Arguments
Glacier loss is accelerating because of global warming
Posted on 18 April 2018 by John Abraham
With global warming, we can make predictions and then take measurements to test those predictions. One prediction (a pretty obvious one) is that a warmer world will have less snow and ice. In particular, areas that have year-round ice and snow will start to melt.
Alpine glaciers are large bodies of ice that can be formed high in mountains, typically in bowls called cirques. The ice slowly flows downwards, pulled by gravity, and is renewed in their upper regions. A sort of balance can occur where the loss of ice by melting or flowing at the bottom is equal to the gain of snow and ice by precipitation.
As the Earth warms, the melt line moves upwards so that the glacier melts faster and faster at the bottom, shortening the glacier and reducing its mass. Ultimately, the melted water flows into streams and rivers and ends up in the oceans, contributing to accelerating sea level rise.
While glaciers are interesting from an intellectual standpoint, they are also important to ecosystems and society. For example, the rate of glacier melt affects downstream water levels, river flowrates, and the water available for human use. So, it would be really important for us to be able to predict what will happen with glaciers in the future and plan for how water availability will change.
Of the groups that track glaciers, my favorite is the World Glacier Monitoring Service, which publishes a survey of the mass changes from selected glaciers around the world, available here and summarized below. The graph shows changes to the mass of the glaciers that are monitored, measured in millimeters of equivalent water.
Changes to water content of glaciers. Illustration: World Glacier Monitoring Service
But this doesn’t tell the whole story because there is very little information about glacier health in the high latitudes (Northern Alaska, Canada, Northern Europe, Northern Russia, etc.). Very few temperature records exist in high elevations in these regions. Furthermore, the temperatures do not extend back very far in time. So, it is challenging for scientists to develop a long-term perspective on glacier health in these areas.
And this is why a new study attracted my attention. A paper was just published by the American Geophysical Union that shared research carried out by Dominic Winski and his colleagues.
This team of researchers extracted ice cores from the glaciers on Mt. Hunter, in Alaska. The ice cores held snow and ice from as far back as 400 years. The researchers showed that the amount of water melt currently is 60 times greater than it was prior to 1850. They also found that the summertime temperature changes on Mt. Hunter are almost 2°C per century (about 3.5°F). To put this in perspective, the temperatures are rising about twice as fast as global temperatures.
It's projected that 70% of glaciers will be gone from British Columbia by 2100, with about 50% loss in the coast ranges which are wetter and 90% loss in the drier Rockies. Most of the remaining glaciers by that time will be in the North West corner of BC.
Western Canada to lose 70 per cent of glaciers by 2100
In 2015 "The Blob" of warmer water in the Pacific off the west coast of Canada helped create condition that saw a significant increase in the rate of melting of some glaciers.
Glacier melt in B.C. mountains reaches 'shocking' levels
This will be of growing concern to the 2 billion people who are sustained by the waters of glaciers on the Hindu-Kush, Himalayas and mountains of N.W. China
Interesting how the graph of mass balance shows a curved form over the full time period, although it is not exactly smoothly rounded. However its an acceleration, that reinforces the information suggesting sea level rise has accelerated.
The above is an excellent article that expands my knowledge of glaciers in the global climate picture, but there is one critical aspect that I have not seen summarized for lay readers.
It is obvious to anyone with even a basic knowledge of geography and hydrology that China, India, many SE Asia nations as well as South American nations on the western slopes of the Andes depend on glacier melt to feed their rivers and support their civilizations. The number of humans in both the countryside and major cities that depend on the great rivers of SE Asia is staggering. (Conversely, the glaciers of Alaska, Greenland and West Antarctic & the Antarctic Peninsula are important with respect to sea level rise, but not critical as water sources for large populations.
Water and the balance between its solid, liquid and vapor/gas states is the magic that makes the difference between a dead, rocky planet in the proper solar radiation zone, and one that teems with fertile soil and life. Water - supplies, droughts and floods - will likely be a primary factor in causing turmoil, strife and tragedy in modern civilization as AGW/CC progresses.
