The biodiversity of Europe today is largely linked to environmental conditions decades ago, according to a new large-scale study in the Proceedings of the National Academy of Sciences (PNAS). Looking at various social and economic conditions from the last hundred years, scientists found that today's European species were closely aligned to environmental impacts on the continent from 1900 and 1950 instead of more recent times. The findings imply that scientists may be underestimating the total decline in global biodiversity, while future generations will inherit a natural world of our making.
"The progressive impact of environmental degradation on the loss of global biodiversity is strongly linked to key socioeconomic indicators such as human population size, land use, and gross domestic product (GDP). However, species populations do not necessarily respond immediately to environmental degradation but might do so with a delay," the scientists write. This theory is known as 'extinction debt,' whereby it takes species several of their generations to show the full impact of habitat loss and other threats.
To test this theory, thirteen researchers looked at a broad array of threatened species (mammals, reptiles, fish, plants, dragonflies, and grasshoppers) across 22 European countries. Currently around 20-40 percent of these species are listed as threatened by the IUCN Red List. But the researchers found that some of the species groups—i.e. plants, dragonflies, and grasshoppers—were most closely aligned to European conditions of over a century ago: circa 1900. For mammals and reptiles, both 1900 and 1950 were most reflective, while fish was actually best correlated with contemporary conditions.