Frontiers 2025: The Weight of Time – Facing a new age of challenges for people and ecosystems

This report scans emerging environmental risks and responses, drawing on UNEP’s foresight work and scientific reviews. It profiles four pressing issues: reactivation of microbes as the cryosphere thaws; removal of dams and other barriers to restore rivers; vulnerabilities of ageing populations to heat, pollution, and disasters; and remobilization of legacy pollutants during extreme floods. The report explains mechanisms, evidence, and trends, highlights policy options such as surveillance, barrier inventories, inclusive adaptation, and nature-based flood management, and stresses preservation of cryospheric microbial diversity for science and biotechnology. It is intended to inform anticipatory policy and risk management across regions and sectors.