Image of our planet Earth from space. © NASA

How do we begin to care for and protect our environment? For Carl Sagan, outer space is the perfect place to start. The astronomer explicitly requested that the Voyager spacecraft, on its way out of the solar system, point its camera backwards toward Earth. Sagan coined the phrase "the pale blue dot" to describe the resulting image of our planet floating in the void. In his book of that name, the astronomer wrote, "There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we've ever known."

Dr. Mordecai-Mark MacLow, Assistant Curator, Department of Astrophysics © AMNH

Since Sagan wrote those words in 1994, astrophysicists and planetary scientists have learned a great deal about the place of the Earth in the universe. They've discovered other planetary systems, and the laws of physics and chemistry tell them that life could certainly develop or exist elsewhere. But unless it lies deep under the surface of Mars's or Jupiter's moons, from what we think or know right now, life is not supported anywhere else in our solar system, a fact that makes the variety of life on Earth "very uncommon in the local Universe," says Dr. Mordecai-Mark MacLow, Assistant Curator in the Museum's Department of Astrophysics. "What we don't know is whether any other planets out there could support life, or at least life in a form that we could recognize." Even if such planets exist, and await discovery, "the Earth is small, and it's the only one we know about, so let's be careful with it."

Although most geological change occurs across vast reaches of time, the fossil record indicates that such change isn't always incremental. And while much of the fate of the planet does not lie in human hands, mounting evidence indicates that human activity is indeed altering global climate. "We don't really know what the results of those changes will be, but we know that previous perturbations due to natural factors have produced drastic results, and we know that we are perturbing it at the same level," Mordecai observes.

Dr. Ed Mathez, Curator, Department of Earth and Planetary Sciences © AMNH

Dr. Ed Mathez, a Curator in the Department of Earth and Planetary Sciences, seconds his colleague's concern about the impact of climate change on the environment. "How the climate works is a basic question that is fundamental to understanding how the Earth works. It is particularly important to understand the interaction between the ocean and the atmosphere, as they transport heat around the Earth," says Ed. Precisely because we don't know how this system works, "climate change is probably the single most serious issue we face."

Records of past climate from ice cores, coral, tree rings, and lake and deep-sea sediments, create a composite picture that reveals dramatic shifts into very different long-term climate modes, some warmer and some very cold. While we do know what mode we are in currently, Ed explains that "the question is, how much carbon dioxide and other greenhouse gases can be loaded into the atmosphere before the climate shifts into a different mode? A new mode may bring rapid changes that influence how we live, crop production, and so on." He adds, "When we gain a better understanding of how this complex, dynamic system works, and how human activities affect global climate, then we can make the difficult political decisions that rest on that information."

To an astrophysicist like Mordecai, a million years is a short time. It's also a relatively brief period for most Earth processes. A canyon can erode in a few tens of centuries and a volcano will literally blow its top off in just a few hours. But, those in the life sciences hear the clock ticking loudly. To Dr. Mike Novacek, paleontologist and Provost of the Museum, the operative time frame is decades. "The living planet is under threat from the loss of species and habitat," he declares. According to Mike, the scale of the threat is immense, "perhaps rivaling the great extinction events of the past," and its speed unparalleled. Although endangerment has become widespread only during the last 150 years, some experts forecast that by the mid-21st century, we may have lost between 30 and 50 percent of all species on Earth. At risk are not just bacteria, plants, and animals, but the complex web of life they sustain and depend upon.

To Mike, as to his fellow scientists, the remedy is clear: a greater understanding of how the planet works. "A lot of conservation decisions are ill informed," Mike says frankly. "To make important decisions about our future, we need to know the facts. Embarrassingly little is known about the total number of species on the planet." For instance, he points out that there are only about ten biologists in the world studying algae, a group of enormous ecological importance and possibly economic significance as well. Scientists are just beginning to understand the role microbes play in human health and in ecosystems. "We face an enormous exploratory enterprise. And we need more recruits," Mike says.

Left: Dr. Mike Novacek, Museum Provost and Curator, Division of Paleontology © AMNH Right: Mike digs for fossils in the red sandstone of the Gobi Desert in Mongolia. © Discovery Channel Online

This issue of Musings steps up to the plate with tools, tips, stories, and information from Museum professionals and their colleagues whose goal is to promote environmental stewardship. It is our hope that the work of these scientists and educators will inspire—through our readers—a new generation of expert and energetic scientists and conservationists.

© 2002 American Museum of Natural History