NOVEMBER 6, 2021
By Paul Homewood
Justin Rowlatt, brother of Insulate Britain loon Cordelia, has flown to Alaska now to complain about melting glaciers:
He visited the famous Portage Glacier to make his point.
It’s a pity the useless Rowlatt did not do his homework first. It is well established amongst glaciologists that glaciers in Alaska expanded massively during the Little Ice Age. Indeed, the remains of forests now being uncovered by receding glaciers, dated back to the Middle Ages, show that glaciers then were much less extensive than now.
It is also known that modern glacial retreat began in the 19thC, long before any supposed impact from AGW, which Rowlatt wants to blame.
I did a detailed analysis of the Portage Glacier two years ago, following Michael Portillo’s filming there of his series Great Railroad Journeys. I won’t copy it in full, but you can see it here. The salient points are below.
To recap, Michael Portillo’s railway journeys are based around the Appleton’s travel guides from the 19thC. There was even one for Alaska, which included this gem:
“Old residents insist that the climate is changing. That the summers are warmer and drier. The rapid retreat of all the glaciers during even 20 years is offered as another proof.”
The guide was published in 1899, so this is good evidence that glacier retreat began long before even then.
The US Geological Survey confirms that the Portage Glacier itself has been receding since at least 1914, and that the fastest retreat occurred between 1939 and 1950:
During the late 1800s and early 1900s, Portage Glacier terminated on land at the western end of Portage Lake, filling Portage Lake with ice (Photo Plate 1914). Since the early 1900s, the glacier has receded, leaving Portage Lake in the scoured basin. The initial retreat of the glacier coincides with known climate warming associated with the end of the Little Ice Age (circa mid-19th century). As the glacier receded, its land-based terminus retreated into proglacial Portage Lake and changed from its relatively stable land-based environment to an unstable calving environment. The most rapid recession of some 140 to 160 meters per year occurred between 1939 (Photo Plate, 1939) and 1950, when water depth at the terminus was at its maximum—roughly 200 meters. Recession continued through the 1970s and 1980s (Photo Plate, 1972, 1984) until by late 1999, Portage Glacier had receded almost 5 kilometers, to a more stable position at the eastern end of Portage Lake (Photo Plate, 1999). The retreat was driven primarily by calving of unstable ice at the glacier terminus into Portage Lake. Ice loss resulting from increased melting of the glacier surface during the past century-long general warming trend contributed to glacier retreat, but to a lesser extent. Today, the terminus of Portage Glacier remains close to its 1999 location.
As I wrote at the time:
Many scientists have closely measured and studied glaciers throughout Alaska, and the conclusions have always been the same. Alaskan glaciers, which grew enormously during the Little Ice Age, began rapid retreat during the 19thC.
But it is fascinating that this was all common knowledge to a writer of a tourist guidebook published in 1899.
That writer evidently knew more about Alaskan glaciers than Justin Rowlatt does now!
via Watts Up With That?
November 6, 2021 at 01:00PM