Global Glacier Change Bulletin 3 (WGMS) Reports Increasing Mass Balance Losses

On July 2, 2020April 24, 2024 By mspeltoIn glacier climate change, Glacier Observations

Figure 1. Regionalized mean annual mass balance of WGMS reference glaciers 1980-2018, with 2019 being a mean of reference glaciers.

Glaciers have been studied as sensitive indicators of climate for more than a century and are now experiencing a historically unprecedented decline (Zemp et al, 2015). Glacier fluctuations in terminus position, mass balance and area are recognized as one of the most reliable indicators of climate change. This led to glacier mass balance being recognized during the International Geophysical Year (IGY) in 1957 as a key focus area for developing long term data sets and the need to establish an international data repository.

Today this data reporting system is managed by the World Glacier Monitoring Service (WGMS). WGMS annually collects standardized observations on changes in mass, volume, area and length of glaciers with time, and additionally collecting statistical information on the distribution of glaciers from inventories. WGMS just published their third Global Glacier Change Bulletin, a comprehensive data report covering the 2015/2016 and 2016/2017 hydrologic years. I review some of that information here with updated reference glacier mass balance data from WGMS for 2018 and 2019.

The data set compiled by the World Glacier Monitoring Service has 45,840 measurements on 2540 glaciers (WGMS, 2020). Annual mass balance measurements are the most accurate indicator of short-term glacier response to climate change. WGMS, (2020) data set has 7300 annual balance values reported from 460 glaciers, with 41 reference glaciers having 30+ year consecutive ongoing records. Annual mass balance is the change in mass of a glacier during a year resulting from the difference between net accumulation and net ablation.

The key data set is the annual balance record from the reference glacier network, these glacier have extensive continuous field monitoring programs with at least a 30 year record. For example on Columbia Glacier, Washington I have been in the field 36 consecutive summers, over 120 days taking 4600 measurements with 63 assistants. Figure 1 above illustrates glacier mass balance for the set of global reference glaciers for the time-period 1980-2019. Global values are calculated using a single value (averaged) for each of 19 mountain regions in order to avoid a bias to well observed regions.

In the hydrological year 2016/17, observed glaciers experienced an ice loss of -550 mm, and 2017/18 of -720 mm. For 2018/19 hydrologic year a regionally averaged value will not be available until December 2020, the overall mean of all reference glaciers of -1241 mm, compared to -1183 mm in 2017/2018. This will make 2019 the 32^nd consecutive year with a global alpine mass balance loss and the tenth consecutive year with a mean global mass balance below -700 mm. The simple mean mass balance of WGMS records has a slight negative bias compared to geodetic approaches, but this bias has been effectively eliminated with the regionalized approach now used by WGMS, see Figure 2 (WGMS, 2020).

Figure 2. Glaciological mass balance of all glacier, reference glaciers (mean), regional mean of reference glaciers and regionalized mean geodetic mass balances for the 1930-2017 period. Pay particular note to the 1960-2017 period where the data records are better. Observe the similarity in cumulative mass balance losses regardless of approach.

The decadal averaged annual mass balance was -172 mm in the 1980’s, -460 mm in the 1990’s, –500 mm for 2000’s and – 889 mm for 2010-2019. The increasing rate of glacier mass loss, with eight out of the ten most negative mass balance years recorded after 2010, during a period of retreat indicates alpine glaciers are not approaching equilibrium and retreat will continue to be the dominant terminus response (Pelto, 2019; WGMS, 2020). The accumulation area ratio is an indication of the expansion of the ablation areas globally, despite retreat accumulation areas are shrinking. The decline in accumulation area extent, hence AAR has been rapid, the data in 2017/2018 yields a mean of 13%, whereas the average needed to be in balance is 56%. The low AAR in 2019 is illustrated at two reference glaciers Lemon Creek, Alaska and Alfotbreen, Norway below.

Years	Ba	AAR
1980-1989	-172	47
1990-1999	-460	44
2000-2009	-525	35
2010-2019	-889	28

Table 1 Glaciologic annual balance for each decade from the WGMS reference glacier mean of the 19 regions. The AAR is a simple mean of the reference glaciers.

