In late August 2016, (click here) a deep rift widened and an iceberg heaved away from the Porcupine Glacier in northern British Columbia. Glaciologist Mauri Pelto, who has been analyzing satellite imagery of glaciers since the 1980s, called it “the biggest calving event in North America” that he has ever seen....
August 25, 2015
It may not be obvious to everyone, but, the glacier has a pattern of ice movement. This new calving drastically alters the terminus of the glacier.
To most this simply looks like a big piece of ice no longer exists on the glacier, but, it is more than that. It is a change in the "mass balance" of the entire glacier. The ice flows from the higher altitudes will start to descend more quickly and the glacier will become unstable. These changes are not simply lost ice, it is a change in the entire glacier.
Porcupine Glacier (click here) is a 20 km long outlet glacier of an icefield in the Hoodoo Mountains of Northern British Columbia. Bolch et al (2010) noted a reduction of 0.3% per year in glacier area in the Northern Coast Mountains of British Columbia from 1985 to 2005.Scheifer et al (2007) noted an annual thinning rate of 0.8 meters/year from 1985-1999. Here we examine the retreat of Porcupine Glacier and the expansion of the lake it ends in from 1988-2011 using four Landsat images from 1988, 1999, 2010 and 2011. Below is a Google Earth view of the glacier with arrows indicating the flow paths of the Porcupine Glacier. The second images is a map of the region from 1980 indicates a small marginal lake at the terminus....
The glaciers are water resources. It really is a very big deal.
...Glaciers (click here)
The hydrology of much of the southwestern Yukon is tied to glaciers, which influence both streamflow and water quality. Changes to glaciers due to general climate change could have a profound influence on the hydrology of Yukon’s glacier-dominated basins. In 50 years, between 1958 and 2008, the total ice area in Yukon shrank by 22%. Precisely what this kind of change means for Yukon’s freshwater resources remains unclear. As glaciers recede, streamflow will decrease, but the decrease might not happen right away. At first, increased glacial meltwaters will likely contribute greater flows downstream. If some basins lose their glaciers altogether, the result is likely to be a dramatic shift in streamflow patterns. Glacial melt can also lead to short-term, catastrophic effects, such as the formation of unstable glacial lakes and outburst floods....
