From land use to climate change: The looming shift in biodiversity loss

Global biodiversity declined by approximately 2-11 percent in the 20th century, primarily due to changes in land use. According to a report published in the journal Science, climate change is projected to become the main culprit behind biodiversity loss in the first half of the 21st century.

The report highlights the findings of an extensive international study (https://doi.org/10.1126/science.adn3441), which assessed the impacts of thirteen different land use and climate change models across four biodiversity indicators and their effects on nine ecosystem services.

Currently, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) identifies land use as the most significant factor influencing biodiversity loss. Experts worldwide, however, are debating the extent of this diversity's change over recent decades.

To address this, researchers explored various scenarios and relationships, concluding that global biodiversity has diminished by 2 to 11 percent in the last century solely due to changes in land use.

"Our model included all global regions, uncovering many previously unknown aspects using qualitative data," explains Prof. Henrique Pereira, the study's lead author. "We believe this provides the most comprehensive estimate of worldwide biodiversity trends available."

The study also evaluated how changes in land use have affected ecosystem services or the benefits nature offers humans. Over the 20th century, there was a significant increase in ecosystem services related to production, like food and wood, while regulating services such as pollination, nitrogen retention, and carbon sequestration saw moderate declines.

Additionally, the research team looked at potential future biodiversity and ecosystem services changes, factoring in climate change as a key driver. Their findings indicate that climate change will exacerbate the stresses on biodiversity and ecosystem services. While land use remains a critical issue, global warming could soon emerge as the primary factor behind biodiversity loss. All scenarios explored, from those envisioning sustainable development to high-emission futures, predict a consistent global decrease in biodiversity.

"Testing long-term models aims to explore alternatives, helping us avoid unwanted outcomes and guide us towards more favorable ones. The paths we take depend on our policies and daily decisions," Dr. Inês Martins from the University of York, a study co-author, shared.

The researchers also pointed out that even the most sustainable scenarios failed to consider all possible policies that could be enacted in the coming decades. For instance, no measures were included to enhance the efficiency and extent of protected areas or ambitious rewilding initiatives.

"Despite various uncertainties, our results indicate that current policies are insufficient for meeting global biodiversity targets. We urgently need innovative strategies to address one of humanity's most pressing challenges: the ongoing biodiversity loss due to human activities," concluded Prof. Pereira.