75% Of Total Modern Glacier Melt Occurred Before 1950
“[T]he retreat of the glaciers after about 1925 became rapid. It was almost entirely during the [pre-1950] twentieth century warming that the Alpine glaciers disappeared from the valley floors up into the mountains. Similarly great retreats occurred in Scandinavia, Iceland, Greenland, in the Americas, and on high mountains near the equator.” — H.H. Lamb Climate, History, and the Modern World (1982), pg. 248
A new scientific paper indicates that the pronounced warming that occurred during the years stretching from the 1920s to the 1940s melted Northern Iceland glaciers much more extensively and at a far more rapid pace than has been observed in recent decades.
During the 1960s to 1980s, glacier melt rates not only decelerated relative to the 1920s to 1940s, the ice actually advanced in some cases due to decades of cooling. It has only been since about the mid-1990s that glaciers have consistently begun melting again — but with far less alacrity than they did in the first half of the 20th century.
Fern√°ndez-Fern√°ndez and co-authors (2017) indicate that the Icelandic glaciers they studied melted by more than 1,000 meters (1,062) on average between the late 1800s and 1946. But from 1947 to 2005, these same glaciers only retreated by an average of 272 meters more. In other words, about 75% of the total glacier melt production since the end of the Little Ice Age (the late 19th century) occurred prior to the mid-1940s.
Below are some key points and graphs from the paper.