Acid Rain, the Greenhouse Effect and Ozone Depletion
Three different problems, three different sets of gases — never confuse them again
Three effects of pollution on climate and environment, taken strictly one at a time. Watch which gas does which.
Pollution affects climate and environment in three significant ways: acid rain, the greenhouse effect with global warming, and ozone layer depletion. They share no gas and no mechanism, so keep them apart from the start.
Free play — step through the process at your own pace, and move the slider to see what changes. Switch to when you're ready to test yourself.
What this lesson covers
What you do
- Say aloud which gas belongs to which problem before you look at the stage caption.
- Note that carbon dioxide appears in two of the three — in acid rain it dissolves and comes down, in the greenhouse effect it stays up and holds heat in.
Challenges to clear
- Step through all three phenomena from start to finish.
- Reach the stage that separates CFCs from the greenhouse gases.
- Get to the summary that holds all three apart.
The task
Three effects of pollution on climate and environment, taken strictly one at a time. Watch which gas does which.
What this lesson covers
- Three separate problems — Pollution affects climate and environment in three significant ways: acid rain, the greenhouse effect with global warming, and ozone layer depletion. They share no gas and no mechanism, so keep them apart from the start.
- Acid rain — the gases — Clean rain is already slightly acidic, with a pH of about 6, because of the carbon dioxide naturally in the air. Industrialisation adds much more carbon dioxide, sulphur dioxide and oxides of nitrogen, which dissolve in the falling rain drops. That is acid rain.
- Acid rain — the damage — Acid rain pollutes the soil and damages vegetation, decays building material and paints, and erodes ancient monuments, statues and sculpture as the acid reacts with their calcium. Fine sulphate and nitrate particles degrade visibility and harm health, and fish suffer as lakes and rivers grow more acidic.
- Greenhouse effect — the mechanism — A greenhouse is a small glass house for growing plants in cold winters: the glass lets sunlight in but does not let the heat escape, exactly as a car parked in the sun grows hot inside. Carbon dioxide and methane accumulating in the atmosphere do the same job to the whole planet.
- Greenhouse effect — global warming — More carbon dioxide is released by industry, by burning fuel in homes and by a rising population, while deforestation means less of it is taken up in photosynthesis. Over the last three decades the temperature of the atmosphere has risen by about 0.5 degrees Celsius, melting snow caps, raising sea level and cutting both crop yields and ocean fisheries.
- Ozone depletion — the mechanism — Ozone is an allotropic form of oxygen that forms a sunscreen high in the atmosphere. CFCs released from refrigerators, aerosol sprayers and styrofoam packing rise up and break into chlorine atoms, and each chlorine atom breaks ozone down into ordinary oxygen and a free oxygen atom.
- Ozone depletion — the consequence — A thinned ozone layer can no longer block the harmful ultra-violet rays known as UV-B. These reach the earth and cause sunburn, genetic disorders and skin cancers, and reduce the productivity of forests and of the sea. International Ozone Day is 16 September.
- Hold the three apart — Acid rain is sulphur dioxide and nitrogen oxides coming down dissolved in rain. The greenhouse effect is carbon dioxide and methane keeping heat from going out. Ozone depletion is CFCs letting UV-B rays come in. Different gases, different directions, different damage.
Hint
Ozone depletion does not cause global warming and greenhouse gases do not thin the ozone layer. CFCs attack ozone; carbon dioxide and methane trap heat; sulphur dioxide and nitrogen oxides acidify rain.