Into the Woods

Say you wanted to immerse yourself in a lush tropical forest to observe the impacts of climate change. You probably wouldn’t pack your bags and head north of sixty, but that’s exactly what Tropical Arctic invites readers to do. The result of an innovative science-art partnership, this book takes us to the remote and rugged landscapes of East Greenland and makes a case for slowing down, asking questions, and listening deeply to those who approach problems from different perspectives. In setting an example for interdisciplinary cooperation, two paleobotanists, Jennifer C. McElwain and Ian J. Glasspool, and a scientific illustrator, Marlene Hill Donnelly, breathe life into the long-lost forests of the world’s largest island.

Tropical Arctic looks back about 200 million years, to the end of the Triassic and the beginning of the Jurassic periods, a time of dramatic global warming that spurred “the third greatest animal extinction event in Earth history” and saw 85 percent of Greenland’s flora go extinct. To visually reassemble those ancient landscapes through fossilized material, the team had to determine vegetation types and abundances, along with how the plants existed in relation to one another and their surroundings. They achieved their results using paleobotany, modern ecology, geology, statistical analyses, modelling and sculpting, engineering experiments, and comparisons with living analogues.

Eons ago, East Greenland was home to lush plant communities that included large conifers, ginkgos, cycads, horsetails, vines, and ferns. But as the supercontinent Pangaea split apart, volcanic activity pumped greenhouse gases and toxic sulphur dioxide into the atmosphere. With skyrocketing concentrations of those gases, temperatures increased and the region’s greenery responded. Plants that could be considered “the weeds of their time” flourished due to their ability to survive in a wide range of conditions. The rocks from the beginning of the Jurassic period — found in the so‑called Disaster Bed — contain fossilized horsetails and evidence of a “fern spike,” a sudden colonization that swiftly filled the void created by the disappearance of other species.

Heat-tolerant varieties thrived in the warming conditions. Plants with narrow leaves lose heat more efficiently, so they had a leg up on their broadleaf counterparts. The advantage came with baggage, however: narrower leaves are more flammable. The combination of this characteristic, an increasingly dry landscape, and ever more intense storms powered by “a warmer and wetter troposphere” proved the perfect recipe for fires that hindered reforestation. The geological transition also favoured plants with relatively slow rates of photosynthesis; this shift altered the way the entire ecosystem functioned, including how organic material decayed and the resulting nutrients available for both plants and animals.

Greenhouse gas levels eventually dropped, and forests did return to East Greenland. Some species that were present in the Triassic reappeared, which indicates that they had found refuge in cooler environments until the region returned to more suitable conditions. New arrivals also appeared, but this took time. The recovery after the extinction event transpired over the equivalent of 2,500 human generations, a breathtaking figure that emphasizes the far temporal reach of climate catastrophe. Like manoeuvring a big vessel, a change in course in nature comes with a time lag.

Although the Triassic-Jurassic boundary is often represented with a single line on the geologic time scale, the transformations explored by McElwain, Donnelly, and Glasspool occurred over the course of about ten million years. Their innovative illustration of those protracted events advances our understanding of how landscapes might respond to what’s unfolding today. Ecosystems can and will adapt, but the migration of plants occurs at a generational scale, since they can’t travel like animals. Rapid environmental change may outpace the ability of certain populations to shift their ranges, and human activities can further block their migration to safe havens.

In Canada, some cold-climate species may run out of places to go, particularly when survival means migrating toward the North Pole or to higher elevations. Although present-day change is of a lesser magnitude, it is occurring at a “ferocious pace”— faster than that observed at the Triassic-Jurassic boundary. Yet Tropical Arctic reminds us that we can still act to reduce emissions and prevent the collapse of entire ecosystems.

Ours is a vast country with diverse environments that are foundations for cultures, livelihoods, and health. Although adaptation is possible, our landscape will not “look and function the same as it did before.” We need to ask ourselves what differences in the workings of our biosphere we are prepared to accept. The answers to such questions will likely be as varied as the scenery that surrounds us.