Quantifying the carbon budget cost of overlooked landfill methane in sub-Saharan Africa

Abstract Landfill methane from sub-Saharan Africa is a rapidly growing but systematically overlooked contributor to global warming. Here, we model CH₄ emissions across 44 sub-Saharan African countries (2000–2100) under three waste disposal scenarios and conduct a systematic audit of waste-sector commitments in their nationally determined contributions. Cumulative emissions are equivalent to 1.1–4.5% of the remaining 1.5°C carbon budget by end of century, yet only 5 of 44 countries include an explicit methane target for waste, and none of the 10 largest emitters, which account for 71% of regional landfill CH₄, have such a target. Fourteen countries with zero waste-sector pledges represent 39% of modelled emissions. Stated investments totaling USD 10.5 billion are predominantly conditional on undelivered financing and technologically misaligned with immediate mitigation needs. We identify a development paradox: improving waste collection without building disposal alternatives, a trajectory several NDCs already commit to, brings methane likely already emitted by informal dumps into the scope of formal measurement, without necessarily reducing it.