Climate change to overtake land use as top threat to global biodiversity
Global biodiversity in the 20th century dropped by approximately 2-11 per cent, mainly due to changes in land use. Forecasts indicate that in the first half of the 21st century, climate change will be the primary cause of its loss - reports the journal "Science".
Its pages presented the results of a large, international study (https://doi.org/10.1126/science.adn3441), which compared the impact of thirteen different land use and climate change models on four different biodiversity indicators and on nine ecosystem services.
Currently, according to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), land use is considered the most important factor affecting biodiversity loss. World experts, however, are divided on how much this diversity has changed over the past decades.
To answer this question, researchers tested various scenarios and dependencies, which enabled them to determine that global biodiversity has decreased from 2 to 11 percent due to land use change alone in the past century.
"By including all regions of the world in our model, we were able to identify many previously unknowns using qualitative data," says the study's lead author, Prof. Henrique Pereira. "We believe that this is the most comprehensive estimate of worldwide biodiversity trends."
As part of the same study, scientists also calculated the impact of land use change on so-called ecosystem services, that is, the contribution of natural ecosystems to the broadly understood well-being of people. or, the benefits that nature provides to humans. It turned out that over the 20th century, there was a significant increase in the provisioning of production ecosystem services, such as food and wood production; at the same time, regulating ecosystem services, for example, pollination, nitrogen retention, or carbon sequestration, have moderately worsened.
The researchers also investigated how biodiversity and ecosystem services might evolve in the future. For these forecasts, they added climate change as a growing force driving biodiversity change into their models.
The results showed that climate change will further strain biodiversity and ecosystem services. Although land use change remains important, global warming may soon become the most critical factor causing biodiversity loss. In all tested scenarios - from sustainable development to high-emission - the combined impact of land use and climate change leads to a clear loss of biodiversity across all world regions.
"The aim of testing long-term models is not to predict what will happen, but rather to understand the alternatives, which enables us to avoid the least desired scenarios and steer towards those with positive effects. These scenarios depend on the policies we choose and the decisions we make every day," said co-author of the article Dr. Inês Martins from the University of York.
The researchers also note that even the most sustainable scenario does not include all possible policies that could be implemented in the coming decades. For example, none of them accounted for actions aimed at increasing the efficiency and scope of protected areas or leading to rewilding on a large scale.
"There are certainly various unknowns. However, our findings clearly show that the current policy is insufficient to achieve international goals for biodiversity. We need new ideas to make progress in addressing one of the world’s biggest challenges, which is the loss of biodiversity caused by humans," Prof. Pereira summarized.
