The UNEP Year Book 2009 examines in six chapters new science and developments, and discusses the cumulative effects expected from degradation of ecosystems, the release of substances harmful to those ecosystems and to human health, the consequences of our changing climate, the continued human and economic loss resulting from disasters and conflicts, and the overexploitation of resources. It calls for an intensified sense of urgency for responsible governance in the face of approaching critical thresholds and tipping points.