In our fast-paced world, where almost any destination is a commercial flight away, it is easy to lose a sense of the incremental changes to our habitats. Aitken asks us to consider trees as the bell-weather of climate change. Her overview starts in the boreal forests of Canada, where warming temperatures have had a doubly negative effect on trees through the spread of insects, whose damage was previously kept in check by colder annual temperatures. In turn, these habitats have also witnessed the devastating impact of wildfires. Globally, the prospects are yet more chilling. In California alone, over 150 million trees have been lost in recent years due to consistent seasons of drought. The climate-induced effects on trees perhaps pales in comparison to the indiscriminate global destruction of forests by humans. Tropical forests have suffered in particular as the demand for meat and cheap palm oil used in processed foods has devastated vast swathes of the Amazonian and southeast Asian rainforests, now permanently lost to cattle ranches and monoculture plantations. Aitken notes throughout that the recently fashionable idea of planting trees is no magic wand. Planting trees globally cannot simply be a like-for-like replacement for the vast, intricately connected and unimaginably biodiverse ecosystems represented by the world’s forests. Instead we must focus on the absolute necessity of halting current rates of deforestation and finding sustainable ways of managing forest habitats, and the lives of communities that depend on them. Looking further, the future of humanity depends on the hugely complex, and seemingly insurmountable, task of remodeling our global energy, production and transportation networks. We must begin now.