Since the early nineties of the last century, wood and peat has been found in front of several of the retreating Alpine glaciers. These indicate that since the last ice age the glaciers have retreated further than in the present.
Symbol image for wood and peat findings
The publication [
19> gives a good overview of the peat and wood finds. ("Holz- und Torffunde als Klimaindikatoren: Alpen ohne Gletscher", German, 2004, Prof. Christian Schlüchter and Ueli Jörin).
In the publication it can be read that glacier tongues were at least 300m higher between 1900 and 2300 years ago than today (Today = publication of the article Schlüchter/Jörin = 2004). This statement will still be used in comments on current global warming in 2020.
The following facts should not be forgotten:
1) Glacier melt since 2004
Since 2004 the glaciers have lost a lot of length and mass. The glacier tongues have retreated accordingly and, depending on the glacier, are much higher than in 2004. Example: The glacier end of Stei glacier (Swiss Alps) was at an altitude of 1935m in 2004 (Reference: Journey through time on www.admin.ch). In 2018 the end of the glacier was at an altitude of 2135m (Reference: map.admin.ch and own GPS measurements). This means that since the publication of the article in 2004, the tongue of the Steigletscher has retreated by 200 metres in altitude by 2018.
The tongues of other glaciers probably retreated further upwards than the Stei glacier (e.g. Oberer Grindelwaldgletscher and Turtmann glacier), while the tongues of other glaciers remained practically at the same height (e.g. Rhone glacier, Unteraar glacier and Gorner glacier).
It is therefore not entirely correct to use in 2020 the height figures (difference between then and now) from 2004.
2) Inertia/reaction time of glaciers
Glaciers have long to very long reaction times depending on their size. It takes up to several decades before glaciers noticeably melt in the event of a temperature increase (global warming). If the temperature stabilises after an increase, it will take up to several decades for the glacier to reach the level of the new temperature. Until then it loses mass and length. It retreats to higher altitudes.
We are currently in a phase in which the temperature (annual average) is rising unusually fast. The sluggish glaciers cannot keep up with this pace. For the prevailing temperatures they reach too far down into the valleys and have too much mass.
It is therefore possible that today (2020) it is already as warm or warmer than it was, when the trees grew, whose wood was freed by the glaciers.