Adverse Climate: Addressing Inclusion and Diversity Issues in the IPCC's Sixth Assessment and beyond

In this essay, we reflect on what it means for the scientific community to collaborate effectively in global scientific assessments, drawing on our experience within the Intergovernmental Panel on Climate Change (IPCC) and with relevance beyond the IPCC to many other scientific collaborations. We amplify IPCC author voices through lived-experience narratives that reveal how systemic barriers limited participation of Global South authors, people of colour, non-native English speakers, early-career scientists, women, and those outside academia during the IPCC's Sixth Assessment Report (AR6), particularly in Working Group II. These experiences expose the "meritocracy myth" in academia, where privileged individuals claim recognition while ignoring structural advantages, thereby perpetuating power imbalances and limiting equity. We focus on overarching issues that perpetuate exclusion within global scientific assessment reports, some costs if these remain unaddressed, and key considerations toward more inclusive future collaborations. We stress that an effective collaborative culture requires moving beyond diversity metrics: the scientific community must actively dismantle colonial knowledge hierarchies that are silencing diverse perspectives and instead embody the very transformations that we call for in our reports. Alternative forms of knowledge are often only accepted when verified through reductionist, positivist methods of Western science, and are therefore downplayed. Unless these deeper dynamics—and the value systems that sustain them—are confronted and addressed, well-intentioned reforms risk sliding into tokenism, treating symptoms rather than causes. We cannot continue with business as usual, celebrating diversity statistics while power structures remain unchanged.