When the ice is gone What a Greenland ice core reveals about Earth's tumultuous history and perilous future

Bierman, a geology professor at the University of Vermont, debuts with a granular account of studying Greenland ice cores. He recounts how in 2019, he joined an international team of scientists who stumbled upon long-neglected cores extracted from the Greenland ice sheet in the 1960s. Using them to reconstruct climatological history, the team discovered that Greenland's ice sheet had melted at some point in the last million years, when atmospheric carbon dioxide levels were significantly lower than they are today. The implication is that the ice sheet is more fragile than previously believed, Bierman argues, warning that if it melts again, it could "put a half-million square miles of land underwater and displace several hundred million people." Bierman presents an accessible discussion of the scientific methods used to date samples (to determine "the ages of boulders left behind by melting glacial ice... measure the concentration of isotopes in a sample and divide by the production rate of each isotope"). Unfortunately, extensive background on the logistical difficulties of maintaining the tunnel and heating systems at Camp Century, the northern Greenland U.S. Army outpost where the cores were collected, distracts from the book's focus on climate change. The result is an intermittently stimulating glimpse into the workings of climate science. Photos. (Aug.)

A potent examination of how melting glaciers and rising ocean levels are already at crisis levels. Except for the conclusion, Bierman, a professor of environmental science at the University of Vermont, has written not another global warming polemic but rather a compelling introduction to Greenland, glaciers, and how scientists drill down through ice to reveal the past. Greenland is the world's largest island; 80% is covered by glaciers, so it's sparsely inhabited, which only came to world attention during World War II and the Cold War. Aware that it was closer to the Soviet Union than Canada is, the U.S. War Department took an interest. Beginning in 1951, it built several bases in the far north. Mostly used for intelligence gathering and weather reporting, they also supported major research to understand the cryosphere, "the frozen portion of Earth." Happy to accept military dollars, scientists undertook the difficult, six-year engineering feat of drilling down through a glacier to bring up a mile-long core of ice and then dirt that revealed Greenland's history and made breakthrough discoveries about snow and ice mechanics, glaciers, and climate change. Having accomplished their purpose, the bases were abandoned by 1966, leaving behind immense deposits of frozen sewage, diesel oil, drilling chemicals, and radioactivity. Bierman delivers an expert account of the 50 years of research that followed in laboratories around the world; examining the core, scientists learned that within the last million years, the ice beneath the camps had melted without human involvement, and tundra plants had grown across Greenland. Having hinted at bad news, Bierman provides it in the final chapter, warning that the rising temperature is melting Greenland's ice, which holds enough water to raise sea levels by 24 feet. At the same time, the warming ocean and atmosphere are producing the deranged weather and violent storms already in progress. Frightening yet excellent popular science. Copyright (c) Kirkus Reviews, used with permission.