This principle addresses some of the natural complexities of our climate system and builds a foundation for the understanding of key components of the climate system such as the carbon cycle, the greenhouse effect, and interactions and feedback loops. It includes some of very active areas of climate research, including important topics such as:

How aerosols affect climate:
This principle explores the complex role aerosols play in the changing climate. These small airborne particles have both a cooling and warming effect and originate from both natural and human-caused sources. (Principle 3e)

How feedback loops affect climate:
Positive and negative feedbacks in the climate system contribute to the effects of increasing atmospheric CO2. (Principle 3f)

How oceanic processes help drive the climate system:
How oceanic processes are integral in the distribution of heat, absorption of CO2 and changes in circulation patterns. (Principle 3b)

How past climate changes have played out:
Why some past climate changes have been gradual and others abrupt.

How climate varies by region.
How local differences in clouds, ice, land, water, and life give rise to regional variations in climate. (Principle 3a)

Source: Climate Literacy & Energy Awareness Network

The natural greenhouse effect is a common area of students' prior concepts or misunderstandings. For example, grasping the greenhouse effect requires comprehension of several principles, each drawn from a different area of the sciences:

• The basics of atmospheric structure and composition, including the concept that air has mass (Earth science).
• The properties of gases, particularly those gases that can trap infrared heat due to their number of bonds and their ability to absorb and release energy (resonant frequency) (chemistry/physics).
• Electromagnetic radiation, particularly the difference between incoming short wave and outgoing long wave energy (physics).

Furthermore, students may confuse the natural greenhouse effect that makes life on Earth possible with the enhancement of the effect by the emission of greenhouse gases from fossil fuel burning (McCaffrey & Buhr, 2008). Understanding heat transfer is challenging for many learners, and the greenhouse effect is difficult even for adults to grasp. Attempts to oversimplify the greenhouse effect can be counter-productive and further confuse learners. For younger students the mental model of how the natural greenhouse effect is like a "blanket" that keeps heat under the covers may be appropriate, but by high school and certainly college students should have a clearer understanding of the mechanics of the greenhouse effect. This concept is essential to understanding how human activities are impacting the climate system.

Full comprehension of the carbon cycle requires an understanding of biogeochemical systems. Students also have to understand the different time scales at which carbon exchange takes place in the different reservoirs. Learning about the carbon cycle lays an important foundation to the understanding of the impact of burning fossil fuels. As shown in the famous Harvard Private Universe study, students struggle to build the connection between mass production through photosynthesis and carbon uptake, the burial of biomass and fossil fuels - all these concepts are part of the carbon cycle.

The terminology of positive and negative feedback in a system can often lead to misunderstandings. In Earth system sciences feedback loops described changes in a system, positive feedback loops enhance or amplify changes, negative feedbacks tend to dampen or buffer changes. Positive and negative are not used as a value statement as they are in the colloquial use of these words.

Source: Climate Literacy & Energy Awareness Network

Just because a process is "complex" does not mean it needs to be complicated. Teaching these basic climate science topics may be best handled by an approach that allows depth over breadth. If students are able to address a single topic with sufficient depth, they can come to an understanding about nuances like feedback loops or deep ocean circulation. So a good tactic would be to set aside time to explore a topic and several facets within it. An important part of climate literacy is an appreciation for scientific complexity, and even young learners can comprehend that a seemingly simple and linear process can be quickly complicated by other factors.

Another strategy for teaching these principles is the Earth systems science approach. This method teaches students about the "spheres" of the Earth system: the atmosphere, cryosphere, geosphere, and biosphere. An Earth Systems approach is an effective way to illustrate the interplay between different components of Earth and that processes do not occur in isolation.

Middle school students can study some of the basic physics of climate including heat transfer of various substances (as in Energy Flows). Applications of this concept include the albedo of different surfaces (see Understanding Albedo), the heat-trapping qualities of certain gases, and how thermal energy carried by ocean currents can influence on local climates around the world. Students can also begin to appreciate micro-climates around the school and in their communities, and start to grasp the world's geography and global dynamics.

In high school, students can learn about the relationship between Earth's climate and life. The role of the oceans, for example, would make an appropriate medium to study many aspects of the climate system, as is illustrated by the activity Ocean Currents and Sea Surface Temperature. Students can also learn about different aspects of the carbon cycle and understand the nature and the dynamics of the greenhouse effect and heat-trapping properties of different gases.

The introductory undergraduate curriculum is an ideal setting to help students gain a firm grasp of what the greenhouse effect is and is not. Furthermore, college students can also learn about feedbacks within the climate system and the role of aerosols. See Tropical Atlantic Aerosols. Simple climate models can be used to introduce students to the complex interactions and feedbacks between different parts of the climate system.

Upper-level college students can approach complex climate interactions via their specific field of study. Biology students can examine the carbon cycle or changes in the albedo of land surfaces under various types of plant cover. Students in the geosciences can investigate how the evolution of life on Earth has shaped the climate since the PreCambrian. The complex role of aerosols, which can act to either warm or cool the atmosphere, can provide an interesting and engaging topic for physics students. Example: Exploring the Link between Hurricanes and Climate using GCM Results.

Source: Climate Literacy & Energy Awareness Network

IPCC Fourth Assessment Report 2007, Working Group I: The Physical Basics - Chapter 2: Changes in Atmospheric Constituents and in Radiative Forcing - scientific summary of the latest state of the scientific knowledge on this topic with a special focus on the human impact on the climate system.

Carbon and Climate - an educational website with a carbon cycle applet for modeling your own projection on carbon emissions and future carbon sinks.

McCaffrey & Buhr, 2008: Clarifying Climate Confusion.- journal article in Physical Geography about common misconceptions in climate science.