This review paper applies a critical geographic perspective to analysis of planning ambition and prospect. Its point of departure is that planning, an applied spatial science, has lacked consistent review from critical geography in recent decades. The consequences of this drift for planning conception and practice are considered, focusing on the influential construct, the compact city. The review finds evidence of serious epistemological and methodological flaws in planning thought and ambition; failings that were earlier identified and analysed in the break with positivism in geographical sciences. The consequences of these limitations for planning thought and practice are considered. Broadly they undermine the ability of the compact city ideal to address what is arguably the most critical threat facing humanity, climate change. Specifically, the proposition that urban density has straightforward influences on human behaviour, including resource use, is without scientific foundation. Planning has a critically important part to play in climate response: securing the resilience and well-being of an increasingly urbanised human species. Urban compaction may not achieve these ends.