Ten New Insights in Climate Science 2025

This paper presents ten recent advances in climate change research with high policy relevance, spanning Earth system processes, climate impacts, and mitigation action. The record-warm years of 2023–2024 are explained by a combination of long-term greenhouse gas forcing, changes in aerosol loading, internal variability, and feedback processes leading to an elevated Earth energy imbalance — dynamics consistent with a continued acceleration of global warming. Northern land carbon sinks and permafrost regions are showing signs of strain, and biodiversity loss is increasingly understood to reinforce climate change through destabilising feedbacks. These Earth system stresses amplify cascading impacts — including accelerating groundwater depletion, a climate-driven surge in global dengue incidence, and growing labour productivity and income losses from heat stress — that interact with and exacerbate one another across systems. On mitigation, the synthesis finds that national plans fall significantly short of what is needed, that systemic integrity flaws afflict carbon credit markets, and that carefully designed policy mixes outperform stand-alone instruments in achieving emissions reductions. The authors conclude that surpassing the 1.5°C threshold is practically inevitable without massive cuts in greenhouse gas emissions, underscoring the urgency of ambitious mitigation action and significantly upscaled adaptation efforts.