If anyone knows of a comprehensive summary of human dependence on mountain glaciers - and/or winter snow packs as in California - please post a link. The likely progression of events includes increasing overall glacier-fed river water flow rates for now - in erratic patterns including floods and low flows. In the near future - as mountain glaciers are reduced to fractions of their former size and volume - overall flow rates will "permanently" decrease. This will have dire consequences for the downstream farmers and cities who have depended on glacier-fed rivers for centuries.
(I will search the internet over the next couple of days, and if I find a good summary, will post a link.)
Of course the amount of percipitation is likely to be the same or greater in a glacier free world but the water will flow down the rivers to a large extent in the winter when it is less needed and not in the summer when it is. Countries, where it is possible would be wise to become absolute fanatics about spreading beavers through the head waters of all streams and mounting a wide and deep education program in the media and in the schools about the benefits beavers bring. http://mtkass.blogspot.co.nz/2007/07/canadian-beaver-pest-or-benefactor.html
Useful articles on the glacier issue:
www.ipsnews.net/2011/09/200-million-depend-on-melting-glaciers-for-water/
www.scientificamerican.com/article/shrinking-mountain-glaciers-are-affecting-people-downstream/
news.nationalgeographic.com/news/2011/12/1112-melting-glaciers-mean-double-trouble-for-water-supplies/
From the next to last paragraph in the above article - "And this is why a new study attracted my attention. A paper was just published by the American Geophysical Union that shared research carried out by Dominic Winski and his colleagues."
The mt hunter study is interesting for a number of reasons in that it confirms several things most everyone knows.
agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JD027539
The first point is that two ice cores were drilled down to 208 meters at which point they hit rock. The 400 year point (from 2013 to 1613) was reached at 164.8 meters which left approximately 44 meters which extrapolates to approx 100-300 years for the remaining ice. in other words mt hunter was ice free sometime between 1300-1400 which coincides with the end of the MWP.
Second, this is another of several data points that indicate that the MWP was more wide spread than the convential/current climate science conclusions. This is also consitent with the exposed tree stumps from the mendenhal retreating glacier which was carbon dated circa 1000-1100ad.
Third the study points out the the melting is 60x more than circa 1850 which is to be expected since that is considered the end of the LIA.
In summary, the Mt hunter study adds additional confirmation and insight to what is already known.
Steveh:
Your analysis is not supported by the paper you reference. They specifically state that the thickness of each year of ice becomes thinner as you go down in the ice core. Below 165 meters the layers are too thin to resolve, while near the surface they are as thick as a meter. This means your estimation of 100-300 years previously to be ice free is just something you made up. The actual time to the bottom of the core is much longer, it is not discussed in the paper. The data do not support your claim that this ice core relates to the MWP. I did not see any mention of the MWP in the paper.
In summary: you have made up any statements about the MWP, they are not supported by the data in the paper.
Michael, Steveh should answer for himself, but I think he is echoing WUWT commentators. If the ice core is 400 years old at bedrock, then that "proves" Mt Hunter was ice-free pre-1600 (ie MWP) and only re-glaciated in LIA which are now thankfully "coming out of". I kid you not.
I wish people would actually read papers they cite. That paper is entirely consistent with the established phsyics of AGW.
Scaddnp:
I thought as much. I posted so the absurd claim that Mt. Hunter was ice free were not left unrebutted on the board. The paper states that is was very rare (less than one melt day per decade) for Mt Hunter to have any melt at all in the 1600's. Even if the MWP affected the glacier it would have caused occasional melt, not deglaciation.
>nigelj - thank you for the glacier/water supply links. I shall read them in the near future as well as search for more.
It is difficult to determine which negative effect of AGW/CC will cause the most damage to human civilization over various time periods, but the cumulative impact will ultimately be devastating. It appears that the distribution of changes in large-scale agricultural productivity might favor Russia while the U.S. suffers - an interesting quirk I was not aware of until recently.
At age 76, I am alive to witness the slow acceleration of the negative effects of AGW/CC , but the generation after me will likely to be the first to be seriously threatened.