Swamps and marshes once covered vast stretches of the North American landscape. The destruction of these habitats, long seen as wastelands that harbored deadly disease, accelerated in the twentieth century. Today, the majority of the original wetlands in the US have vanished, transformed into farm fields or buried under city streets. In The Marsh Builders, Sharon Levy delves into the intertwined histories of wetlands loss and water pollution. The book's springboard is the tale of a years-long citizen uprising in Humboldt County, California, which led to the creation of one of the first U.S. wetlands designed to treat city sewage. The book explores the global roots of this local story: the cholera epidemics that plagued nineteenth-century Europe; the researchers who invented modern sewage treatment after bumbling across the insight that microbes break down pollutants in water; the discovery that wetlands act as efficient filters for the pollutants unleashed by modern humanity. More than forty years after the passage of the Clean Water Act launched a nation-wide effort to rescue lakes, rivers and estuaries fouled with human and industrial waste, the need for revived wetlands is more urgent than ever. Waters from Lake Erie and Chesapeake Bay to China's Lake Taihu are tainted with an overload of nutrients carried in runoff from farms and cities, creating underwater dead zones and triggering algal blooms that release toxins into drinking water sources used by millions of people. As the planet warms, scientists are beginning to design wetlands that can shield coastal cities from rising seas. Revived wetlands hold great promise for healing the world's waters.

Until about 13,000 years ago, Europe and North America were home to a menagerie of massive mammals. Mammoths, camels, and lions walked the ground that has become our cities and streets. Then, just as the first humans reached the Americas, these Ice Age giants vanished forever. In Once and Future Giants, science writer Sharon Levy digs through the evidence surrounding Pleistocene large animal ("megafauna") extinction events worldwide, showing that understanding this history-and our part in it-is crucial for protecting the elephants, polar bears, and other great creatures at risk today. These surviving relatives of the Ice Age beasts now face an intensified replay of that great die-off, as our species usurps the planet's last wild places while driving a warming trend more extreme than any in mammalian history. Inspired by a passion for the lost Pleistocene giants, some scientists advocate bringing wolves back to Scotland, and elephants to America's Great Plains as stand-ins for their extinct native brethren. By reintroducing big browsers and carnivores to colder climes, they argue, we could rescue some of the planet's most endangered animals while restoring healthy prairie ecosystems. Critics, including biologists enmeshed in the struggle to restore native species see the proposal as a dangerous distraction from more realistic and legitimate conservation efforts. Deftly navigating competing theories and emerging evidence, Once and Future Giants examines the extent of human influence on megafauna extinctions past and present, and explores innovative conservation efforts around the globe. The key to modern-day conservation, Levy suggests, may lie fossilized right under our feet.

Until about 13,000 years ago, North America was home to a menagerie of massive mammals. Mammoths, camels, and lions walked the ground that has become Wilshire Boulevard in Los Angeles and foraged on the marsh land now buried beneath Chicago's streets. Then, just as the first humans reached the Americas, these Ice Age giants vanished forever. In Once and Future Giants, science writer Sharon Levy digs through the evidence surrounding Pleistocene large animal ("megafauna") extinction events worldwide, showing that understanding this history-and our part in it-is crucial for protecting the elephants, polar bears, and other great creatures at risk today. These surviving relatives of the Ice Age beasts now face an intensified replay of that great die-off, as our species usurps the planet's last wild places while driving a warming trend more extreme than any in mammalian history. Inspired by a passion for the lost Pleistocene giants, some scientists advocate bringing elephants and cheetahs to the Great Plains as stand-ins for their extinct native brethren. By reintroducing big browsers and carnivores to North America, they argue, we could rescue some of the planet's most endangered animals while restoring healthy prairie ecosystems. Critics, including biologists enmeshed in the struggle to restore native species like the gray wolf and the bison, see the proposal as a dangerous distraction from more realistic and legitimate conservation efforts. Deftly navigating competing theories and emerging evidence, Once and Future Giants examines the extent of human influence on megafauna extinctions past and present, and explores innovative conservation efforts around the globe. The key to modern-day conservation, Levy suggests, may lie fossilized right under our feet.