Climate Literacy Handbook: Principle 2
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| Principle 2. Climate is regulated by complex interactions among components of the Earth system. |
Essential Principle 2 relates to the complex interactions that drive climate processes. Interactions between land, snow and ice, living things, oceans, and the atmosphere generate the greenhouse effect and other climate processes. These interactions are inherently complex and interdisciplinary. Therefore, many key aspects of climate science may "fall between the cracks" of traditional science courses.
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Concept 2a. Earth’s climate is influenced by interactions involving the Sun, ocean, atmosphere, clouds, ice, land, and life. Climate varies by region as a result of local differences in these interactions. |
This concept relates to the idea that the climate is best understood from an Earth System perspective. All elements of the Earth as well as important components from space affect climate. The ideas in this concept are elaborated upon in several Essential Principles and concepts to follow.
Articles in Depth:
Teaching Aids and External Resources:
- Graphic Overview of Earth's Climate SystemA basic illustration of some of the most important components and interactions generating Earth's climate. From Paleoclimatology by William Ruddiman.
- Earth System ApproachAn overview of Earth System oriented course design for educators, from the Science Education Resource Center (SERC) of Carleton College.
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Concept 2b. Covering 70% of Earth's surface, the ocean exerts a major control on climate by dominating Earth's energy and water cycles. It has the capacity to absorb large amounts of solar energy. Heat and water vapor are redistributed globally through density-driven ocean currents and atmospheric circulation. Changes in ocean circulation caused by tectonic movements or large influxes of fresh water from melting polar ice can lead to significant and even abrupt changes in climate, both locally and on global scales. |
An entire course could be devoted to this fundamental concept alone. As David Herring writes for the NASA Earth Observatory:
The Earth's ocean and atmosphere are locked in such an intricate embrace--as one changes, so changes the other. At the interface between air and sea, there is a constant flow of information, as vast amounts of energy and chemicals (in the form of gases and aerosols) are continually being exchanged. If energy and chemicals are the languages that program the behavior of atmosphere and ocean, then regional and global scale climate variations are the outputs from this complex system. If scientists could learn to better interpret the "dialogue" between ocean and atmosphere, they could do a better job of predicting regional and global climate change.
Articles in Depth:
Teaching Aids and External Resources:
- Ocean and ClimateDavid Herring's full article exploring the connections between ocean and climate, from NASA.
- Ocean Literacy: The Essential Principles of Ocean SciencesEssential Principle 3 of this document (which served as the inspiration for the Climate Literacy document) concerns the interaction of ocean and climate. Additional Ocean Literacy documents, including scope and sequence of principles, and a robust community supporting ocean literacy are found at the Literacy Network.
- Lesson: Whither Arctic Sea Ice?In this lesson appropriate for grades 6-12, students explore changing sea ice conditions in the Arctic using an animation that shows 30 years of real satellite images and sea ice data. A part of the Earth Exploration Toolbook.
- Lesson: Ocean CirculationIn this college-level lesson, students view and analyze buoy, satellite, and temperature data to learn about ocean circulation and how it is related to atmospheric circulation. From San Francisco State University.
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Concept 2c. The amount of solar energy absorbed or radiated by Earth is modulated by the atmosphere and depends on its composition. Greenhouse gases - such as water vapor, carbon dioxide, and methane - occur naturally in small amounts and absorb and release heat energy more efficiently than abundant atmospheric gases like nitrogen and oxygen. Small increases in carbon dioxide concentration have a large effect on the climate system. |
In the middle of the 19th Century, scientist John Tyndall was studying the energy balance of the Earth, looking at incoming solar energy, primarily short-wave ultraviolet and visible light, and measuring that against outgoing infrared heat from the Earth after it has absorbed the energy from the sun. Tyndall set up an atmospheric laboratory in the basement of the Royal Institute in London and began experimenting with various trace gases in the atmosphere to determine their radiant properties. The primary gases in air— nitrogen (79%), oxygen (21%), and argon (~1%) make up 99.9% of the gas in the atmosphere. But none of them absorb light and reradiate infrared heat. Through his experiments, Tyndall determined that two gases in particular, water vapor (H2O) and carbon dioxide (CO2) do absorb light and reradiate heat. He published his findings, “Contributions to Molecular Physics in the Domain of Radiant Heat” in 1872. From this research the concept of the “Greenhouse Effect” as an important component of the Earth’s energy balance was developed. Tyndall’s laboratory experiments contributed to today’s detailed understanding of how solar energy drives the Earth’s climate system.
