An international plan for sustainable development

International cooperation on climate and taxation remains inadequate to deliver decarbonisation, reduce poverty, and finance sustainable development at the required scale. We propose a Sustainable Union among willing countries, combining carbon pricing, new taxes on wealth, polluting fuels, financial transactions, and corporate income, with international revenue-sharing and conditional cooperation mechanisms. Most revenues would remain with participating governments for domestic spending, while a defined share would be pooled internationally. Specifically, participating countries would contribute 1% of gross national income (GNI) to a common pool redistributed in proportion to population, generating net transfers from richer to poorer countries. Meanwhile, the remainder of the revenue would increase domestic fiscal space by on average 2.2% of GNI. Although politically ambitious, such a framework might be credible, as governments are already advancing related forms of voluntary cooperation, and survey evidence indicates that it would be supported by majorities worldwide.