Abstract
Equity is a cornerstone of international climate policy, yet operationalizing “fair” burden-sharing remains challenging. Here we present a comprehensive effort-sharing framework that systematically spans a broad spectrum of principles, rather than limiting analysis to a few discrete definitions, to allocate the remaining global mitigation burden. We integrate these diverse fairness criteria with varying regional mitigation rates and limits on negative emissions, thereby bridging the gap between committed and fair net-zero target years.