The severity of environmental threats, especially climate change, biodiversity loss and pollution, are well established, as is the urgent need for them to be addressed. These threats act both in isolation as well as synergistically to contribute to overall 'environmental breakdown'. Debate exists around the most optimal governance and policy approaches to address these threats and, to date, little quantitative evidence exists to compare the different approaches. Using a modified Bayesian belief network model to assess the probability of environmental threats, we compare and contrast a range of proposed policy solutions to a selection of contemporary environmental problems that have been identified as having the potential to contribute to, or indeed may lead to environmental breakdown. Through interrogation of the models, we conclude that policies that prioritise economic growth at the expense of nature would be largely ineffective, whereas a more integrated approach, adopting comprehensive 'Green New Deal' policies combined with nature-based solutions would be the most effective approaches to preventing 30