The Habitable Planet: A Systems Approach to Environmental Science
James J. McCarthy
James McCarthy is an Alexander Agassiz Professor of Biological Oceanography and director of Harvard University’s Museum of Comparative Zoology. He holds faculty appointments in the Department of Organismic and Evolutionary Biology and the Department of Earth and Planetary Sciences, and is the head tutor for degrees in environmental science and public policy. His research interests relate to the regulation of plankton productivity in the sea, in particular the cycling of nitrogen in planktonic ecosystems. He was the founding editor of the American Geophysical Union (AGU) Global Biogeochemical Cycles journal. For the past five years he has served as co-chair of the Intergovernmental Panel on Climate Change (IPCC), Working Group II, which has responsibilities for assessing impacts of, and vulnerabilities to, global climate change. He has been elected a fellow of the American Association for the Advancement of Science, a fellow of the American Academy of Arts and Sciences, and a foreign member of the Royal Swedish Academy of Sciences. In 1997, he was the recipient of the New England Aquarium’s David B. Stone award for distinguished service to the environment and the community.
Mark A. Cane
Mark Cane is the G. Unger Vetlesen Professor of Earth and Climate Sciences in Department of Earth and Environmental Sciences and Department of Applied Physics and Applied Mathematics at Columbia University, where he also holds joint appointment in the International Research Institute for Climate and Society (IRI) and serves as a member of the IRI’s International Science and Technical Advisory Committee. Cane received his Ph.D. in Meteorology from Massachusetts Institute of Technology in 1975. With his colleague Dr. Stephen Zebiak, Mark devised the first numerical model able to simulate El Niño and the Southern Oscillation (ENSO), a pattern of interannual climate variability centered in the tropical Pacific but with global consequences. In 1985 this model was used to make the first physically based forecasts of El Niño. Over the years the Zebiak-Cane model has been the primary tool used by many investigators to enhance understanding of ENSO. Dr. Cane has also worked extensively on the impact of El Niño on human activity, especially agriculture. In 1992 Dr. Cane received the Sverdrup Gold Medal of the American Meteorological Society. He is a fellow of the American Meteorological Society, the American Association for the Advancement of Science, the American Geophysical Union, and the American Academy of Arts and Sciences. His current research is focused on the variations in the paleoclimate record, especially abrupt changes, and on the impact of climate variability on human activities, especially agriculture and health.
Sallie W. “Penny” Chisholm
Penny Chisholm is Lee and Geraldine Martin Professor of Environmental Sciences at the Massachusetts Institute of Technology. As a biological oceanographer, her research interests include ocean ecology, the evolution and comparative genomics of marine cyanobacteria and the viruses that infect them, iron and phytoplankton growth, and ocean fertility. Her work on the abundant marine phytoplankton, Prochlorococcus, first described in 1988, has led to a deeper understanding of microbial ecology and the oceanic carbon cycle.
3.1 Oceans Video
Ocean systems operate on a range of scales, from massive systems such as El Niño that affects weather across the globe to tiny photosynthetic organisms near the ocean surface that take in large amounts of carbon dioxide. This program looks at how ocean systems regulate themselves and thus help maintain the planet's habitability.
Unit 1 Many Planets, One Earth
Astronomers have discovered dozens of planets orbiting other stars, and space probes have explored many parts of our solar system, but so far scientists have only discovered one place in the universe where conditions are suitable for complex life forms: Earth. In this unit, examine the unique characteristics that make our planet habitable and learn how these conditions were created.
unit 2 Atmosphere
The atmosphere is what makes the Earth habitable. Heat-trapping gases allow ecosystems to flourish. While the NOAA Global Monitoring Project documents the fluctuations in greenhouse gases worldwide, MIT's Kerry Emanuel looks at the role of hurricanes in regulating global climate.
Unit 3 Oceans
Oceans cover three-quarters of the Earth's surface, but many parts of the deep oceans have yet to be explored. Learn about the large-scale ocean circulation patterns that help to regulate temperatures and weather patterns on land, and the microscopic marine organisms that form the base of marine food webs.
