The unprecedented expansion of human activities into vast areas of our planet in the 20th century reduced biodiversity globally by 2 to 11 percent, depending on the data source and calculation method, as researchers show in the journal Science. While the reason for the decline in biodiversity previously lay primarily in changes or intensification of land use, advancing climate change is likely to become the main driver by the middle of the 21st century.
It is undisputed that the human hunger for more and more previously relatively natural areas has become ever greater in recent decades. The World Biodiversity Council (IPBES) also sees changed land use as the biggest factor that profoundly changes the composition of species and reduces their diversity. The decline in biodiversity is now seen as one of the biggest problems of the future.
Global warming is overtaking land use
According to the comprehensive analysis led by the German Center for Integrative Biodiversity Research (iDiv) and the University of Halle-Wittenberg (MLU), it is to be expected that global warming will overtake land use from its dubious status. The team, which also included scientists from the International Institute for Applied Systems Analysis (IIASA) in Laxenburg near Vienna and Michael Obersteiner from the Environmental Change Institute at the University of Oxford (Great Britain), has now presented the most comprehensive analysis on the topic to date, it is said on the part of IIASA.
A look at the past century once once more revealed the massive increases in food and wood production – the practice of extracting resources from nature for the benefit of humans, as scientists put it. At the same time, the diverse data also shows how factors that keep the ecosystem in balance, such as pollination of plants or the ability to store nitrogen and carbon in nature, have declined.
A look into the future
If the scientists directed their analyzes towards the future, “our findings suggest that climate change can replace changes in land use as the primary driver of biodiversity loss by the middle of the century,” IIASA researcher David Leclère is quoted as saying in a press release.
If the effects of land use changes and those of climate change were taken into account in combination, the results were – depending on the model assumptions – biodiversity declines of between just under one and five percent per decade worldwide. If the temperature increase were limited to two degrees Celsius, the decrease in biodiversity would be 40 to 74 percent lower than in a scenario without greenhouse gas containment measures, the scientists write in their paper.
Weigh up measures
In any case, balancing measures that are intended to contribute to the energy transition, such as expanding the production of energy from biomass, and measures to protect biodiversity is not easy: bioenergy is often viewed as an important component in stabilizing the climate. But this requires large areas used for agriculture and forestry once more, “which poses a danger to special habitats,” says Petr Havlík, one of the co-authors of the study.
Overall, the findings from the study are a further argument for defining and implementing regional goals to protect biodiversity and for promoting the renaturation of areas as a natural climate protection measure. Unfortunately, it is also clear to see that the current policy has failed to solve one of the “biggest problems of humanity”.
