Something awesome happened last week. Awesome in the true definition of the word – both ‘awe inspiring’ and ‘something that causes feelings of respect and fear’. The Slims River has stopped flowing into Kluane Lake. The Slims River is pictured on the top left showing it's massive sediment plume flowing into Kluane Lake. For scale, the lake is about five miles across at this section. This event is awesome because it marks the beginning of a climate induced change that will have an immense landscape and water resource effect. Awesome, because it is unclear how and under what time scale changes associated with the loss of this major water source will occur. Awesome because climate change can and will cause major shifts in the landscape and water resources that we have come to depend on.
Kluane Lake is the largest lake in the Yukon Territory, covering 408 km2. From the Little Ice Age to just last weekthe majority of Kluane’s water supply came from the Slims River, which drains the Kaskawulsh Glacier. It has long been hypothesized that with climate change, the glacier will recede to a point where all meltwater is captured by the steeper gradient of the Kaskawulsh River, routing the water south and away from the lake. Though we anticipated this event, somehow it is still surprising that it has occurred. What this means for the lake is uncertain. What we do know is that the seasonal fluctuations in Kaskawulsh melt cause the lake to fluctuate between 1-2 meters through the year. A water level gauge on the lake indicates that the lake level has been falling steadily over the last 60 years, with a total average lowering of just over half a meter. Looking further back in time, we know that the lake spent much of the last 5000 years somewhere between 20 and 27 meters below present level (See infographic below). Increases in Kluane Lake level occurred around 1400 Cal. Yr. BP, when the Duke River began to flow into the lake, and again around 300 years ago, when the Slims began to flow into the Lake. Both rivers are glacially sourced. The Duke River left the party a while back, and will not likely return in the near future (without human intervention).
How will these changes affect lake level in the coming year? decade? How will this change affect lake water chemistry? How will this impact the ecosystem that has come to depend on this freshwater source? I hope someone gives me money to find out.