New book’s globetrotting tour of boreal forests establishes their value to life on Earth

“The Treeline: The Last Forest and the Future of Life on Earth”

By Ben Rawlence. St. Martin’s Press, 2022. 307 pages. $29.99.

The boreal forest, that ring of trees that circles the globe at high latitudes, is the largest living system after the ocean; it’s also the “lungs” of the planet and thus key to our planet’s health. Ben Rawlence, who lives in Wales and whose last book was about a refugee camp in Africa, has brought his concerns about human rights to the disastrous effects of climate change. From 2018 to 2021 he traveled around the northern forests — to Norway, Russia, Alaska, Canada and Greenland — to meet with residents and scientists and to learn for himself what’s been happening with the farthest-north trees and life associated with them.

How interesting can the treeline be? Incredibly interesting, it turns out, when the subject is in the hands of such a skilled researcher and writer. A book about trees can, we discover, be a page-turner. Part travel adventure, part deep dive into emerging science, part reflection on our history on Earth, part philosophical questioning about the fate of the Earth — ”The Treeline” is a lively and beautifully written weaving of fascinating topics.

Organizationally, the book circles the globe, with each chapter focused on not just a different forest but the tree species most significant for that forest. A map at the beginning, looking down on the North Pole, shows the forests, their northern reach, and the major communities that the author visited.

Rawlence begins in his neighboring Scotland, considered to be the limit of the Arctic treeline in Europe, although most of its trees were cut down centuries ago. Forest succession after the last ice age led to the Scots pine once covering about 80% of the land. Today, “rewilding” efforts are aimed at restoring some of that great wood, but global warming projections suggest that the United Kingdom’s climate will soon be too inhospitable for the pines.

In the next chapter, featuring Norway and the downy or European white birch, Rawlence visits the Sami reindeer herders in the far north. Here and elsewhere, the author makes very clear that forest health is directly related to human rights and the abilities of Indigenous peoples to maintain their cultural ties and livelihoods. Warmer and wetter weather has led Norway’s birch to “race” over the tundra, reducing the habitat required by reindeer and their herders.

In the Russia chapter, featuring the larch, Rawlence visits several treeline areas in the winter and meets with both scientists and Indigenous people. He journeys hundreds of miles in a tank-like vehicle with enormous tires to find the farthest-north trees in the world — spindly larches that grow in extreme cold over thick permafrost. Elsewhere, thawing permafrost causes rising water tables and the “drowning” of larches. He learns that scientists predict that at least 50% of Siberia’s forest is expected to convert to treeless steppe by the end of this century.

By the time Rawlence investigated Alaska’s treeline and the dominant spruce species, the world was deep into COVID-19 lockdowns. Unable to visit in person, he did an impressive job of studying maps, photos, and reports and speaking to researchers and residents. As he points out, “Alaska is the most studied area of the Arctic; the U.S. has the resources and scientific heft that other nations lack ... a frontier in our understanding of what is happening in geographic as well as scientific terms.” He details his Alaska conversations with Ken Tape, who’s studied how beavers have recently transformed the landscape; writer Seth Kantner, who grew up along the Kobuk River treeline; and Roman Dial, who’s studied changing vegetative dynamics, especially those of spruce, in the Arctic for more than 40 years. He also details the influences of fungal networks on forest health, the way warmer air affects photosynthesis, and the relationship between the evapotranspiration of Alaska’s spruce and rainfall in America’s Midwest.

In Canada, Rawlence spent time in Ontario with Diana Beresford-Kroger, “one of the foremost scholars of the boreal forest” — and, we learn, the model for a character in Richard Powers’ novel “The Overstory” — and then in and around Churchill, on Hudson Bay. Here we learn just how critical the northern forest is in regulating water, air, soil, climate and the productivity of the oceans. We also learn where the subtitle of the book, referencing “the last forest,” comes from. Beresford-Kroger believes that the Amazon and other tropical forests are “probably done for,” threatened as they are not just by intentional deforestation but by drying and fires. The boreal forest, by stretching over a wide temperature range, may have the best chance at adapting. In Canada, its key species is the balsam poplar, or cottonwood.

Rawlence’s final stop — in organization, not actual time — is Greenland. As the island’s ice cap melts, the land is becoming more habitable for trees, of which there are four native species, most significantly the rowan or mountain ash. Rawlence joins a group planting trees and discusses the emerging field of “strategic ecology,” which is based not on current climate conditions but guesses about the future. “Assisted migration” is another term related to helping species, including trees, move into places where they might survive a warmer world.

In the end, by showing how the boreal forest interacts with all life on Earth, Rawlence paints a grim picture of where we’re headed. He doesn’t offer false hope but speaks instead to a needed change in the way humans live. “Curiosity and noticing are the humble but radical prerequisites for a new relationship with the Earth. Systems change when there is a culture that demands it. The revolution begins with a walk in the woods.” Rawlence’s contributions to the cause include founding and directing Black Mountains College, a school in Wales dedicated to teaching skills for mitigating and adapting to climate change.