CLEAN > Teaching Climate & Energy > Teaching Climate > 3. Climate and Life
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Ganges River Delta
Satellite image of the Ganges River Delta. Image from the Earth as Art collection, courtesy of USGS National Center for EROS and NASA Landsat Project Science Office.

Teaching Essential Principle 3:
Life on Earth depends on, is shaped by, and affects climate.

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Teaching this principle is supported by five key concepts:

a. Individual organisms survive within specific ranges of temperature, precipitation, humidity, and sunlight. Organisms exposed to climate conditions outside their normal range must adapt or migrate, or they will perish.

b. The presence of small amounts of heat-trapping greenhouse gases in the atmosphere warms Earth's surface, resulting in a planet that sustains liquid water and life.

c. Changes in climate conditions can affect the health and function of ecosystems and the survival of entire species. The distribution patterns of fossils show evidence of gradual as well as abrupt extinctions related to climate change in the past.

d. A range of natural records shows that the last 10,000 years have been an unusually stable period in Earth's climate history. Modern human societies developed during this time. The agricultural, economic, and transportation systems we rely upon are vulnerable if the climate changes significantly.

e. Life—including microbes, plants, animals and humans—is a major driver of the global carbon cycle and can influence global climate by modifying the chemical makeup of the atmosphere. The geologic record shows that life has significantly altered the atmosphere during Earth's history.



Summary

The essence of this principle is that life affects the climate system and in turn, the climate dictates where and how species can survive. Life affects the composition of the atmosphere and therefore the climate because different life forms take in and release gases like carbon dioxide, methane and oxygen at different rates. Climatic conditions help to shape various ecosystems and habitats around the globe. A particular climate can be a boon to one species and a devastation to another. As the climate changes, species and ecosystems respond by adapting, migrating or reducing their population. Gradual shifts in the climate are easier to adapt to than abrupt swings, and this is certainly true for humans as well as other species. Studies of Earth's climatic history indicate that climates have changed in the past and resulted in dramatic shifts in ecosystems. The most recent geological period the Holocene (about last 10,000 years), however, has been unusually stable.

Penguins
Why are these topics important?

The manner in which the earth sustains life is of vital importance on many levels.

What makes these topics challenging to teach?

This principle ties in understanding of different scientific disciplines. Understanding the feedback between climate and life on Earth requires an understanding of biochemical processes like photosynthesis as well as basic climate science (eg. greenhouse effect). 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). Students might find it counter-intuitive that plants get their mass from the carbon in the air through photosynthesis (Private Universe study), which is one of the key concepts of the carbon cycle.

Teaching about the limited ability of organisms to adapt to climate change (eg. mass extinctions in geological past) should not lead to gloom-and-doom scenarios. Instead it can lead to an understanding that humans have a responsibility to stabilize the natural climatic conditions in order to preserve the environments in which humans and the surrounding ecosystems thrive.

When teaching about the feedback loops between climate and life and the effects of climate change, the differences between natural and human caused changes should be emphasized. It is likely that questions arise such as: Are all natural changes good? Are all human-caused effects bad? Is our current climate the "right climate? It will be important to emphasize that the recent increases in greenhouse gas concentrations in the atmosphere are unprecedented in the geologic past and to build an understanding of stewardship of the planet among students.


AAAS Benchmarks for Science Literacy

The AAAS Project 2061 Benchmarks for Science Literacy illustrate connections between concepts as well as how concepts build upon one another across grade levels.

Many of the CLEAN activities that teach Principle 3 fall within the evolution of life or the interdependence of life benchmarks.

Explore the map of climate and energy concepts for this principle (middle school):

Evolution of life
Interdependence of life

Learn more about the CLEAN maps of climate and energy concepts

How can I use this principle in my teaching?

Most ideas that are highlighted in this principle are part of the life science curriculum but integrate concepts previously introduced in physical sciences, geography and other disciplines. The key ideas in this principle build on the comprehension of the carbon cycle to understand the relationship between climate cycles, such as seasons, and biologic systems. Possible topics to teach an understanding of this principle are:

Another approach that may be engaging for older students is the delicate relationship between life and the climate. Many students will be surprised to learn of past mass extinction events and other sharp swings in the balance of the biosphere. This is a key place to discuss the role of humans in changing our environment and climate.

Middle school students in many parts of the world can observe the "green-up, green-down" seasonal process and participate in citizen science programs that encourage seasonal observations of migrating birds or butterflies, or when buds burst. See Blooming Thermometers for an example. Students can also learn about the impact of climate change on ecosystems and on animal habitats, as in Climate Change and Arctic Ecosystems.

In high school, students can learn about the global carbon cycle. This theme touches on many different processes such as photosynthesis, the formation of fossil fuels and the role of carbon dioxide in keeping Earth warm enough to sustain life. The Global patterns in Green-up and Green-down activity illustrates the global carbon cycle.

In the introductory undergraduate curriculum, students can use an Earth systems approach to learn how Earth operates in several "spheres." The evolution of the atmosphere and its relationship to early life is a suitable topic, as are group projects such as Understanding the Carbon Cycle: A Jigsaw Approach.

Upper-level college students can examine correlations between climate and life in a number of settings. For example, how did early humans adapt to the ice ages? How are climate perturbations expressed in various climate proxy data? What types of adaptations, migrations or population shifts are already being observed due to our warming climate?


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References

For more information see this article about the third principle from Encyclopedia of the Earth.

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 Cycle - NASA information - brief overview on the components of the carbon cycle.

Global Carbon Cycle - Information from NOAA and The Global Carbon Cycle - Information from US Global Climate Research Program USGCRP - provide brief and easy to understand summaries of the cutting edge research questions in this field.

Cititzen Science Project - Project Bud Burst - A citizen science project about the growth of plants throughout the season.

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







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