•Robust information on biodiversity patterns and trends is important for public policies for nature conservation and sustainable development.•Current Brazilian policy of cuts in science puts research programs and long term monitoring of biodiversity at risk.•Reduced spending will have long-term negative impacts on capacity building in science and technology.•Cuts will reduce Brazil's capability to predict, mitigate negative impacts of, and adapt to global environmental changes.•Cuts will result in less effective and efficient conservation strategies, threatening ecosystem services and human well-being, and in failure to reach the National Targets for Biodiversity 2011–2020. In the middle of a political and fiscal crisis, the Brazilian government is applying successive budget cuts, including in science funding. Recent cuts radically affect research programs on biodiversity that are crucial components for the design and monitoring of public policies for nature conservation and sustainable development. We analyze the consequences of such cuts on the Research Program on Biodiversity (PPBio), the largest biodiversity research network in Brazil (626 researchers, nine networks in all Brazilian biomes). Brazil holds a substantial part of the world's biodiversity and of tropical forests that play a significant role for regional and global climate stability. If underfunding is maintained, the dismantling of the Brazilian PPBio will have consequences that go beyond biodiversity knowledge itself but affect society as a whole. Brazil will likely fail to reach the National Targets for Biodiversity 2011–2020, and it will be difficult to fulfill the restoration target of the Brazilian NDC and to advance with the sustainable development goals.