<p>The infrastructure available to a nation for the management of its solid waste not only affects its population and environment, it plays a role in addressing global challenges of greenhouse gas emissions and ocean plastics. Several approaches attempt to address this purpose, but their adoption is dependent on available resources. While nations in the global south struggle with waste collection and rely heavily on open dumping, those in the global north invest in more advanced technologies to divert materials from disposal to recovery. To address cross-border waste concerns, a more in-depth understanding of the cost–benefit relationship of different strategies is required. Here we show that investment in advancing the waste infrastructure of the global south achieves a higher mitigation of greenhouse gas emissions and marine plastics than further upgrades in the global north. Basic collection is the essential step to reducing marine plastics, and a transition from open dumps and burning to controlled landfills does more to reduce methane and black carbon emissions than upgrading existing systems to advanced technologies. Our results demonstrate how targeted expenditures towards basic infrastructure components in those areas with the least investment are a more efficient use of global resources for mitigating climate change and reducing marine plastics.</p>