When it comes to counteracting humans' negative influence on Earth, prolific essayist Diane Ackerman remains optimistic. In The Human Age, she focuses on the dire need to address climate change. She is “enormously hopeful” because the problem's cause—human ingenuity—is also its solution. “Our mistakes are legion, but our talent is immeasurable,” she writes.

Ackerman provides many examples of human-induced climate problems. In discussing the effects of human activity on reefs, she notes that the last time reef death occurred was sixty-five million years ago—that is, when an asteroid wiped dinosaurs off the planet. She profiles the Yup'ik tribe in Alaska, whose members, due to melting permafrost, have become climate change refugees. And she examines the case of Tuvalu, a small island nation that has been forced to evacuate its citizens to New Zealand due to a rising Pacific Ocean.

Ackerman takes us on several tours of her Hudson Valley garden in order to drive the point home that there is no corner of our planet—from our own backyard garden to the depths of the oceans—that has not been altered, either subtly or glaringly, by human hands. This point, combined with her argument for the potential of human ingenuity to help bring about climate improvement, leads her to the book's main argument: that the human species can be held as ethically duty-bound to try and offset climate change. She applauds, for example, the endeavors of the tiny island nation of the Maldives to aim for carbon neutrality by 2020. For her, programs such as the Maldives' are not just commendable peripheral exceptions but well-instituted models that can and should be replicated by other nations. The resulting global impact, if others do indeed follow, would be profound.