Human activity pushes biodiversity toward a historic crossroads
New research suggests that human activity is triggering an extinction episode on a scale not seen since the dinosaur era. While not yet classified as a true mass extinction, scientists say the current rate of species loss is extraordinarily high and could become irreversible if biodiversity loss continues unchecked. The study consolidates decades of environmental data and expert workshops to compare today’s declines with the fossil record.
The work, conducted by researchers at the Leverhulme Centre for Anthropocene Biodiversity and colleagues, emphasizes that the pace and pervasiveness of change are unprecedented in the last 66 million years. Yet the researchers stress that the trajectory is not predetermined; human choices can alter outcomes through policy, conservation, and behavior changes.
Tracing the roots of the crisis
Scientists trace human-driven extinction signals back roughly 130,000 years, tied to the global spread of Homo sapiens and the sequential vanishing of large-bodied animals. Early losses included mammoths, giant ground sloths, and island endemics. In more recent times, species such as the Tasmanian tiger and Steller’s sea cow have disappeared, underscoring a pattern of rapid decline in a broad range of habitats.
The study contrasts these modern dynamics with the most famous ancient extinction—the asteroid-induced loss at the end of the Cretaceous. That event eliminated an enormous share of species in a relatively short window. Today, although many groups are suffering substantial losses, the speed and scale do not match the asteroid’s catastrophic tempo.
Which past events resemble today’s losses?
Among historical comparisons, the Eocene–Oligocene extinction about 34 million years ago emerges as the most analogous in the record of biodiversity declines. That period involved global cooling and ice-sheet growth in the Antarctic, reshaping ecosystems over millions of years. The current, human-fueled changes are far more abrupt, occurring within a geologically short span of centuries to millennia.
Experts caution that although the Eocene–Oligocene episode pre-dates humans, the present impact of anthropogenic pressures—habitat loss, climate change, overexploitation, invasive species—has intensified the rate at which chaos unfolds in ecosystems. This distinction is crucial: it points to human responsibility and the ability to alter the outcome through deliberate action now.
Key takeaways from the analysis
The researchers emphasize several important conclusions:
- Current extinction rates are extraordinarily high, with many lineages already lost and others hanging in precarious balance.
- While not yet a mass extinction, the ongoing losses could reach that threshold if trends continue, especially given accelerating environmental change.
- Unlike past natural events, today’s driver is directly tied to human activity, making policy responses and conservation efforts uniquely impactful.
Dr. Jack Hatfield, a leading figure in the study, notes that “the pace of change we’re seeing today is unlike anything we know of in the past 66 million years, but crucially, it’s not too late. We still have the power to decide how that story ends.”
What science asks of policy and the public
The report calls for urgent actions to reduce environmental harm, preserve critical habitats, and curb drivers of biodiversity loss. It also highlights the challenges in comparing present-day trends with deep-time records, due to gaps in the fossil record, undiscovered species, and extinctions that go unnoticed in real time.
Ultimately, the study presents a nuanced, evidence-based narrative: human influence has become a defining force in Earth’s history, but effective, immediate interventions could still reshape the trajectory away from a future marked by mass biodiversity loss.
Published in Global Change Biology, the research invites a broader dialogue about how societies value nature and what steps are necessary to safeguard the planet’s remaining diversity for future generations.
