Ensuring that offsets and other internationally transferred mitigation outcomes contribute effectively to limiting global warming

International audienceEnsuring the environmental integrity of internationally transferred mitigation outcomes, whetherthrough offset arrangements, a market mechanism or non-market approaches, is a priority for theimplementation of Article 6 of the Paris Agreement. Any conventional transferred mitigationoutcome, such as an offset agreement, that involves exchanging greenhouse gases with differentlifetimes can increase global warming on some timescales. We show that a simple ‘do no harm’principle regarding the choice of metrics to use in such transactions can be used to guard againstthis, noting that it may also be applicable in other contexts such as voluntary and compliancecarbon markets. We also show that both approximate and exact ‘warming equivalent’ exchangesare possible, but present challenges of implementation in any conventional market.Warming-equivalent emissions may, however, be useful in formulating warming budgets in atwo-basket approach to mitigation and in reporting contributions to warming in the context of theglobal stocktake