Ben Rawlence is justifiably worried. His book was published before the latest report from the Intergovernmental Panel on Climate Change (February 2022), which reiterated the message that human-induced climate change is causing dangerous and widespread disruptions to the natural world. But unlike the usual focus on tropical forests or coral reefs, the focus of the author's concern is the rapidly changing boreal forest. Boreal denotes the Greek god of the north wind.

The boreal forest gets little international love; it is the poor cousin of tropical, temperate and montane forests. Even savannah ecosystems get more attention. Yet boreal forests cover vast areas, reportedly harbour one-third of all trees on Earth, and after the oceans are the largest ecosystem. With that size it is no wonder that boreal forests have been shown to play critical roles in planetary cycles such as water, oxygen, atmospheric circulation and polar winds.

Rawlence's focus is specifically on the treeline, by which he means the transition between an arboreal ecosystem and a treeless tundra. In some places this transition zone is just a few meters wide, in others it spans hundreds of kilometres. Whatever its width, this zone is highly dynamic as the climate changes, and in turn affects fire, permafrost melting, and other major ecological drivers. These rapid changes mean that, as the author points out, some places where trees could once sprout have become inhospitable for future generations of trees, whereas places that were once unsuitable are becoming viable habitats where those same tree species can now grow.

In a compelling and well-written set of chapters Ben Rawlence visits a circumpolar selection of boreal forest settings. He structures these visits around the six species of trees that together make up much of the boreal forest: Scots pine in Scotland, birch in Scandinavia, larch in Siberia, spruce in Alaska and, to a lesser extent, poplar in Canada and rowan in Greenland. What is remarkable for those of us less well acquainted with the boreal forests is that these largely comprise single species; for example, just larch comprises over one-third of the whole taiga. These six species essentially are the boreal (at least the tree part).

Each visit is a travelogue complete with local guide, scientists, a bit of adventure, and a short lesson on the focal trees and the fate of the boreal forest they comprise. The account entitled Chasing reindeer, set in Norway, is my favourite, with a set of interesting people and a compelling story about changes in the relationship between people, reindeer and birch.

The author is a journalist and has written about war and refugees in Africa, an experience that strongly colours the way he views the boreal world. He writes fluidly and well but his command of ecology is limited and he occasionally strays into places where a good technical edit would have been helpful. He is not overly concerned with citing sources and shows a tendency to be swayed by particular dimensions of his topic without a critical view of the results. Rawlence loves to travel and shares many stories about people, food and the nitty gritty of fieldwork. These inevitably shift attention away from the science and from the boreal forest itself and the changes it is undergoing. If this is fine with you then you will enjoy this book. But if you are looking for a book with depth and breadth about changes in the boreal or a sophisticated understanding of the underlying science, this will not be the volume for you.

Rawlence is very alarmed by what he learns and he conveys this well through phrases such as ‘the spirits of the tundra and the forest [are] shrieking their warnings’ (p. 74). Ultimately, he is a romantic experiencing and documenting the vast changes in the boreal, and writing with a poet's pen and a deeply worried heart. His is the perspective of a northern-hemisphere writer and a lover of trees. It is not the global perspective he claims, a fact that changes nothing for the diverse human cultures and the millions and millions of organisms struggling to make their lives and follow their evolutionary paths in the rapidly changing boreal forests.