Climate change could become the main driver of biodiversity decline by mid-century

Climate change could become the main driver of biodiversity decline by mid-century, according to a new study published in Science (Picture: Oliver Thier)

Land-use change has been considered the largest driver of biodiversity decline in the 20th century. The photo shows an intensively managed grain field in Germany (Picture: Guy Pe’er)

Land-use change is, for example, the conversion of forest into farmland or pasture. It has contributed significantly to biodiversity decline in the 20th century and today. The photo was taken in the Amazon (Picture: Marcio Isensee e Sá - stock.adobe.com)

Note for the media: Use of the pictures provided by iDiv is permitted for reports related to this media release only, and under the condition that credit is given to the picture originator.

Largest modelling study of its kind, published in Science

Global biodiversity has declined between 2% and 11% during the 20th century due to land-use change alone, according to a large multi-model study published in Science. Projections show climate change could become the main driver of biodiversity decline by the mid-21st century. 

The analysis was led by the German Centre for Integrative Biodiversity Research (iDiv) and the Martin Luther University Halle-Wittenberg (MLU) and is the largest modelling study of its kind to date. The researchers compared thirteen models for assessing the impact of 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

Land-use change is considered the largest driver of biodiversity change, according to the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES). However, scientists are divided over how much biodiversity has changed in past decades. To better answer this question, the researchers modelled the impacts of land-use change on biodiversity over the 20th century. They found global biodiversity may have declined by 2% to 11% due to land-use change alone. This span covers a range of four biodiversity metrics¹ calculated by seven different 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,” says first author Prof Henrique Pereira, research group head at iDiv and MLU. “Every approach has its ups and downsides. We believe our modelling approach provides the most comprehensive estimate of biodiversity trends worldwide.”

MIXED TRENDS FOR ECOSYSTEM SERVICES

Using another set of five models, the researchers also calculated the simultaneous impact of land-use change on so-called ecosystem services, i.e., the benefits nature provides to humans. In the past century, they found a massive increase in provisioning ecosystem services, like food and timber production. By contrast, regulating ecosystem services, like pollination, nitrogen retention, or carbon sequestration, moderately declined.

CLIMATE AND LAND-USE CHANGE COMBINED MIGHT LEAD TO BIODIVERSITY LOSS IN ALL WORLD REGIONS

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

Climate change stands to put additional strain on biodiversity and ecosystem services, according to the findings. While land-use change remains relevant, climate change could become the most important driver of biodiversity loss by mid-century. The researchers assessed three widely-used scenarios – from a sustainable development to a high emissions scenario. For all scenarios, the impacts of land-use change and climate change combined result in biodiversity loss in all world regions. While the overall downward trend is consistent, there are considerable variations across world regions, models, and scenarios.

PROJECTIONS ARE NOT PREDICTIONS

“The purpose of long-term scenarios is not to predict what will happen,” says co-author Dr Inês Martins from the University of York. “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.” Martins co-led the model analyses and is an alumna of iDiv and MLU.

The authors also note that even the most sustainable scenario assessed does not deploy all the policies that could be put in place to protect biodiversity in the coming decades. For instance, bioenergy deployment, one key component of the sustainability scenario, can contribute to mitigating climate change but can simultaneously reduce species habitats. In contrast, measures to increase the effectiveness and coverage of protected areas or large-scale rewilding were not explored in any of the scenarios

MODELS HELP IDENTIFY EFFECTIVE POLICIES

Assessing the impacts of concrete policies on biodiversity helps identify those policies most effective for safeguarding and promoting biodiversity and ecosystem services, according to the researchers. “There are modelling uncertainties, for sure,” Pereira adds. “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.”

¹global species richness, local species richness, mean species habitat extent, biodiversity intactness

Volker Hahn

This research was financed inter alia by the Deutsche Forschungsgemeinschaft (DFG; FZT-118).

Original paper
(Researchers with iDiv affiliation and alumni bolded)
Henrique M. Pereira, Inês S. Martins, Isabel M.D. Rosa, HyeJin Kim, Paul Leadley, Alexander Popp, Detlef P. van Vuuren, George Hurtt, Luise Quoss, Almut Arneth, Daniele Baisero, Michel Bakkenes, Rebecca Chaplin-Kramer, Louise Chini, Moreno Di Marco, Simon Ferrier, Shinichiro Fujimori, Carlos A. Guerra, Michael Harfoot, Thomas D. Harwood, Tomoko Hasegawa, Vanessa Haverd, Petr Havlík, Stefanie Hellweg, Jelle P. Hilbers, Samantha L. L. Hill, Akiko Hirata, Andrew J. Hoskins, Florian Humpenöder, Jan H. Janse, Walter Jetz, Justin A. Johnson, Andreas Krause, David Leclère, Tetsuya Matsui, Johan R. Meijer, Cory Merow, Michael Obersteiner, Haruka Ohashi, Adriana De Palma, Benjamin Poulter, Andy Purvis, Benjamin Quesada, Carlo Rondinini, Aafke M. Schipper, Josef Settele, Richard Sharp, Elke Stehfest, Bernardo B. N. Strassburg, Kiyoshi Takahashi, Matthew V. Talluto, Wilfried Thuiller, Nicolas Titeux, Piero Visconti, Christopher Ware, Florian Wolf, Rob Alkemade (2024). Global trends and scenarios for terrestrial biodiversity and ecosystem services from 1900 to 2050. Science 384, 458-465. DOI: 10.1126/science.adn3441

Contact:

Prof Dr Henrique Miguel Pereira(speaks English and Portuguese)
Head of Biodiversity Conservation research group
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Martin Luther University Halle-Wittenberg (MLU)
Email: henrique.pereira@idiv.de
Web: www.idiv.de/en/profile/132.html

Dr Volker Hahn
Head of Media and Communications
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig
Phone: +49 341 97 33154
Email: volker.hahn@idiv.de
Web: www.idiv.de/media