then it feeds down to a small valley glacier. This valley glacier oozes like slow molasses through the rocks and a small piece of it has been exposed right at the base here and to create a quite an attraction for people as an ice cave. It attracted a lot of people into this area, actually hundreds of people. It got to be a bit of a hazard because it's an active landscape moving and it collapses. Now the ice cave is completely collapsed and it's just a good example of change in a recent glacial path. This glacier probably extended much further down the valley 5 or 10 thousand years ago, but over the years, is slowly melting back. The overall thickness of the ice fields is going down by about a meter a year. There's still two kilometers left to go, so it's a slow change through time. You know old mountaineers that were here in the 1930s, they used to be ice climbing up ridges. There's no more ice there. Now climbing on rocks where they used to be climbing on ice.
My personal perspective on it, is that man-made climate change is a small part of a bigger picture. One of the biggest changes in the environment here was in the early 1800s and that was as a result of volcanic action. Yes, we're accelerating climate change, but we're not the sole source of climate change, is my perspective. Environmental awareness is very important and it's great to see the youth of today getting more and more involved with this. In my era there was no such thing as a course on ecology. There was the standard sciences of physics, botany, chemistry, biology, but they didn't look at the interrelationships of things and it's so refreshing to see young people getting more of an appreciation of the environment and wanting to do something about it to improve the situation. For example plastics is a big thing right now and our overuse of one-time plastics. Of course when you burn plastics, it creates carbon dioxide and carbon dioxide is a major contributor to climate change. So it's great to see young people getting involved and wanting to make changes and force government to take more controls on pollution and lowering our impacts on the environment and just appreciating us as part of a much more interconnected environment and not being sort of the masters of all.
So what happens next to this Forest? Again, we have to look at it through a much longer time-lens than just a few years or even a few decades, but over the course of hundreds of years. As we've seen, this forest is a natural forest that will nicely recover but during these stages of infestation many species benefit from this, particularly insect species, which are the main food sources for other plants and animal species. Birds, like pictured here, the grouse, is actually benefiting from it because it creates more of a mixed wood forest. We can see many dead trees, but we can also see all the green trees coming through. From a moose's perspective or herbivore’s perspective, mature spruce forest is not productive; what they want is mixed wood forest with green trees that they can eat and open spaces where they're more visible. It just creates better habitat for any of the herbivores; that would include varying hares, moose, a variety of bird species and they all benefit from the infestation.
There's more to the boreal forest than meets the eye. This patch is only one part of the bigger picture. Even though the boreal forest covers 60% of the Yukon and 35% of Canada we know little about its intricate workings. It's great to see young people getting more involved and getting a better understanding of how the forest works and broaden their perspective how it’s changed through time. It is evolution, and evolution can be a process of decades, hundreds of years, thousands of years, millions of years. It just helps you put your self in perspective on the bigger workings that are beyond our lifetime.
You’ve got two types of bears that live in this area: grizzly bear and black bear, and it's one of the highest percentages of black bears in western Canada. The major reason for that is because most of the habitat has been destroyed and inhabited that they used to range, as far east as Manitoba. But of course we built the railroad in the 1880s and kept on infiltrating and pushing them further back. So this is one of the last remaining untouched areas where the Grizzlies can feel at home with minimal disturbance from man. Habitat wise, it creates both the high alpine, the sub-alpine and the valley floor, all of which are important for the bears’ survival. Grizzly bears den in the sub-alpine or alpine depending on times of the year when there's plentiful food. It moves its way down in the fall when there's berries at this elevation, then moves its way back up for denning.
It's not one of the highest populations of bears in Canada, that that would be along the BC Coast where there's more food and warmer climate and they don't have to ranger far. But here, the bears to get the same amount of food energy cover a much wider area. There's about one bear every 20 square kilometers of habitat here. So in our little walkabout we've seen these sign posts where the grizzly bears have chewed against the sign and rubbed against it. That's the bear’s way of identifying “this is my territory and I'm identifying my signpost here. I'm leaving my scratch marks. I'm leaving my bear hair here. I might be urinating around here to tell other bears that wait a minute this land’s already taken over by the bears.” So it's nice to be in an area where humankind is not the dominant species. Definitely this is still bear country. We’re the visitors and they’re the permanent inhabitants. So it's nice to be in the country were not the dominant species where bears are the ones that really call the shots and we're just daytime visitors. Another good example of recent change to the environment is caused by the Kaskawulsh Glacier, which is a very large valley glacier just to the north of us. It feeds two river systems: the Kaskawulsh River that goes south to the Pacific and the old name for the Slim's river which goes to the Kluane Lake and eventually the Yukon River and the Bering Sea. This glacier has definitely melted back in a number of years and now has changed its course so that most of the water is pirated by the Kaskawulsh going south to the Pacific and now very little water goes towards Kluane Lake.
It's to the point now, where the Slims Delta is almost doubling in size every 10 years. What used to be islands in the lake, you can now walk to as bare ground. It’s had a dramatic effect on the wildlife because it's creating more habitat. So this fine dust that's in the air is called loess or we would just called air deposited sand and it's very rich in minerals. It's drawing the sheep off the mountain to the river delta, which of course attracts the predators. So no longer do the some of the predators have to climb mountains to get sheep. They can find them very easily on the river flats.
The river flats also have very rich soil. A lot of the plants that the bears depend on, such as wild sweet pea and local lidatropsoroisis are growing in the river delta. That creates more habitat and more food and more bears. So the Slim's River Valley also has one of the highest concentrations of grizzly bears. In the park, it's popular hiking over to the Kaskawulsh Glacier and it creates management problems. So that's just a short-term example of changes just happened in the last number of years. I think the lake has dropped about three meters in two years so the boat docks now are up high and dry. They're nowhere near the water's edge and that has a dramatic effect on the recreational sport fishing because people can't get their boats in the water and it's going to continue. And the Kaskawulsh could continue to capture more and more of the runoff and other than tributaries coming into the Slim's River Valley, it could completely dry up. Kluane Lake could disappear; not in our lifetime, but maybe in our grandchildren's lifetime. And all the river would be going south to the Pacific, not North to the Arctic. It would create more wildlife habitat and it would be a devastating
effect for the communities along the north Alaska Highway. They would no longer have it as a freshwater source, but in the long term the terms, of hundreds of years, it would create more wildlife habitat. Even today if you drive to the north end of Kluane Lake you can see drowned tree stumps from where the lake level had risen in the ancient past and drowned the tree stumps there. So it's pretty dynamic. You’ve got two river systems changing over the course of our lifetime.