The dance of climate and biology

 kw: book reviews, nonfiction, biology, bioclimatology, climate change

The title of the book caught my eye: Hurricane Lizards and Plastic Squid: The Fraught and Fascinating Biology of Climate Change, by Thor Hanson. Midway through the book I found the stories behind the title. This illustrates the first. The three overlaid images show an anole lizard clinging to a branch in artificial winds of 35, 55, and 85 mph.

Anole lizards on Caribbean islands are frequently caught in gales or hurricanes. In the article that is the source of this image, "Lizards, toepads, and the ghost of hurricanes past", by Raymond P. Huey and Peter R. Grant, the authors report mapping the frequency of past hurricanes and comparing the forelimb strength and toepad size of anole lizards with each island's "hurricane index". They used the simple expedient of bringing a high-powered leaf blower to island after island, and measuring how much wind it took to blow a lizard off a branch it chose to cling to when the "wind" began blowing. Islands with more frequent hurricanes harbored stronger lizards with bigger toepads.

I'll leave it to you to check out the story of the lifestyle plasticity of certain species of squid. Such plasticity is one characteristic that helps some species thrive in spite of change, compared to less plastic species, which are more likely to go extinct. Perhaps bears and roaches really will outlive all of us.

Dr. Hanson spends little time discussing climate change as such; leaving that to others, he begins with the fact that climate warming is happening, and chronicles the various ways animals and plants are changing along with it. 

Some change by moving, either poleward or uphill. Census surveys of mountaintop species over many years reveal just how rapidly such changes can occur. The species that "liked" the crest of a mountain in cooler times find themselves with nowhere to go (unless they are birds), and die out, even as species that had been living at lower elevations move upward. I was quite interested by the description of just how rapidly some tree species can "move" by sending fruits and seeds on their way. Some can move many miles per generation, if they produce a fruit that is eaten by a mobile creature. Others are restricted to the distance a nut might be blown during its fall from the treetop. But the love some birds such as jays have for acorns means that oaks can be dispersed quite a distance, by acorns that birds hide but forget about (the trees are hoping for imperfect memories!).

Evolution is generally considered too slow to help creatures survive a warming as rapid as the one currently going on. That is probably true in many cases, but not all. The anoles shown above are actually evolving fast enough that some will survive a doubling or tripling of the number of category 5 hurricanes across their island. Initially, adaptation keeps some anoles alive through a season, but there is also the weeding-out of weaker-limbed individuals, so the next generation includes a larger proportion of stronger lizards. Random genetic drift ensures that a few will be extra-strong, as the occasional helpful mutations accumulate. This can go pretty fast in animals with a generation time of a year or two.

How far will climate change go? Dr. Hanson describes a "kitchen experiment" with carbon dioxide and a heat lamp, originally done a couple centuries ago in a brewery (where huge amounts of CO₂ are produced), that illustrates the heat-blanketing effect of the gas. It roughly confirms a calculation that I learned to do before I was in high school (I had smart parents and a couple of good mentors): it shows that greatly increasing CO₂ seems to top out the heating at 4°C. That may not end civilization, but it won't be pretty. It certainly won't "destroy the earth" or the biosphere, but it will make some big changes. So of course the author asks us, "What can we do?", answering, "As much as we can, in as many ways as we can." For me, that includes convincing Limousine Liberals to drop out of the jet set. A single cross-country or cross-ocean flight produces, for each person aboard, as much CO₂ as a few months of driving an SUV.

Meantime, I'm a homebody, married to a homebody. Out total miles driven for two cars is less than 12,000 miles yearly, while the average distance driven by most cars in the US tops 14,000 miles. It doesn't mean we are particularly virtuous, just boring. This book is anything but boring. It's a fun read, with many interesting stories.