by Judith Curry
The loss of glaciers from Glacier National Park is one of the clearest manifestations of climate change in the United States Signs have been posted throughout the park, declaring that the glaciers will disappear by 2020. In 2017, the Park began removing these signs. What happened, other than the obvious fact that the glaciers haven’t disappeared by 2020?
Not only are glaciers in Montana an important symbol of global warming (e.g. Al Gore’s Inconvenient Truth), glaciers are also an important political symbol for politicians progress in Montana. Earlier this week, Reilly Neill, a (kind of) politician in Montana, followed me on Twitter:
Some sort of progressive academic is leaving twitter taken over by Elon Musk. What??? And miss all this fun???
Well, it’s just a coincidence that I have some analysis of Montana glaciers and climates in my archives; maybe I can help Reilly (and the “real scientists of Montana”) understand what’s going on.
Variation of Glaciers in Glacier . National Park
According to the United States Geological Survey, the total area of Glacier National Park covered by glaciers decreased by 70% from the years 5050 to 2015. The melting process began at the end of the Little Ice Age ( circa 1850) when scientists believe there were 146 glaciers covering the area, as opposed to 26 in 2019.
The first surveys of glaciers in Glacier National Park began in the 1880s, largely focusing on the two largest glaciers – Grinnell and Sperry. A 2017 publication released by the United States Geological Survey titled State of Glaciers in Glacier National Park [link] includes a table of the area sizes of named glaciers in Glacier National Park since the Little Ice Age (LIA) with markers at LIA, 1966, 1998, 2005 and 2015. Analysis of the This data shows:
- ~50% loss from LIA to 1966 (~115 years), average loss ~4.5% per decade.
- Another ~12% loss from 1966-98 (32 years), an average loss of ~3.7% per decade.
- Additional loss ~4.75% from 1998-2015 (27 years), average loss ~1.75% per decade.
Much of the glacier’s loss occurred before 1966, when fossil fuel warming was minimal. This early glacial loss percentage substantially exceeds the percentage loss observed in the 21st century. I suspect that much of this melting occurred in the 1930s. (see next section).
Looking back further, Glacier National Park was virtually ice-free 11,000 years ago. Glaciers have been present within the boundaries of present-day Glacier National Park since about 6,500 years ago. [link] These glaciers vary in size, tracking climate variations, but did not grow to their recent maximum size until the end of the Little Ice Age, around 1850. A period of 80 years (~ 1770-1840) with cool and wet summers – moderate snowfall in winter led to rapid growth of glaciers just before the end of the Little Ice Age. So, the recent loss of glacial mass must be understood based on the fact that glaciers have reached their largest mass in the last 11,000 years in 19 years.order century. [link]
The USGS hasn’t updated its ice survey since 2015 (have to wonder why, given the massive losses they expect). While the loss from 1998 to 2015 was down from previous decades, it appears that ice loss has actually stagnated or reversed slightly since 2008. [link] This stagnation prompted Glacier National Park in 2017 to begin removing signs that the glaciers would disappear by 2020.
So what’s going on?
The area size and mass balance of glaciers depend on the interaction between the accumulation of snow during the cold season and the melting of the glaciers during the summer. Not available prima facie the reason is that slow warming of average annual surface temperature will result in loss of glacier area/mass. Snowfall varies greatly from year to year and cyclically, and in some cases, warmer winter temperatures can lead to more snowfall. Summer meltdown is quite short. The timing of the rapid, weather-driven transition from snow to rain is a major determinant of the onset of the thaw season and thus its length. In the summer, the time of day and the overall amount of cloudiness can make a big difference in how much melting occurs. And finally, the soot associated with air pollution can provide a significant accelerator for glacier melting; this is a big deal for Hindu-Kush-Himalayan glaciers, but I don’t see any relevance to soot in the context of Glacier National Park.
