Tropical Arctic asks us to imagine the Arctic as a lush, green paradise (think Miami) through the story of an expedition to Greenland and the subsequent analysis of the fossils collected there by a team including an artist, botanist, and paleobotanist. The expedition team was specifically interested in a mass extinction event that occurred during a period of catastrophic climate change 200 million years ago between the Triassic and Jurassic periods. The team targeted particular fossil beds to help them find the answers they were looking for. They collected more than a metric ton of fossils and used the data to put together a picture of what the ancient Arctic ecosystem looked like by determining which plants were dominant and which were rare both before and after the mass extinction. They then used the fossils to create three-dimensional models to increase their understanding of the plant characteristics. This provided insight into which plants were resilient in the face of change and which characteristics might have contributed to that resilience. The team coupled this evidence with laboratory evidence on extant plants that measured their response to conditions similar to ancient Earth’s.
What was a dense forest canopy in the Triassic transitioned to lower-growing plants that had to survive harsh atmospheric conditions in addition to frequent fire in the early Jurassic. When conditions stabilized, those plants able to survive could thrive. The team hypothesized that the slow rate of change of Earth’s conditions contributed to the plants’ ability to migrate, essentially germinating where conditions were favorable. Certain species were better adapted for conditions on one side of the boundary. The book ends with lessons for the future, pinpointing the magnitude of temperature change associated with a reduction in biodiversity and loss of species and what it might mean for Earth’s future.
While the photographs and illustrations are beautiful, I found the story hard to follow. At the end of the book, I wished some of the information presented in Chapter 4 had been presented earlier. I was less motivated to learn about the expedition and all of the fossils collected because I didn’t know the story of the conditions on Earth that led to and followed the mass extinction. Had that context come first, it would have provided framing for the expedition, sparking curiosity about what the team found. I found myself wanting a map or a timeline to help me track Earth’s history both spatially and temporally.
It may be beyond the scope of this book, but I was left wondering about the conditions in the Arctic that allowed all that plant life to grow in the first place. How does the 40,000-year cyclical change in the Earth’s tilt play into the story of energy and matter in the Arctic? Does that explain why it was lush there once but cold and icy there now? And how will the anthropogenic changes we have made to Earth’s system interact with that natural cycle?
Today, many high school biology teachers are tasked with integrating Earth and space science standards into their curricula. Using historical events that caused changes to Earth’s system as phenomena can help students understand the flow of energy and matter and provide a context for understanding why the mechanisms of photosynthesis and cellular respiration are so important. Tropical Arctic is a beautiful text and illuminates a part of Earth’s history that I knew little about. On its own, it is missing necessary pieces to spark the interest of someone who lacks expertise in the field, but it would be a worthwhile complement to other texts on the topic.