Articles in Depth:
- Greenhouse gas
- Greenhouse effect
- Methane
- Carbon dioxide
Teaching Aids and External Resources:
- The Greenhouse EffectAn article written for teachers, about the Earth's greenhouse and those of other planets. The article explains how the greenhouse effect is influenced by a number of factors, including clouds and the color and texture of the planet's surface. From UCAR.
- Animation: Greenhouse EffectThis animation sequentially illustrates the various interactions between the sun, Earth, and Earth's atmosphere that generate the greenhouse effect. From the Scripps Institute of Oceanography.
- Lesson: What is a Greenhouse?A controlled experiment whereby students can investigate the effects of a greenhouse. The experiment and the global greenhouse effect occur via different mechanisms, which is explained. From UCAR.
- Lesson: What Factors Influence a Greenhouse?An elaboration of the simpler UCAR lesson "What is a Greenhouse" which examines the effect of varying the greenhouse's colors and substrates, which is useful for teaching the concept of albedo and its effects on climate. From UCAR.
- Lessons: Greenhouse Gas and PhytoplanktonThree grade 6-12 appropriate activities from teacher Besse Dawson. Students generate of CO2 by burning a candle and observe the effect of this on temperature. They also can observe the ability of phytoplankton to remove CO2 from the atmosphere. From the Teachers Experiencing Antarctica and the Arctic (TEA) Project.
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Concept 2d. The abundance of greenhouse gases in the atmosphere is controlled by biogeochemical cycles that continually move these components between their ocean, land, life, and atmosphere reservoirs. The abundance of carbon in the atmosphere is reduced through seafloor accumulation of marine sediments and accumulation of plant biomass and is increased through deforestation and the burning of fossil fuels as well as through other processes. |
All biogeochemical cycles, including the hydrologic, nitrogen, oxygen, and phosphorus cycles, directly or indirectly relate to climate dynamics. Of these, the carbon cycle has been involved in long-term climatic change in geological history. Carbon cycling involves many carbon-containing compounds, including short term organic, long-term organic, and inorganic compounds. Biological processes involving the carbon cycle have relatively short time spans, influenced by photosynthesis and diurnal and annual cycles. On a longer time span, carbon dioxide is moved from the atmosphere and the ocean and into terrestrial deposits through biologic and geologic processes. Some carbon is transformed into calcium carbonate (limestone), the largest carbon reservoir on Earth.
Articles in Depth:
Teaching Aids and External Resources:
- Global Biogeochemical Cycles & the Physical Climate SystemA UCAR publication containing well written and illustrated overviews of biogeochemical cycles and their connections to climate. Particularly relevant chapters include Chapter 2 (Biogeochemical Cycles and Climate), Chapter 4 (Carbon Cycles) and Chapter 6 (The Water Cycle).
- Video Series: Global Warming: It's All About CarbonA five part series of humorous animated shorts that illustrate the central role that carbon plays in climate change. From NPR's Climate Connections series.
- Lesson: Carbon Cycle in the LabThis lesson uses examples of carbon-containing compounds to engage students in identifying how the carbon cycle is continually occurring in their environment. From the Royal Chemical Society.
- CO2 Weather Movies, scroll down to Hammer 2005This animation shows how CO2 concentration changes over one year. The NOAA data used to generate the animation is from all sources of CO2, both natural and manmade. It is useful for illustrating the strong annual change in carbon dioxide generated by the winter dormancy (net CO2 release, from decay) and summer productivity (net CO2 decrease, from photosynthesis) of Northern Hemisphere temperate forests.
