Overview

• The Planetary Health Check 2025 identifies climate change, biosphere integrity, land‑use change, freshwater change, disrupted nitrogen and phosphorus cycles, novel entities, and ocean acidification as beyond safe limits.
• Ocean acidification is newly classified as exceeded, reflecting declining seawater pH from human‑driven CO2 uptake intensified by deforestation and land‑use change.
• Observed impacts include mounting stress on cold‑water corals, tropical reefs and Arctic ecosystems, with pteropods already showing shell damage that threatens marine food webs and food security.
• Two boundaries remain in the safe zone—global aerosol loading and the ozone layer—demonstrating that coordinated policies can deliver system‑level improvements.
• PIK scientists warn that crossing boundaries raises the chance of irreversible Earth‑system tipping points, yet emphasize that timely action can still reverse harmful trends.