Welcome to Climate Briefs, the summer series for This Climate Business. I ask a simple question, our experts give a succinct answer. Because in the end everyone likes a tight brief, right?

This week I ask Alex Johnston of Oxfam NZ to explain climate finance – the arcane world of country-by-country commitments to fund the transition to a low-carbon world. Who sets these sums, who pays and who ensures that promises are fulfilled?