How Unusual Was 2015 in the 1984–2015 Period of the North Cascade Glacier Annual Mass Balance?

Mauri Pelto

doi:10.3390/w10050543

Abstract

In 1983, the North Cascade Glacier Climate Project (NCGCP) began the annual monitoring of the mass balance on 10 glaciers throughout the range, in order to identify their response to climate change. Annual mass balance (Ba) measurements have continued on seven original glaciers, with an additional two glaciers being added in 1990. The measurements were discontinued on two glaciers that had disappeared and one was that had separated into several sections. This comparatively long record from nine glaciers in one region, using the same methods, offers some useful comparative data in order to place the impact of the regional climate warmth of 2015 in perspective. The mean annual balance of the NCGCP glaciers is reported to the World Glacier Monitoring Service (WGMS), with two glaciers, Columbia and Rainbow Glacier, being reference glaciers. The mean Ba of the NCGCP glaciers from 1984 to 2015, was −0.54 m w.e.a−1 (water equivalent per year), ranging from −0.44 to −0.67 m w.e.a−1 for individual glaciers. In 2015, the mean Ba of nine North Cascade glaciers was −3.10 m w.e., the most negative result in the 32-year record. The correlation coefficient of Ba was above 0.80 between all North Cascade glaciers, indicating that the response was regional and not controlled by local factors. The probability of achieving the observed 2015 Ba of −3.10 is 0.34%.

Highlights

The annual glacier mass balance measurements are the most accurate indicators of short-term glacier response to climate change [1,2]
The World Glacier Monitoring Service (WGMS) [2,3] has recognized that the changes in glacier mass are a key aspect of glacier monitoring, providing important information for assessing climatic changes, water resources, and sea level rise, and they maintain the most extensive data set on global glacier mass balance
The South Cascade Glacier (Figure 1) is monitored by the USGS (United States Geological Survey), and the Columbia Glacier and Rainbow Glacier are monitored by the North Cascade Glacier Climate Project (NCGCP) [3]

Summary

Introduction

The annual glacier mass balance measurements are the most accurate indicators of short-term glacier response to climate change [1,2]. The WGMS has recognized the continuous long term programs with consistent measurement programs as reference glaciers [3], there were 42 present world-wide in 2017. This network has proven valuable, but in many areas the number of glaciers that are monitored are limited [3]. There are three reference glaciers in the conterminous United States, and all are found in the North Cascades. The South Cascade Glacier (Figure 1) is monitored by the USGS (United States Geological Survey), and the Columbia Glacier and Rainbow Glacier are monitored by the North Cascade Glacier Climate Project (NCGCP) [3]

Methods

Results

Discussion

Conclusion