The release of the Intergovernmental Panel on Climate Change (IPCC) Assessment Report Six (AR6) Working Group I (WG1) report in August 2021 brought to completion what is arguably the most thorough and scrutinised assessment of climate knowledge needed to steer the planet away from dangerous and irreversible climate change.1 The AR6 WG1 report builds on the Assessment Report Five WG1 report published in 2013, as well as on three special reports commissioned during the AR6 cycle: the Special Report on Global Warming of 1.5 °C (SR1.5), the Special Report on the Ocean and Cryosphere in a Changing Climate, and the Special Report on Climate Change and Land. The AR6 WG1 report as such does not come up with fundamentally new insights into the planet’s coupled carbon-climate systems, but through its assessment of ~14 000 publications and response to 78 000 review comments, it provides an unprecedented level of confidence to earlier findings. What it reveals is that there have been critical methodological advances in both observation and modelling that have enabled improved levels of confidence2 and opened doors for new science on global and regional climate-carbon challenges. These improved confidence levels are necessary to support the deeply transformative global, and South African, decision-making towards net zero CO2 emissions by 2050 in support of restricting global warming to below 1.5 °C relative to the pre-industrial temperatures.3,4 Our Commentary focuses on the assessment of the global climate-carbon system with implications for adaptation and mitigation action in southern Africa, and we provide a view of new research opportunities for regional climate and sustainability science.