The Habitable Planet: A Systems Approach to Environmental Science
Professional Development > The Habitable Planet: A Systems Approach to Environmental Science > 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.
Interactive Labs
Carbon Lab (Units 1-3, 13)
Throughout this course, the carbon cycle is featured as one of the most important planetary systems. This lab uses a robust model of the carbon cycle to give you an intuitive sense for how the system works. It also allows you to experiment with how human inputs to the cycle might change global outcomes to the year 2100 and beyond. One especially relevant human impact is the increase in atmospheric CO2 levels. Between 1850 and today, atmospheric concentrations have risen from 287 ppm (parts per million) to over 380 ppm a level higher than any known on Earth in more than 30 million years (see Unit 12 to find out how scientists measure ancient atmospheric carbon levels). You will experiment with the human factors that contribute to this rise, and see how different inputs to the carbon cycle might affect concentrations of the greenhouse gas CO2. launch lab
Unit 3: Oceans // Glossary
biological pump
The sum of a suite of biologically-mediated processes that transport carbon from the surface euphotic zone (the depth of the water that is exposed to sufficient sunlight for photosynthesis to occur) to the ocean's interior.
A relatively rapid increase in the population of (usually) phytoplankton algae in an aquatic system. Algal blooms may occur in freshwater or marine environments.
The upward force on an object produced by the surrounding fluid (i.e., a liquid or a gas) in which it is fully or partially immersed, due to the pressure difference of the fluid between the top and bottom of the object.
compensation depth
Depth at which light intensity reaches a level at which oxygen evolved from a photosynthesizing organism equals that consumed by its respiration.
compensation zone
The point at which there is just enough light for a plant to survive. At this point all the food produced by photosynthesis is used up by respiration. For aquatic plants, the compensation point is the depth of water at which there is just enough light to sustain life (deeper water = less light = less photosynthesis).
The apparent force, resulting from the rotation of the Earth, that deflects air or water movement.
Ekman transport
The change in wind direction with altitude caused by the varying effect of surface friction.
El Niño Southern Oscillation (ENSO)
A global event arising from large-scale interactions between the ocean and the atmosphere, usually an oscillation in the surface pressure (atmospheric mass) between the southeastern tropical Pacific and the Australian-Indonesian regions.
A large group of amoeboid protists with reticulating pseudopods—fine strands of cytoplasm that branch and merge to form a dynamic net. They typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in structure.
A circular or spiral motion, especially a circular ocean current.
A general circulation pattern in which air rises near the equator, flows north and south away from the equator at high altitudes, sinks near the poles, and flows back along the surface from both poles to the equator.
marine snow
The tiny leftovers of animals, plants, and non-living matter in the ocean's sun-suffused upper zones. Among these particles are chains of single-celled plants called diatoms, shreds of zooplankters' mucous food traps, soot, fecal pellets, dust motes, radioactive fallout, sand grains, pollen, and pollutants. Microorganisms also live inside and on top of these odd-shaped flakes.
North Atlantic Oscillation (NAO)
A major disturbance of the atmospheric circulation and climate of the North Atlantic-European region, linked to a waxing and waning of the dominant middle-latitude westerly wind flow during winter.The NAO Index is based on the pressure difference between various stations to the north (Iceland) and south (Azores) of the middle latitude westerly flow. It is, therefore, a measure of the strength of these winds.
Pacific Decadal Oscillation (PDO)
A pattern of Pacific climate variability that shifts phases on at least inter-decadal time scale, usually about 20 to 30 years. The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of lat. 20° N. During a "warm" or "positive" phase, the west Pacific becomes cool and part of the eastern ocean warms; during a "cool" or "negative" phase, the opposite pattern occurs.
Microscopic plants that live in the water column of oceans, seas, and bodies of fresh water and are the foundation of the marine food chain.
The amount of heat, measured in calories, required to raise the temperature of one gram of a substance by one Celsius degree.
A layer within a body of water or air where the temperature changes rapidly with depth.The thermocline varies with latitude and season: it is permanent in the tropics, variable in the temperate climates (strongest during the summer), and weak to nonexistent in the polar regions, where the water column is cold from the surface to the bottom.
The global density-driven circulation of the oceans.
upwelling
An oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-deplete surface water.
An atmospheric circulation of air at the equatorial Pacific Ocean, responsible for creating ocean upwelling off the coasts of Peru and Ecuador. This brings nutrient-rich cold water to the surface, increasing fishing stocks.
Microscopic animals that live in the water column of oceans, seas, and bodies of fresh water. The smallest zooplankton can be characterized as recyclers of water-column nutrients and often are closely tied to measures of nutrient enrichment. Larger zooplankton are important food for forage fish species and larval stages of all fish.
1 Many Planets, One Earth
1 Many Planets, One Earth Video
2 Online Textbook
3 Scientists
4 Interview with Andy Knoll
5 Interview with Paul Hoffman
2 Atmosphere
1 Atmosphere Video
4 Interview with Kerry Emanuel
5 Interview with Pieter Tans
3 Oceans
1 Oceans Video
4 Interview with Mark Cane
5 Interview with Penny Chisholm
1 Ecosystems Video
4 Interview with Robert Crabtree
5 Interview with Stuart Davies
5 Human Population Dynamics
1 Human Population Dynamics Video
2 Online Textbooks
4 Interview with Deborah Balk
5 Interview with Martha Farnsworth Riche
6 Risk, Exposure, and Health
1 Risk, Exposure, and Health Video
4 Interview with Howard Hu
5 Interview with Robin M. Whyatt
1 Agriculture Video
4 Interview with Peter Kenmore
5 Interview with Pam Matson
8 Water Resources
1 Water Resources Video
4 Interview with Wendy Graham
5 Interview with Tom Maddock
9 Biodiversity Decline
1 Biodiversity Decline Video
4 Interview with Jeremy B. C. Jackson
5 Interview with William F. Laurance
10 Energy Challenges
1 Energy Challenges Video
4 Interview with John Holdren
5 Interview with Andy Aden
6 Interview with Neeraj Gupta
11 Atmospheric Pollution
1 Atmospheric Pollution Video
4 Interview with Charles Kolb
4 Interview with Luisa T. Molina
12 Earth's Changing Climate
1 Earth's Changing Climate (video)
4 Interview with Chris Field
5 Interview with Lonnie Thompson
13 Looking Forward: Our Global Experiment
1 Looking Forward: Our Global Experiment Video
4 Interview with Daniel Pauly
5 Interview with Edward O. Wilson
14 Carbon Lab
15 Demographics Lab
16 Disease Lab
17 Ecology Lab
18 Energy Lab
Harvard Smithsonian Center for Astrophysics in association with the Harvard University Center for the Environment. 2007.
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.
3.2 Online Textbook
3.3 Scientists
3.4 Interview with Mark Cane
3.5 Interview with Penny Chisholm
Gallery: Unit 3 Visuals
Photographs & Graphics
Animations: Unit 3 Animations
PDF: Professional Development Guide
Professional Development Guide
PDF: Printable Online Text
Printable Online Text
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
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.
interactive 14 Carbon Lab
interactive 15 Demographics Lab
interactive 16 Disease Lab
interactive 17 Ecology Lab
interactive 18 Energy Lab