Taxonomy term

The 2016 book, “Tipping Point for Planet Earth,” by paleoecologists Anthony D. Barnosky and Elizabeth A. Hadly, is a serious book on a serious topic, and a well-written, one-stop resource for anyone who wants to understand a host of looming problems. The book focuses on the alarming number of worrisome planetary trends now underway, mainly as a result of the convergence of population growth and human-induced global warming. Chapters cover people (population growth), “stuff” (increased purchases of material goods), storms, hunger, thirst (failing water supplies, clean or not), toxins, disease and war. These trends have merited serious attention from environmental scientists and deserve the same from politicians. Whether they are tipping points, however, is a point of contention.

“Hope for the unexpected.” This motto has pulled paleoclimatologist Gifford H. Miller to remote corners of the world to conduct fieldwork for more than half a century. Miller, a professor of geological sciences at the University of Colorado Boulder (CU) and associate director of the Institute for Arctic and Alpine Research, thrives on the pursuit of knowledge, asking tough questions about the global climate system whose answers have far-reaching implications. But it’s the thrill of unexpected discoveries — of which he’s made many — that keep him returning for more. His discoveries, including the extinction timing of giant birds in Australia, the existence of “zombie mosses” that document the life-cycle of Arctic ice caps, and the finding of lake sediments that tell the story of Iceland’s deglaciation, have led to advances in our understanding of Earth’s climate history and the role humans have played in it.

Geoengineering, the deliberate large-scale modification of environmental processes on Earth, is often proffered as a solution to climate change. The transfer of carbon long sequestered in geologic repositories to the atmosphere has raised greenhouse gases to levels unprecedented in the history of our species. As a result, the average surface temperature and the heat content of the oceans have both increased.

Stephen Mac­Avoy is an associate professor and chair of the environmental science department at American University in Washington, D.C. MacAvoy specializes in the urban environment found in his own backyard, studying urban water problems like stormwater overflow, which contributes to sewage and nutrient pollution, and the geochemistry of the degraded Anacostia River. He recently spoke with EARTH about how living “green” roofs can help reduce pollution in waterways, his surprising love of teaching and his advice for young scientists.