Consider the geologic term "Anthropocene." It may not be familiar to you right now, but odds are it will work its way into general conversation in the near future. Just as Jurassic is known as the Age of Reptiles and Pleistocene as the Ice Age, Anthropocene denotes Age of Humanity, our current geological epoch, a time when human activity is significantly changing our planet and its climate.
This is a foundational concept of “Earth in Human Hands: Shaping Our Planet’s Future,” David Grinspoon’s sprawling but cohesive meditation on Earth’s long past; its volatile present, with human-activity-induced climate change; and some possible future scenarios. Basically: Here we are, here’s how we got here and where we go from here.
Grinspoon is an astrobiologist (Planetary Science Institute), which means he studies life on Earth and on other planets. Astrobiology is a big-tent discipline, encompassing fields like biology, astronomy, geology and atmospheric sciences. Grinspoon highlights the advantage of studying Earth within this vast context: The "planetary perspective allows us to step away from the noise of the immediate present, to see ourselves from a distance, in time-lapse."
With an erudite yet appealingly informal style that showcases his nimble mastery of this science, Grinspoon takes you on a deep-time tour through four types of Earth’s changes (aka catastrophes): random (like the great dust-inducing asteroid crash that wiped out the dinosaurs), biological (emerging of new species, dying off of others), inadvertent (unintended effects of industrialization) and intentional (doing something, or not, about those industrialization effects).
With such unpretentious panache (as well as a fearless inclination toward puns), it’s no surprise that Grinspoon is a frequent science commentator on TV and radio. He is also an award-winning author, perhaps best known for a previous general-interest science work, the 2003 "Lonely Planets: The Natural Philosophy of Alien Life."
A native of Greater Boston, Grinspoon comes by his scientific interests naturally. A close family friend was iconic astronomer/author/science popularizer Carl Sagan, who taught at Harvard with Grinspoon’s father (a professor of psychiatry), and whose tales of space exploration fueled young David’s interest in planets, climates and the possibility of extraterrestrial life. In our hyper-technical world, we need science communicators like Grinspoon (and Bill Nye and Neil deGrasse Tyson) who can translate their expertise into accessible explanations and interesting stories. All complex topics have interesting stories; it takes a particular talent to unlock them.
In "Earth in Human Hands," Grinspoon does not waste pages debating climate change ("it’s not my purpose here to convince the holdouts"), and his highlight list of climate change evidence is similar in scale and scariness to that of other scientists ("the retreat of glaciers, rising sea level, wholesale migrations of species to higher latitudes, and large-scale deviations in precipitation patterns and ocean chemistry").
Even so, this book is timely not just for the planet’s environment but for the current political one. President-elect Donald Trump has called climate change a "hoax," he has named Oklahoma Attorney General Scott Pruitt, a foe of environmental regulations, to head the EPA, and Speaker of the House Paul Ryan has stated that clean energy plans and regulations would be "disastrous for the American economy." Bob Walker, an adviser to president-elect Trump, has recommended that NASA should no longer engage in climate research. But, since its inception in 1958, some of the most significant discoveries about the Earth’s climate have come from NASA -- from its many committed scientists, from data about Earth from orbiting satellites and from revelatory data about other planets’ climates from explorer spacecraft.
As someone who rarely picks up a book about planets and stars, I was happily surprised to be eagerly turning pages to read more about how Earth’s essential blend of ever-moving tectonic plates and volcanic activity distinguishes it from its planetary neighbors. Or to dive deeper into the accounts of how two major, initially unrelated discoveries in the 1970s -- the aforementioned ancient asteroid impact, and the 1971 Mariner 9 space probe that yielded a trove of data on Mars dust storms — led to the 1980s theory of nuclear winter. The devastatingly bleak scenario is credited with inspiring the partial disarmament of nuclear weapons by both the U.S. and Russia near the end of the Cold War.
This is one of the great strengths of "Earth in Human Hands": Grinspoon’s ability to describe and explain momentous Earth and space events and discoveries, and then connect to their cultural and social influence; science as part of everyday life and our cultural history, not separate from it.
It’s all in the telling. You can present Earth’s history as a long timeline of epochs and catastrophes and rejuvenation, dotted with some bold-faced scientist names, or you can weave together the stories and discoveries, often filled with sweat and joy, behind these events. Grinspoon mentions early on that he doesn’t believe in the lone "great person" theories of science history; “Earth in Human Hands” is densely populated with remarkable scientists and scientific teams, many of whom Grinspoon has worked with.
“Earth in Human Hands” makes a convincing case that, for the last hundred years or so, and especially since the middle of the 20th century, "We have, unconsciously, been making a new planet."
This book has numerous illustrations and just two graphs, but they’re the right graphs. One, the "Keeling Curve," a sharply inclined line, shows carbon dioxide levels from 1958 through 2005. During that time, they rose by nearly 30 percent. As Grinspoon notes, “That’s not a tweak; it’s a jolt.”
The other is a two-part set of individual graphs, from a 2011 issue of “Philosophical Transactions of the Royal Society” whose theme was a question: “The Anthropocene: A New Epoch of Geological Time?” One set shows human activity (like water use or international tourism) and the other set shows Earth systems (like surface temperature or tropical forest loss), from 1750 to 2010. Across activities, there’s a very gradual increase until about 1950, when all lines, no matter the category, steeply rise.
This is known as the "Great Acceleration." It shows no sign of slowing down without, as Grinspoon posits, some intentional human intervention and cooperation. He marvels that we “suddenly find ourselves sort of running a planet … without knowing how it should be done." A reader who enjoys browsing vintage scientific publications, with their "expired forecasts about the human future," he avoids making predictions. But he does propose some potential scenarios, which have more hope than gloom.
As with many books of this size, there is some redundancy in later chapters, occasionally crossing that fine line between helpful summarization and circling back a little too often to previous points, and the sections on interstellar communication feel too long for their relation to the book’s main topics. But these are minor complaints about a book that makes a vital contribution to one of the most important concerns of our time.
As Grinspoon writes, “We do more than just inhabit the Earth.” That view may not be new, but its simple message, and this fine work, emphasize that, like it or not, we must acknowledge and expand into our roles as stewards of our distinctive, and increasingly fragile planet.
David Grinspoon will be at the Harvard Book Store to discuss his book on Friday, Dec. 9 at 7 p.m.