Climate story · Bonn, Germany
Spreading of thermophilic species in my hometown
A lasting childhood vacation memory for me is when we used to catch praying mantises in jam jars in dry meadows of the French Provence while cicadas were chirping over our heads. 10-15 years ago, the Mediterranean climate of this region didn‘t feel remotely comparable to my home region in west Germany so you could say I was super unpleasantly surprised when I spotted two praying mantises in one week in not-so-mediterranean Bonn.
For comparison you can look at growing degree days (the sum of how much warmer each day is than the ~10 °C that insects need to grow, added up across the season). Bonn reaches only around 1,000 a year, half the roughly 1,900 of southern France, (where the mantis has its core range). And yet those 1,000 are already enough to carry the species past the warmth it needs to survive a season here, a threshold which Bonn had not reached a decade ago. Tiger mosquitoes are already becoming popular here, but this was a new one for me.
The data behind this story: in Bonn, the last ten years averaged +1.9 °C against the 1961–1990 normal; yearly rainfall changed by +8 %; the drought index stands at −1.9. See 75+ years of climate data for Bonn, Germany →