Landsat images of Lemon Creek Glacier, Alaska and Alfotbreen, Norway in 2019. White dots indicate the glacier boundary on Alfotbreen, purple dots the snowline. Lemon Creek AAR=0% Alfotbreen AAR=~15%

Detailed information is reported for 20 glaciers distributed around the globe that includes annual mass balance maps as illustrated from Columbia Glacier. The relationship between elevatation and annual balance is the balance gradient seen below for Mocho Glacier, Chile. This glacier is in the lake district of Chile at 39.90° S and 72.00° W and did not have significant accumulation in 2016 or 2017. The AAR-annual balance relationship and the ELA-annual balance relationship and annual balance record are reported, as exemplied by Silvretta Glacier, Switzerland, where negative balances occurred in 2016 and 2017.

The result of the rising snowline is mass losses, which drives glacier retreat. This also leads to decreased average albedo and surface lowering, which in turn cause pronounced positive feedbacks for radiative and sensible heat fluxes. This rapid decline in mountain glaciers chronicled by WGMS is expected to accelerate. Huss et al (2017) describe a cascade of effects that are occuring, impacting ecosytems, communites and our economy.

Annual mass balance maps and measurement network on Columbia Glacier.

Annual balance gradient for Mocho Glacier, Chile.

Annual balance record and annual balance relationship to both AAR and ELA on Silvertta Glacier.

Global Glacier Change Bulletin-Many Glaciers Same Story

On December 4, 2017April 28, 2024 By mspeltoIn climate change glacier retreat1 Comment

Cumulative glacier mass balance losses reported by WGMS by region, all glacier, reference glaciers and geodetic mass balance (Sholes Glacier, WA in background). The data set size, location and type changes but the story remains the same, mass loss resulting from global temperature increase.

The World Glacier Monitoring Service has released the second bulletin of Global Glacier Change. The bulletin provides detailed global and regional information on alpine glaciers particularly for 2014 and 2015. There is data reported from 621 glaciers. The glaciers vary in type and location, yet their response is the same retreat and mass balance loss as a result of the global temperature increases. There are currently 41 reference glaciers with at least 30 consecutive years of detailed field measurement of mass balance. Additionally mass balance is typically reported from 60-80 other glaciers. The graph below indicates that the reference glacier network mass balance losses parallels the losses of all glaciers and that of geodetic assessment of mass loss from remapping. The report indicates that alpine glaciers have lost 0.9 m w.e. per year. This continues the unprecedented trend of mass loss that is driving glacier retreat as well. In 2014 and 2015 316 mass balance observations are reported from 166 glaciers. There are 889 terminus change observations reported from 528 glaciers. The results in graph after graph illustrate that glaciers in all regions of the globe are experiencing mass loss and retreat. As the United States representative to the WGMS, helping pull together each strand of data, is a key task. The result unfortunately is a very strong line of data built of all these strands of glaciers losing mass. The report also contains preliminary data from 2016, which was the 37th consecutive year of mass loss as reported in BAMS State of the Climate 2016 (Pelto, 2017). The deadline for posting initial results on mass balance for reference glaciers in 2017 was Dec. 1 2017. Reporting on the US glaciers it is clear that 2017 will be another year of substantial losses in this region.

Annual glacier mass balance reported for each region. The coloration indicates the increase in mass balance loss in each region with global temperature increase.

There is a section of the bulletin on each region including graphs of terminus change and mass balance on selected glaciers. Below are examples from Western North America and Central Europe. For reference glaciers data is submitted that includes maps of the mass balance, and then charts are derived from WGMS illustrating mass balance changes and the relationships between mass balance and the equilibrium line altitude, and between mass balance and the accumulation area ratio.

Glacier Index of Posts

On March 12, 2012 By mspeltoIn Uncategorized2 Comments

Glacier Index List
Below is a list of the individual glacier posts examining our warming climates impact on each glacier. This represents the first 2.7 years of posts, 180 total posts, 166 different glaciers. I have worked directly on 40. The others are prompted by fine research that I had come across, cited in each post or inquiries from readers and other scientists. I then look at additional often more recent imagery to expand on that research. The imagery comes either from MODIS, Landsat, Geoeye or Google Earth.