- Interactive: Carbon Dioxide Time SeriesThis interactive data display allows the user to see how CO2 concentration has changed over many years, at any of NOAA's data collection sites around the world. Click "submit" to generate a CO2 graph over time for Mauna Loa, Hawaii. Change the site of data collection using the pull down menu on the left
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Concept 2e. Airborne particulates, called "aerosols", have a complex effect on Earth's energy balance: they can cause both cooling, by reflecting incoming sunlight back out to space, and warming, by absorbing and releasing heat energy in the atmosphere. Small solid and liquid particles can be lofted into the atmosphere through a variety of natural and man-made processes, including volcanic eruptions, sea spray, forest fires, and emissions generated through human activities. |
While the role of aerosols in the climate system has been known since the late 1800s, their complex interactions on climate are still being studied. Some may have a cooling effect in the short term but a warming effect in the long term. Black carbon (BC), an important aerosol, is now considered to be the second largest contributor to global warming after carbon dioxide. However, since it remains in the atmosphere for only days to weeks, reducing it before it enters the atmosphere may prove to be an efficient way to slow near-term climate change. (In contrast, CO2 stays in the atmosphere for hundreds of years.) However, when BC falls on snow or ice, it reduces the albedo of those surfaces. Albedo, meaning "whiteness", relates to the ability of a surface to reflect solar energy. Therefore, BC contributes to a positive feedback loop: as albedo is reduced, more radiation is absorbed by the surface, which leads to an increased rate of melting of snow and ice, which leads to even more reduced albedo. Burning of forests and savannahs and combustion of fossil fuels account for about 80% of black carbon, commonly known as soot, in the atmosphere.
Articles in Depth:
Teaching Aids and External Resources:
- Measuring Aerosols with the GLORY SatelliteThis educational NASA website for the GLORY research satellite includes an article about aerosols, news about the impact of aerosols on climate in China, and other classroom-appropriate resources.
- Volcanoes and Climate ChangeA short article describing how aerosols from volcanoes can alter the Earth's radiative balance and climate. From NASA's Earth Observatory.
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Concept 2f. The interconnectedness of Earth's systems means that a significant change in any one component of the climate system can influence the equilibrium of the entire Earth system. Positive feedback loops can amplify these effects and trigger abrupt changes in the climate system. These complex interactions may result in climate change that is more rapid and on a larger scale than projected by current climate models. |
Feedback loops are found in many natural processes, from the interworkings of hormones in the human body to the interworkings of climate. The relationship between Earth's energy balance, albedo, snow and ice cover, and greenhouse gases trapped under snow and ice generates a positive feedback loop that releases additional greenhouse gases as the planet warms. This is the primary reason why geological temperature records and CO2 records show simultaneous changes throughout Earth's history.
Abrupt climate change triggered by feedback loops in the climate system have occurred many times in Earth’s history. One of the most well-known examples of abrupt change is referred to as the Younger Dryas event or "Big Freeze", and it occurred 14,500 years ago as the Earth's climate began to shift from a cold glacial world to a warmer interglacial state. Partway through this transition, temperatures in the Northern Hemisphere suddenly returned to nearglacial conditions for about 1,300 years.
Articles in Depth:
- Radiative forcing
- Earth's climatic history
Teaching Aids and External Resources:
- Feedback LoopsA brief article describing albedo-related feedback loops that impact the Arctic climate. From the National Snow and Ice Data Center (NSIDC).
- Misconceptions About Abrupt Climate ChangeA "frequently asked questions" styled article about abrupt climate change, which is part of a compilation of related articles from Woods Hole Oceanographic Institute.
- A Paleo Perspective on Abrupt Climate ChangeThis website, appropriate for grades 9-12, describes the evidence for past abrupt climate change and explore some of the possible causes.
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