United in Science 2021: A Multi-organization High-level Compilation of the Latest Climate Science Information

This report provides a holistic assessment of recent climate science by synthesising data from several global partner organisations. The document examines atmospheric greenhouse gas concentrations, global emission budgets, and observed climate trends between 2017 and 2021. Utilising observational networks and climate modelling, the text establishes that human influence has unequivocally warmed the atmosphere, ocean, and land, leading to unprecedented changes across the biosphere. Key findings indicate that concentrations of major greenhouse gases reached new record highs in 2021, while global surface temperatures remained among the warmest on record. Furthermore, the analysis highlights an accelerating rise in sea levels and an increasing frequency of extreme weather events, such as devastating heatwaves and floods. The scope also encompasses future projections, revealing a significant gap between current national commitments and the emission reductions required to meet international temperature goals.