Urbanisation and global warming: a deadly cocktail for butterflies
A study of trends in 8,400 populations of 145 species in 12 European countries shows that the combination of climate change and urbanisation is a dangerous cocktail for butterflies.
Global warming and the increased frequency of extreme weather events (prolonged drought, heavy rainfall) exacerbate other pressures such as habitat loss and fragmentation and nitrogen excess, leading to a decline in butterfly populations across Europe. However, this trend is significantly more negative in urbanised areas such as Flanders and the Netherlands than in more rural environments. Due to a lack of parks and nature-friendly gardens and the presence of a lot of paved surfaces, cities experience a heat island effect. As a result, butterflies can no longer find cool places to rest and are more likely to die.
Some butterfly species are more sensitive to this than others. Cold-loving species, species with a short flight period or with only one generation per year, and species tied to a single host plant are declining significantly faster due to the amplifying effect of urbanisation on climate change. To halt the decline of butterflies in particular and insects in general, it is not enough to look at the climate alone. Urban landscapes must also be redesigned. Greater connectivity between nature areas and the creation of green (thermal) buffers in the city are essential for the conservation of butterflies in an urbanised environment.
Image above: Ringlet, a cold-loving grassland species that prefers slightly damp conditions.
This butterfly is affected by both urbanisation and global warming (photo: Valérie Goethals)