Land Use Change Blamed for Up to 11 % Global Biodiversity Decline

A comprehensive multi-model study published in Science, led by the German Centre for Integrative Biodiversity Research (iDiv) and the Martin Luther University Halle-Wittenberg (MLU), reveals that global biodiversity decreased by 2 % to 11 % solely due to land-use changes in the 20^th century. Projections indicate that climate change could emerge as the primary catalyst for biodiversity decline by the mid-21^st century.

The analysis represents the most extensive modeling study of its kind to date. Researchers evaluated 13 models to assess the influence of both land-use change and climate change on four distinct biodiversity metrics, as well as on nine ecosystem services.

Global Biodiversity May Have Declined By 2 % to 11 % Due to Land-Use Change Alone

According to the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), land-use change is the primary driver of biodiversity alteration. Scientists have debated the extent of biodiversity changes in recent decades.

To provide more clarity, the researchers modeled the effects of land-use change on biodiversity throughout the 20^th century. Their findings suggest that global biodiversity may have decreased by 2 % to 11 % solely due to land-use change. This range encompasses calculations of four biodiversity metrics conducted by seven distinct models.

By including all world regions in our model, we were able to fill many blind spots and address criticism of other approaches working with fragmented and potentially biased data. Every approach has its ups and downsides. We believe our modeling approach provides the most comprehensive estimate of biodiversity trends worldwide.

Henrique Pereira, Study First Author, Professor and Research Group Head, German Centre for Integrative Biodiversity Research

Henrique Pereira is also associated with MLU.

Mixed Trends for Ecosystem Services

Using an additional set of five models, the researchers assessed the concurrent effect of land-use change on ecosystem services, referring to the benefits nature offers humans. Over the past century, they observed a substantial rise in “provisioning” ecosystem services, such as food and timber production. In contrast, “regulating” ecosystem services, such as pollination, nitrogen retention, or carbon sequestration, experienced a moderate decline.

Climate and Land-Use Change Combined Might Lead to Biodiversity Loss in All World Regions

The researchers investigated the potential evolution of biodiversity and ecosystem services in the future. For these projections, they incorporated climate change as an increasing factor influencing biodiversity change into their calculations.

According to the findings, climate change is poised to exacerbate pressure on biodiversity and ecosystem services. While land-use change remains significant, climate change could emerge as the primary driver of biodiversity decline by mid-century. The researchers evaluated three commonly used scenarios, ranging from sustainable development to high emissions.

Across all scenarios, the combined impacts of land use and climate change contribute to biodiversity loss in all global regions. Although the overall downward trajectory remains consistent, notable variations exist across world regions, models, and scenarios.

Projections are Not Predictions

The purpose of long-term scenarios is not to predict what will happen. Rather, it is to understand alternatives, and therefore avoid these trajectories, which might be least desirable, and select those that have positive outcomes. Trajectories depend on the policies we choose, and these decisions are made day by day.

Dr. Inês Martins, Study Co-Author, University of York

Martins co-led the model analyses and is an alumna of iDiv and MLU.

The researchers also highlight that even the most sustainable scenario evaluated does not fully utilize all potential policies to safeguard biodiversity in the upcoming decades. For example, while bioenergy deployment, a significant element of the sustainability scenario, can aid in climate change mitigation, it can also diminish species’ habitats.

Conversely, strategies aimed at enhancing the effectiveness and extent of protected areas or implementing large-scale rewilding initiatives were not investigated in any of the scenarios.

Models Help Identify Effective Policies

The researchers suggest that evaluating the effects of specific policies on biodiversity aids in identifying the most effective measures for protecting and enhancing biodiversity and ecosystem services.

There are modeling uncertainties, for sure. Still, our findings clearly show that current policies are insufficient to meet international biodiversity goals. We need renewed efforts to make progress against one of the world’s largest problems, which is human-caused biodiversity change.

Henrique Pereira, Study First Author, Professor and Research Group Head, German Centre for Integrative Biodiversity Research

Journal Reference:

Pereira, H. M., et al. (2024). Global trends and scenarios for terrestrial biodiversity and ecosystem services from 1900 to 2050. Science. doi.org/10.1126/science.adn3441