Summary
Palm oil is the most widely produced and consumed vegetable oil worldwide, but its production is associated with deforestation and other environmental and social problems. Roundtable on Sustainable Palm Oil (RSPO) is the only internationally-recognized voluntary certification standard aimed at mitigating such problems. Many studies examine RSPO’s effects on particular outcomes in specific contexts, but a consolidated global assessment is lacking. Here, we systematically review the literature and identify 53 original studies covering RSPO effects in various countries of Asia, Africa, and Latin America. Where data availability permits, we also conduct meta-analysis. Results reveal that RSPO can lead to environmental improvements, such as reduced peatland use and greenhouse gas emissions, but these effects are context-dependent and not consistently achieved. RSPO reduces deforestation within certified concessions, but this is largely offset by leakage to non-certified land, such that the overall effect on deforestation is insignificant. RSPO contributes to improved oil palm yields, especially for large-scale producers, and often also to higher profits and incomes. Yet, RSPO seems to exacerbate asymmetric power structures. Certification of independent smallholders remains limited due to technical and institutional constraints. While RSPO has certain positive effects in specific situations, further development of the standard and other policies are needed to make palm oil production more sustainable. Another important finding is that the methodological approaches of the original studies vary considerably. Rigorous impact studies consistently show smaller effects than less-rigorous ones, suggesting that uncontrolled confounding factors may lead to exaggerated reports about RSPO benefits.