This seminal report explores critical components of the global climate between 2011 and 2020. Taking a longer-term perspective than annual reports, the Decadal Report transcends interannual variability, highlighting, for example, how each decade since the 1990s has been warmer than the previous one. It shows without a doubt that greenhouse gas concentrations have increased in the atmosphere, thereby contributing to record levels of warming of the land and ocean, the melting of ice sheets and glaciers, rising sea levels, and ocean acidification. As emissions rise and the climate changes, extreme weather and climate events are worsening. The decadal approach is unique in that it allows time for the scientific community to analyse the mechanisms behind extreme conditions and their likelihood of occurring in the pre-industrial era. For the very first time, this report demonstrates concrete connections between extreme events and development. Working in interdisciplinary collaboration with United Nations agencies and national statistics offices, select case studies demonstrate how extreme events across the decade have impeded progress toward the Sustainable Development Goals (SDGs). As the world continues to be off-track in reaching the SDGs, continued collaboration in addressing data challenges and socio-economic impact analyses is of ever-increasing importance.