According to the study published in Science, global biodiversity has declined by two to 11 per cent in the 20th century due to changes in land use alone. The comprehensive modelling calculations of the international team of researchers also show that climate change could become the main reason for the decline in biodiversity by 2050. "Until now, land use due to the use of soil and land by humans was considered the main cause. For the first time, this study has now provided a global perspective on the complex development of biodiversity. This is a major step forward for our field of research and brings the effects of the climate crisis into play as a central factor for the future," emphasises Lauren Talluto from the Fluvial Ecosystem Ecology research group at the Department of Ecology at the University of Innsbruck. In her work, Talluto is involved in modelling the trends in biodiversity and is particularly interested in the effects of climate change in this context.
Global trends for biodiversity
The work, led by the German Centre for Integrative Biodiversity Research (iDiv) and Martin Luther University Halle-Wittenberg (MLU), is the most comprehensive modelling study of its kind to date. The research team compared thirteen models that calculate the effects of land use and climate change on four different measures of biodiversity and nine different ecosystem services. According to the World Biodiversity Council IPBES, land-use change, for example the conversion of forest to cattle pasture, is the most important factor in biodiversity change. However, measuring the extent to which biodiversity has changed is still a major challenge for scientists. The team of researchers therefore modelled the effects of land use change on biodiversity in the 20th century. "By including all regions of the Earth in our model, we were able to fill in many blind spots. We were also able to address the critiques of other calculation approaches that use fragmented and possibly unrepresentative data," says first author Henrique Pereira, research group leader at iDiv and MLU.
Effects on ecosystem services
The team used five different models to calculate the effects of land use change on ecosystem services as part of this study. For the past 20th century, the researchers found that provisioning services, such as food and timber production, have multiplied, while regulating services - such as pollination by insects or the sequestration of climate-relevant carbon - have declined moderately. However, the study also looked into the future up to 2050 and the authors included climate change as an additional factor in their models. According to these calculations, the consequences of climate change will have an additional negative impact on both biodiversity and ecosystem services. While land-use change continues to play an important role, climate change could become the main cause of biodiversity loss by the middle of the 21st century. The team assessed three current climate scenarios, ranging from sustainable development to very high emissions, and concluded that land-use change and climate change together will lead to a decline in all regions of the world, even if the details inevitably differ in the various world regions, models and scenarios. "The results once again make it very clear that globally coordinated action is urgently needed to mitigate the consequences of the climate crisis and that the protection of biodiversity should be a top priority if only to preserve ecosystem services that are crucial for survival," emphasises Lauren Talluto.
Publication:
Henrique M. Pereira et al. Global trends and scenarios for terrestrial biodiversity and ecosystem services from 1900 to 2050. Science 384, 458-465(2024). DOI: 10.1126/science.adn3441