Former Vice President (1992-2000) Al Gore, who has long warned about the allegedly devastating impacts of global warming, caused by burning fossil fuels, viewed glaciers, and recent glacial retreat, as iconic evidence for his claims. He has focused in on Montana’s Glacier National Park to make that case.
In a 1997 speech in the park, Gore said: “Jackson Glacier has lost about 75% of its surface area. If this trend continues, in about thirty years, there won’t be any glaciers left at all. To borrow a phrase from a well-known pop musician, this could become be the Park Formerly Known as Glacier.
“What’s happening at Glacier National Park is strong evidence of global warming over the past century — the disruption of our climate because of greenhouse gas emissions into the atmosphere, all over the world.”
But climatologist Judith Curry, a skeptic about the most apocalyptic effects of climate change, recently criticized the emphasis on what’s happening with glaciers as evidence of mankind’s assault on the globe, using the national park as a case of overstatement. Curry is professor Emeritus and former Chair of the School of Earth and Atmospheric Sciences at Georgia Tech. She’s a long-standing skeptic of some of the scientific claims advanced by warming advocates.
Some of the most extreme believers of the notion that global warming is the most serious threat to life as we know it on earth have attacked Curry. She does not deny global warming but says there are natural causes that contribute. She and Michael Mann, who succeeded Curry at Penn State’s Department of Meteorology and is now director of the Center for Science, Sustainability & the Media at the University of Pennsylvania and among the hard liners on warming, have battled repeatedly and publicly.
For Curry, the key to the melting of namesakes of Glacier National Park, and glacial retreats elsewhere, started around 1850, well before industrial greenhouse gases, particularly carbon dioxide, were a significant factor in the Earth’s atmosphere. The park’s glaciers, present since around 6,500 years ago, reached their maximum size during the “80-year period (~1770-1840) of cool, wet summers and above-average winter snowfall,” known as the Little Ice Age, or LIA, she writes.
Curry cites a 2017 U.S. Geological Survey study, “Status of Glaciers in Glacier National Park”, which mapped the extent of the glaciers in “1966, 1998, 2005 and 2015/2016, marking 49 years of change for most of the glaciers and 50 years of change for a few.” Curry notes that the USGS data shows:
- A ~50% loss from LIA to 1966 (~115 years), averaging a loss of ~4.5% per decade.
- Additional ~12% loss from 1966-98 (32 years), averaging a loss of ~3.7% per decade.
- Additional ~4.75% loss from 1998-2015 (17 years), averaging a loss of ~2.8% per decade.
“Much of the glacier loss occurred prior to 1966,” according to Curry, “when fossil-fueled warming was minimal. The percentage rate of glacier loss during this early period substantially exceeded the percentage rate of loss observed in the 21st century.” She added that “it appears that the ice loss has actually stalled or slightly reversed since 2008. This stall caused the Glacier National Park in 2017 to start taking down the signs that expected the glaciers to disappear by 2020.”
Curry concludes, “Nothing is simple when it comes to understanding the causes of climate change impacts. The key to understanding is to look at the longest data records available, and try to interpret the causes of the historical and paleo variability. Once you understand the natural variability, you aren’t so prone to attributing everything to fossil-fueled warming and making naïve predictions of the future.”