You won’t be surprised to learn that ENSO, Pacific Declining Oscillation (PDO) and Atlantic Multi-peak Oscillation (AMO) influence atmospheric circulation patterns that affect both seasonal snow accumulation cold and melt in summer (For an overview see LINK)
First let’s look at the snow. During the period of instrumental snow measurement in Montana since 1955, there was an overall downward trend in April snowfall in Montana between 1955 and 2015. Since 2016, however, for most of the past seven years, spring snowfall has been normal to above normal across Montana. [link] This behavior reflects the changing nature of climate on both seasonal and decadent scales.
To expand our understanding of the behavior of past ice sheets, paleontological records have been developed to supplement modern data sources. These records include lake sediment and tree ring data. A pivotal study focusing on the American West was published in 2011, providing a record of more than 500 years of data. [LINK] This record length shows that climate variability on a century-scale includes features such as the Little Ice Age. The study also demonstrates a variety of short-term climate features that show different anomalies between the northern and southern Rockies. In particular, the study identified a snow drought during the 1930s in the Greater Yellowstone Region (Montana) similar to the low values seen in the late 20th century.
Now consider summer temperatures. Shown here are the Montana state averages from NOAA’s State Climate Summary for Montana (2022).[link] While the two decades in the 21st century have been generally the warmest for Montana since 1900, there is no trend of extreme summer temperatures. Montana’s warmest summer temperatures were in the 1930s.
Very hot days (≥95 oF) and warm nights (≥70 oF) was the highest in the 1930s.
Are there any surprises here if glacial retreat was particularly strong in the 1930s?
Montana’s Cold Winters
The “greedy” part of Reilly Neill’s tweet seems to have something to do with fossil fuels. If there’s one place you might want to stay warm on fossil fuels (or nuclear), Montana in the winter is it. Montana is one of the coldest states in the US. Of particular concern are “Arctic outbreaks” in winter, which occur several times each winter with varying intensity and duration. Periodic “Arctic flares” bring exceptionally frigid temperatures to large areas of the continental United States, even in times of global warming.
A particularly cold outbreak occurred in Montana during February and March 2019, with similar outbreaks in 2014 and 2017. In February 2019, average temperatures deviated from normal. in Montana it’s 27 to 28 oF below normal, with Great Falls at the heart of the cold. Temperature does not rise above 0 oF for 11 days and drops to 0 oF or less for 24 nights. While the February cold snap was notable for its persistence, the ensuing arctic blast in early March 2019 delivered the coldest temperatures. Nearly two dozen official stations in Montana broke monthly records, with the all-time record low for March at -46F. [link]
I can’t even imagine what it would be like without electricity and heating in the house in such cold conditions. In addition to freezing and trying to stay warm, the water pipes will freeze; Not only is it a lack of drinking water, but it also causes great damage to property when the pipes are thawed.
Fortunately, Montana has a reliable electricity system with about 50% renewable energy (mostly hydro) with most of the rest produced by coal. There is a large team in Montana looking for 100% renewable energy (hydro, wind, solar).
Aside from the special electricity demand for residential heating during such arctic outbreaks, any electricity output from renewables is minimal during those times. Montana’s solar and hydroelectric capacity is at its lowest during the winter. While winter winds are generally strong, arctic cold air outbreaks are accompanied by large areas of high pressure known as cold core convection circuits. The nature of these circulations is that the wind speed is very low in a high-pressure system, resulting in very low amounts. wind power production.
Although Arctic outbreaks typically hit the northern Great Plains states most severely, the spatial extent of these outbreaks can be enormous. A cold outbreak in February 2021 that affected Montana also covered half of the US and extended down to Texas, where a massive power outage resulted in significant loss of life. The large horizontal scale of these high-pressure systems indicates that transferring excess energy from a remote location won’t help much if much of the continent is also suffering from cold temperatures and low winds. . The long duration of these events makes battery storage extremely feasible. The options are nuclear, gas and coal.
It is not easy to understand the causes of climate change. The key to understanding is to look at the longest data records available, and try to explain the causes of historical and classical variation. Once you understand nature’s variability, it’s not easy to attribute everything to fossil fuel warming and make naive predictions about the future. And once you understand weather variability and extreme events, you won’t go overboard with renewables.
It is my hope that this little explanation will help Reilly Neill and the real scientists of Montana understand the cause of these recent variations in the glaciers of Montana.