Indrianto, right, and Suratman of Yayasan Ekosistem Lestari (YEL) measure the depth of the peat at the healthy part of Tripa peat swamp forest in Nagan Raya, Aceh province, Indonesia. Photo by Dita Alangkara/CIFOR-ICRAF

Initiatives under REDD+ (“reducing emissions from deforestation and forest degradation and forest conservation, sustainable management of forests and enhancement of forest carbon stocks”) have been one of the primary hopes for halting tropical forest loss and fighting greenhouse gas emissions since the 2007 Bali Climate Change Conference.

However, REDD+ has also been controversial, often seen as an effort by the Global North to apply a remote fix to climate change, far from where the problem originated. Furthermore, many private forest carbon-offset initiatives have been shown to produce much “hot air”, that is, pretending under erratic baselines to halt forest loss in places where deforestation threats were nil or negligible to start with, and they would thus make little real difference.

So, if by now, a couple of decades after REDD+’s start, we took stock of all quantitative research published in the scientific literature, to what extent would the framework come out as having produced tangible results for the environment as for local livelihoods?

This is the question being answered in a new paper produced in the realm of the Center for International Forestry Research and World Agroforestry (CIFOR-ICRAF)’s Global Comparative Study on REDD+ and published in the Nature-Springer journal Communications Earth & Environment. This meta-study identified 32 quantitative studies using “rigorous” statistical methods, meaning they assess counterfactual baselines (‘What would likely have happened without the REDD+ intervention?’) using observations from comparable control sites.

As authors, we used 26 forest-related and 12 socioeconomic REDD+ quantitative effects from case studies in total. Not a lot, it might seem, for a decade and a half of REDD+ action. But, as in many other environmental fields, the initiative’s quantitative impact evaluation has lagged. Thus, compared to forest size, we realized that REDD+ action was strongest in the Andes, Indonesia, and East Africa, while research on REDD+ impacts, in turn, focused disproportionally on Latin America.

In aggregate, we found modestly sized yet statistically significant REDD+ impacts on forest conservation for private (NGO or commercial) and public programmes alike—but with substantial variations. A few of these studies indicate that when REDD+ payments stopped, deforestation typically picked up again, but without undoing temporary conservation gains made while the framework lasted.

The environmental results, while perhaps not uniformly impressive, are notably better than what might have been anticipated based on previous studies of private-sector carbon markets. A key reason for this is the broader range of REDD+ actions in the study, encompassing private-sector initiatives and efforts by NGOs and government PES (Payment for Ecosystem Services) programs. This mix offered us a more balanced perspective, rather than being dominated by actors sometimes referred to as ‘carbon cowboys.’

We have noticed that a mixed sample is also crucial to understanding the large variety of forest conservation outcomes. In particular, the programs implemented by NGOs with a solid scientific foundation often applied state-of-the-art REDD+ designs, achieving excellent outcomes. These helped us establish these cases, which serve as proof that well-designed REDD+ interventions can be successful in tropical contexts.

Conversely, projects in remote ‘high-and-far’ areas—those without roads and limited market access—tended to start with low deforestation pressures. As a result, their evaluated REDD+ impacts were lower, as making a positive difference proved more challenging in the absence of significant threats. Additionally, the effectiveness of the scheme’s efforts could be enhanced by focusing on strategic subregions, communities, or landowners, allowing them preferential access to enrollment, which, in turn, would likely increase the intervention’s forest conservation impact.

However, some under-performance in REDD+ outcomes was not solely due to location or design shortcomings. For many REDD+ projects, financial flows from carbon markets were more unpredictable than initially anticipated. Lacking a clear financial horizon, these initiatives hesitated to enter long-term commitments with landowners and local communities. Thus much, it arguably stayed in piecemeal or placeholder actions, trying out tentatively different actions without sufficient long-term strategy. As a result, REDD+ served a role in climate change mitigation similar to that of integrated conservation and development projects in biodiversity conservation—an umbrella concept for a highly diverse set of actions.

As for the local welfare impacts of REDD+ (on incomes, consumption, assets, etc.), these were smaller than the environmental effects or even nil. Average positive effects were usually larger for local household incomes and expenditures than for local people’s subjective well-being, reflecting frequent disappointment vis-à-vis the high initial expectations REDD+ had locally raised. Also, here, innovative design mattered. Differentiating REDD+ payments across beneficiaries (e.g., with respect to their variable opportunity costs of conservation) rather than paying uniform rates would boost socioeconomic impacts, including better addressing local equity issues.

When we compared these impacts to those from other conservation actions, such as protected areas or certification, REDD+’s environmental impact performance was average: neither better nor worse than the norm. Still, the heterogeneous impacts seem important as REDD+ interventions are upscaled to jurisdictional levels. If implementers at multiple scales can learn the right lessons from first-generational REDD+—including more targeted efforts in critical areas, improved contracts, a clearer long-term strategy, and greater market reliability—future interventions could achieve higher impacts.

The past two decades of REDD+ offer a nuanced but valuable learning experience. While it hasn’t delivered the sweeping results once hoped for, it has made notable contributions to forest conservation, particularly in regions where scientifically sound, well-designed projects were implemented. These early efforts provide critical lessons as REDD+ scales up: smarter targeting, stronger financial stability, and long-term commitments to both environmental and socioeconomic outcomes. With these improvements, future REDD+ initiatives have the potential to become a more powerful tool in the fight against deforestation and a model for sustainable, equitable climate action.