Climate change will be the main cause of biodiversity decline

The change in land use in the 20th century caused a loss of biodiversity world of between 2% and 11% and, if things do not change, everything indicates that by the middle of this century, the climate change will be the main cause of global environmental decline.

This is indicated by the largest modeling study of this type carried out to date, a work led by the German Center for Integrative Biodiversity Research (iDiv) and the Martin Luther University of Halle-Wittenberg (MLU), whose conclusions have been published this Thursday in Science magazine.

The team compared 13 models to assess the impact of land use change and climate change on four different biodiversity parameters and nine ecosystem services.

And, according to the Intergovernmental Platform on Biological Diversity and Ecosystem Services (IPBES) created by the United Nations, change in land use is the main driver of change in biodiversity, but scientists do not agree about how much biodiversity has changed in recent decades.

To clarify this, researchers from iDiv and MLU modeled the effects of land use change on biodiversity throughout the 20th century and found that global biodiversity could have decreased between 2% and a eleven% due ‘exclusively’ to the change in land use.

To arrive at these percentages, the team analyzed four biodiversity parameters calculated using seven different models.

“By including all regions of the world in our model, we have been able to fill many blind spots and respond to criticism of other approaches that work with fragmented and potentially biased data”says Henrique Pereira, first author and head of the research group.

“Each approach has its advantages and disadvantages. “We believe that our modeling approach provides the most comprehensive estimate of biodiversity trends around the world,” the researcher maintains.

Ecosystem services

Using another set of five models, the researchers also calculated the simultaneous impact of land use change on so-called ecosystem services, that is, the benefits that nature provides to humans.

In the last century, there has been a massive increase in provisioning ecosystem services, such as food and wood production. On the other hand, regulating ecosystem services, such as pollination, nitrogen retention or carbon sequestration, decreased moderately.

The researchers also examined how biodiversity and ecosystem services might evolve in the future and for these projections, they added climate change as a growing driver of biodiversity change to their calculations.

The results indicate that climate change could put additional pressure on biodiversity and ecosystem services, and although land use change remains important, climate change could become the main driver of biodiversity loss by 2050.

In addition, the team evaluated three scenarios, from sustainable development to high emissions, and in all of them, the combined effects of land use change and climate change cause a loss of global biodiversity (although with considerable variations between the different regions of the world, models and scenarios).

Projections, not predictions

The goal of long-term scenarios “It is not predicting what is going to happen”but to understand the alternatives to try to avoid “the least desirable trajectories” and choose well “the policies and decisions that are made every day”, says co-author Inês Martins of the University of York.

Furthermore, according to the researchers, evaluating the impact of specific policies on biodiversity helps identify the most effective policies to safeguard and promote biodiversity and ecosystem services.

“There is no doubt that there are uncertainties in the modeling” but still “Our findings clearly show that current policies are insufficient to achieve international biodiversity goals. We need renewed efforts to make progress against one of the world’s biggest problems, which is human-caused biodiversity change.”, warns Pereira.

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