An overview of the ‘Limits to Growth’ debate is provided, from Malthus to Planetary Boundaries and the Planetary Health Commission. I argue that a combination of vested interests, inequalities, and cognitive impediments disguise the seriousness of our collective proximity to limits. Cognitive factors include an increasingly urbanized population heavily in denial through declining exposure to nature, incompletely substituted by the rise of simulated, digital and filmed reality. Following prominence in the 1960s and early 1970s, fears of Limits to Growth diminished as the oil price declined and as the Green Revolution expanded agricultural productivity. While public health catastrophes have occurred which can be conceptualised as arising from the exceedance of local boundaries, including that of tolerance (e.g. the 1994 Rwandan genocide), these have mostly been considered temporary aberrations, of limited significance. Another example is the devastating Syrian civil war. However, rather than an outlier, this conflict can be analysed as an example of interacting eco-social causes, related to aspects of limits to growth, including climate change and aquifer depletion. To view the ‘root causes’ of the Syrian tragedy as overwhelmingly or even exclusively social, leaves civilization vulnerable to many additional disasters, including in the Sahel, elsewhere in the Middle East, and perhaps, within decades, globally. An aspect of the Limits to Growth debate that was briefly prominent was ‘peak oil’. Fear of this has fallen with the oil price. But this does not mean that Limits to Growth are fanciful or will apply only in the far future, even if (which seems unlikely) the oil price remains low. The proximity of dangerous climate change is the starkest example of an imminent environmental limit; other examples include declining reserves of phosphorus and rare elements. Crucially, human responses have the capacity to accelerate or delay the consequences of these limits. Greater understanding of these issues is vital for enduring population health, globally.