Walden Pond: a warning to us all (Image: Peter Dennen/Aurora Photos)

A hymn to citizen science, Walden Warming by Richard Primack seeks the reality of climate change in the effects that ordinary people have recorded

IN 2001, at the age of 52, Richard Primack packed the records of 21 years of research on tropical rainforests into a filing cabinet.

Despite a cool reception from his colleagues at Boston University, the professor of biology had decided to leave that research behind, and see what he could do to make the threat of climate change more tangible. He wanted to find evidence of warming that would be so “up close and personal” that people could not remain unconcerned by change that is too slow for most of us to feel.


Primack had a eureka moment early on, which explains why he called his book Walden Warming: Climate change comes to Thoreau’s woods. Henry David Thoreau was the 19th-century author of Walden, which gave an account of the time he spent living close to nature in a cabin near Walden Pond, Concord, Massachusetts. His writings of those “delicious” evenings when “the whole body is one sense, and imbibes delight through every pore” were to change the American psyche.

Primack was astonished to find that Thoreau also kept a detailed record of the flowering times of more than 300 plants around Walden, gathered over many years of walking for 4 hours a day. Primack was on his way, with a historical baseline from one of the US’s most revered authors and environmental pioneers.

The book tells the story of Primack’s struggle to replicate Thoreau and find changes in flowering times, but soon broadens into a hymn to citizen science. Primack finds many others who are not conventional scientists but keep careful records of myriad things, from the times that migratory birds arrive to the date butterflies emerge and ice melts on ponds. It is these extraordinary people who make the book a rich, rewarding read And there is also the inspiring message that anyone with a keen eye for nature can make a difference, with an afterword on how to become a citizen scientist.

There is the inspiring message that anyone with a keen eye for nature can make a difference

With many shoulders to stand on, signs of local climate change emerge. For example, for every degree Fahrenheit (0.56 °C) the temperature rises in Massachusetts, plants flower on average 1.7 days earlier – at least the lucky ones do.

Frighteningly, temperatures have risen around 4° Fahrenheit since Thoreau’s day, and many of the plants he saw have vanished. Analysis suggests plants that can change their flowering time survive, while less adaptable species don’t. The harsh message of climate change is “adapt, move or die”. For plants that can’t adapt or move their range to cooler climes, local extinction is likely. It is a message that may also apply to humans, if we don’t heed the advice Primack suggests we take from Thoreau: “live simply”.

Walden Warming: Climate change comes to Thoreau’s woods Richard Primack University of Chicago Press

This article appeared in print under the headline “Climate up close”