Hurricane Lizards and Plastic Squid How the Natural World is Adapting to Climate Change

If you had asked me last week how animals and plants will respond to climate change, I probably would have told you that they are expected to move towards the poles, shifting their home ranges as temperatures rise. This is indeed one possible response, but the challenges and opportunities for organisms are far more diverse and unpredictable. Biologist Thor Hanson has previously written much-praised books on feathers, seeds, and bees. Here, he gives a well-structured and terribly interesting whistle-stop tour of the nascent field of climate change biology and some of the fascinating research that is underway.

Part of what makes Hurricane Lizards and Plastic Squid a very readable book is its logical organisation. Hanson sets the stage with the history of our discovery that the world was not constant but subject to change, and the discovery of carbon dioxide. But the book revolves around the challenges that organisms face, their responses, and the results. All three hold diverse surprises. To flesh out this framework, each chapter discusses several examples of exciting research, glued together with autobiographical anecdotes.

As the climate changes, so does the timing of seasonal events (the study of which is known as phenology). When for instance plants flower earlier, pollinators might still be absent or in hibernation. Increasingly, species "find themselves in the right places at the wrong times" (p. 39). Rising temperatures can push animals to the edge of their comfort zone, and work on lizards shows they spend more time sheltering to avoid overheating, which is time not spent foraging. Work on starfish has shown that heat pulses can encourage disease outbreaks, contributing to marine epidemics. On land, forests in North America and Canada are suffering from one of the largest insect outbreaks in history, with bark beetles moving north almost unimpeded. Thousands of species are on the move, though rarely at the same speed or even in the same direction, making the situation so chaotic as to be unpredictable. Biologists have started talking of global weirding as whole ecosystems are now unravelling and rearranging themselves, challenging both the species remaining behind and the invaders trying to settle into new environments. Part of the reason that organisms move is that certain requirements in their habitat are no longer met and research on various mollusc species reveals how they struggle to build, maintain, and repair their shells as the oceans absorb carbon dioxide and acidify.

But all is not lost, "nature is not defenseless" (p. 82). Plants and animals can and do respond, and biologists often summarize it with the acronym MAD: Move, Adapt, or Die. Though, as Hanson goes on to show, that rather undersells it. Earlier chapters already discussed moving as a response, and populations can redistribute themselves surprisingly quickly. Even trees move, a story which has a fascinating deep-time component not mentioned here. However, there are limits to how far polewards or upslope you can go. Near the top of both you run out of habitat, and work on mountain top specialists amongst birds has demonstrated species winking out of existence. Other species, the plastic squid of the book's title, are incredibly flexible, whether in their behaviour or morphology. Humboldt squid in the Gulf of California seemingly disappeared in response to heat stress, until scientists realised they matured in half the normal time, staying much smaller as a result. There is also some delightful work described here on the titular hurricane lizards that documented an evolutionary response in Caribbean anole lizards in the wake of hurricanes, involving both long-term meteorological data and a leaf blower. Hanson's chapter on refugia is absolutely fascinating. There are places where stable microclimates allow plants and animals to hunker down and ride out the storm, with sites in Europe and North America still harbouring survivors from the last ice age.

As the book progresses, Hanson managed to draw me in further with ever more fascinating ideas and clever explanations. I was sold on his pitch for the final part of the book where he explores the results from the interplay of challenges and responses. He covers the "potentials and pitfalls of prognostication, how models are made, how surprises are certain, and how the clearest sign of what to expect may lie in what has already happened" (p. 151). He nimbly explains the concept and history of the Holdridge Life Zone System. This has become a staple of ecology textbooks that combines certain climate variables to predict vegetation and habitat conditions and has been ground-truthed and refined over the decades. But model predictions can mislead, and checking what actually happens on the ground can give surprising insights. The little auk is a bird species that lives near the North Pole and feeds at the edge of the ice shelf. It was predicted to follow the retreating ice northwards, but instead has turned to a new local food source: zooplankton shocked to death by freshwater pulses from melting glaciers. Joshua trees, meanwhile, are an evolutionary anachronism, "haunted and hampered by the past" (p. 185). They cannot spread northwards because our ancestors extirpated their seed disperser, the giant ground sloth. And in what seems to be applied lessons lifted straight from Felisa Smith's textbook Mammalian Paleoecology, Hanson discusses what the past can reveal, because "while the drivers of this episode may be different [...] climate change is nothing new" (p. 187). He delves (literally) into the value of packrat middens and discusses the relevance of the Paleocene-Eocene Thermal Maximum as the best past analogue for what is in store for us.

Given that this book is a whistle-stop tour of climate change biology, it is inevitable that some topics are not explored. Fortunately, other books pick up that slack, with e.g. Greenhouse Planet discussing what all that extra atmospheric carbon dioxide means for plant growth. And Hanson only dips his toes into the impact of climate change on humans by referencing a smidge of environmental history and pointing out that our responses today often mirror those of animals and plants.

It has been a few years since I reviewed Hanson's last book and I am embarrassed to admit that I forgot just how captivating and accessible his writing is. An enthusiastic science communicator, he seems to have the enviable ability to find researchers working on underreported topics and get them to spill their beans. Hanson effortlessly combines accessible reporting with insights into fundamental biological and climatological processes. To this, he adds a spoonful of endearing personal anecdotes to make for a delightfully smooth introduction to climate change biology.