Robust evidence from bison remains recovered from the Austrian Alps in 2020 and 2021 invalidate claims modern Alpine temperatures are unusually warm.
A new study suggests that from about 6000 to 1200 years ago European bison fed on deciduous tree/vegetation that grew at Alpine altitudes reaching around 800 m higher than they do today.
Known beech and oak tree growth warmth thresholds – the required number of days per year above a minimum temperature limit – thus affirm Austria needed to be 4-7°C warmer than now during this period (~2000 years ago).
“[T]he beech limit but also the forest line during the »wisent time« (6,000 to 1,200 years before today) was much higher and the average summer temperature had to be at least 3 to 6 °C higher than today. Remarkable is a palynological record (Ressl, 1980) from the shaft cave Stainzerkogelschaft near Lunz am See. Remains of wisent were found in the shaft (1,463 m, see Tab. 3). The clay with a skull fragment with horncores inside was examined palynologically. The dominating pollen were from alder (Alnus), oak (Quercus) and linden tree (Tilia). The oak boundary (boundary between colline and montane vegetation stages) today lies between 400 and 800 metres in the Northern Alpine Alps (Grabherr et al., 2004). Oaks (Quercus) at an altitude of 1,450 metres around 2,000 years ago also indicate a climate approximately 4 to 7 °C warmer than today.”
Image Source: Schaer et al., 2022
A 4-7°C warmer regional Holocene temperature is warmer than other estimates of an Austrian summer temperatures “3.0 to 4.5°C above the modern value” (Ilyashuk et al., 2011).