Global Atmospheric Change
Solar Energy and Living Things
Life on Earth depends directly or indirectly on energy from the sun. Solar energy, which reaches us as heat, light and other types of electromagnetic radiation (such as ultraviolet, or UV, radiation), also can be harmful to living things.
Most of the energy we use each day comes in some way from materials photosynthesized by plants and other producers, such as algae. During photosynthesis, energy from the sun is trapped to build molecules necessary for life. The oil, natural gas and coal that have been essential for the development of our modern industrial world all are made up of the remains of dead organisms that relied on photosynthesis. Similarly, all of our food, which provides energy for our bodies, ultimately comes from plants and other producers— whether we eat plants directly or eat other organisms that consume plants.
The pathway of energy through Earth’s living and non-living systems closely parallels the routes followed by carbon in the carbon cycle. This simple element (the fourth most abundant element in the universe) forms the backbones of the molecules produced and used by all living things—from DNA to fossil fuels. Plants and similar organisms create food molecules from carbon dioxide (CO2), water and energy from the sun. They use this energy to drive all other processes necessary for life. When carbon-containing substances (wood, oil, natural gas or coal, for example) are burned, CO2 is released back into the atmosphere. Similarly, when living cells use the chemical energy stored in food, CO2 is released. This process is known as respiration.
Shorter wavelengths of solar radiation (such as UV radiation) can damage cells. This is important because more UV radiation is reaching Earth’s surface as a result of ozone depletion in the stratosphere. Stratospheric ozone, which absorbs UV radiation, is destroyed by certain chemicals, particularly those known as chlorofluorocarbons (CFCs). Exposure to UV radiation can increase a person’s chances of getting skin cancer or of developing cataracts. Other organisms, from frogs to marine algae, also can be harmed by UV radiation.
It is particularly important to protect skin from the sun. Less than one millimeter in thickness, skin plays an essential role in the body. It protects inner tissues and provides communication (through the sensory system) with the outside environment. The skin also aids in maintaining a constant temperature within the body. The numerous blood vessels in the skin and sweat glands help cool the body when outside temperatures are warm.
The skin is composed of layers, each with different characteristics. The layers of skin act like thin boards pressed together in a sheet of plywood, giving skin greater strength than it would have otherwise.
Keywords: lesson | life science | environment | atmosphere | climate | weather | global change | greenhouse gas | ozone | sun | Earth | ecology | pollution | radiation | fossil fuel | CO2 | combustion | temperature | skin | skin damage | UV light | sunscreen | solar energy
- Photo courtesy of NASA.
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Global Atmospheric Change Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-75-0.
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Funded by the following grant(s)
My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education