Unit 4 Ecosystems
Why are there so many living organisms on Earth, and so many different species? How do the characteristics of the nonliving environment, such as soil quality and water salinity, help determine which organisms thrive in particular areas? These questions are central to the study of ecosystems—communities of living organisms in particular places and the chemical and physical factors that influence them. Learn how scientists study ecosystems to predict how they may change over time and respond to human impacts.
Unit 5 Human Population Dynamics
What factors influence human population growth trends most strongly, and how does population growth or decline impact the environment? Does urbanization threaten our quality of life or offer a pathway to better living conditions? What are the social implications of an aging world population? Discover how demographers approach these questions through the study of human population dynamics.
Unit 6 Risk, Exposure, and Health
We are exposed to numerous chemicals every day from environmental sources such as air and water pollution, pesticides, cleaning products, and food additives. Some of these chemicals are threats to human health, but tracing exposures and determining what levels of risk they pose is a painstaking process. How do harmful substances enter the body, and how do they damage cells? Learn how dangers are assessed, what kind of regulations we use to reduce exposures, and how we manage associated human health risks.
Unit 7 Agriculture
Demographers project that Earth's population will peak during the 21st century at approximately ten billion people. But the amount of new cultivable land that can be brought under production is limited. In many nations, the need to feed a growing population is spurring an intensification of agriculture—finding ways to grow higher yields of food, fuel, and fiber from a given amount of land, water, and labor. This unit describes the physical and environmental factors that limit crop growth and discusses ways of minimizing agriculture's extensive environmental impacts.
unit 8 Water Resources
Earth's water resources, including rivers, lakes, oceans, and underground aquifers, are under stress in many regions. Humans need water for drinking, sanitation, agriculture, and industry; and contaminated water can spread illnesses and disease vectors, so clean water is both an environmental and a public health issue. In this unit, learn how water is distributed around the globe; how it cycles among the oceans, atmosphere, and land; and how human activities are affecting our finite supply of usable water.
unit 9 Biodiversity Decline
Living species on Earth may number anywhere from 5 million to 50 million or more. Although we have yet to identify and describe most of these life forms, we know that many are endangered today by development, pollution, over-harvesting, and other threats. Earth has experienced mass extinctions in the past due to natural causes, but the factors reducing biodiversity today increasingly stem from human activities. In this unit we see how scientists measure biodiversity, how it benefits our species, and what trends might cause Earth's next mass extinction.
unit 10 Energy Challenges
Global energy use increases by the day. Polluting the atmosphere with ever more carbon dioxide is not a viable solution for our future energy needs. Can new technologies such as carbon sequestration and ethanol production help provide the energy we need without pushing the concentrations of CO2 to dangerous levels?
Unit 11 Atmospheric Pollution
Many forms of atmospheric pollution affect human health and the environment at levels from local to global. These contaminants are emitted from diverse sources, and some of them react together to form new compounds in the air. Industrialized nations have made important progress toward controlling some pollutants in recent decades, but air quality is much worse in many developing countries, and global circulation patterns can transport some types of pollution rapidly around the world. In this unit, discover the basic chemistry of atmospheric pollution and learn which human activities have the greatest impacts on air quality.
Unit 12 Earth’s Changing Climate
Earth's climate is a sensitive system that is subject to dramatic shifts over varying time scales. Today human activities are altering the climate system by increasing concentrations of heat-trapping greenhouse gases in the atmosphere, which raises global temperatures. In this unit, examine the science behind global climate change and explore its potential impacts on natural ecosystems and human societies.
Unit 13 Looking Forward: Our Global Experiment
Emerging technologies offer potential solutions to environmental problems. Over the long-term, human ingenuity may ensure the survival not only of our own species but of the complex ecosystems that enhance the quality of human life. In this unit, examine the wide range of efforts now underway to mitigate the worst effects of man-made environmental change, looking toward those that will have a positive impact on the future of our habitable planet.