Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Key words: combustion, carbon dioxide, methane, deforestation

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Rising levels of carbon dioxide. Why?

At the moment the change is At the moment the change is seemingly very small seemingly very small

at 0.06at 0.0600C per yearC per year

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Objective

How does combustion affect the atmosphere?How does combustion affect the atmosphere?

Success Criteria

By the end of the lesson I:

• know how combustion affects the

atmosphere

• know how living organisms affect the

atmosphere

• can explain the consequences of global warming

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Get the gas right

Holes in the ozone layer

Sulfur dioxide and nitrogen oxides

Acid rain

Carbon dioxideGlobal warming

GasPollution problem

CFCs (Chloroflurocarbons)

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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The greenhouse effect

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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The greenhouse effect

Draw a diagram and explain the ‘greenhouse Draw a diagram and explain the ‘greenhouse effect’effect’

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Atmospheric carbon dioxide

The worry of rising carbon dioxide levels isThe worry of rising carbon dioxide levels isthat that

if the earth warms up then the ice capsif the earth warms up then the ice capswill melt causing sea levels to rise. will melt causing sea levels to rise.

There is no evidence of this happening There is no evidence of this happening

but it would meanbut it would meanthat low lying areas will flood and partsthat low lying areas will flood and partsof or even whole countries will become of or even whole countries will become

submerged!submerged!

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Carbon dioxide levels

•Burning fossil fuels (combustion), •deforestation and •flooding land for the construction of hydroelectric dams

have all contributed to rising levels of carbon dioxide.

Another greenhouse effect harming the environment is methane which is produced by cows in large amounts and by rice fields!

Carbon dioxide is one of the most important greenhouse gases because atmospheric concentrations have risen dramatically over the past century. Why do you think this is?

Respiration and combustion produceRespiration and combustion producecarbon dioxidecarbon dioxide

Photosynthesis removes carbon dioxidePhotosynthesis removes carbon dioxide

More rice fields and cattle have led toMore rice fields and cattle have led toincreased levels of methane in the increased levels of methane in the

atmosphere.atmosphere.

Increased levels of greenhouse gasesIncreased levels of greenhouse gases(carbon dioxide and methane) may (carbon dioxide and methane) may

cause global warming as a result of thecause global warming as a result of theGreenhouse effectGreenhouse effect

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Global warming and greenhouse gasesOne of the greatest threats caused by air pollution is global warming. Global warming is caused by a build-up of greenhouses gases, which leads to an increase in the Earth’s temperature.

A greenhouse gas is an atmospheric gas that absorbs infrared light.Key greenhouses gases include: carbon dioxide

(CO2) methane (CH4) water vapour (H2O)

nitrous oxide (N2O)

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Global warming• Carbon dioxide is Carbon dioxide is

released when fuels released when fuels like gas, coal, oil, like gas, coal, oil, petrol and wood are petrol and wood are burned.burned.

• Greenhouse gases Greenhouse gases cause the temperature cause the temperature of the Earth to rise of the Earth to rise slowly.slowly.

• This causes climate This causes climate change.change.

• Methane released from Methane released from cattle and rice fields is cattle and rice fields is also a greenhouse gas.also a greenhouse gas.

Most fuels contain carbon

Carbon dioxidereleased when fuel

burned

Extra carbon dioxide in the air slows downheat loss from Earth

Climate change

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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What is the carbon sink?Before the industrial revolution, carbon dioxide levels were usually kept in check by the carbon sink – forests and oceans that capture and store carbon. forests – All green plants absorb

carbon dioxide as part ofphotosynthesis. The absorbed carbonis only released back into the atmosphere when the plant dies and rots, or is burned.

oceans – Carbon dioxide dissolves insea water, depending on the temperatureand pressure. Tiny marine animals calledphytoplankton extract carbon from the carbon dioxide to make their skeletons and shells.

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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The carbon sink

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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DeforestationDeforestation can have a contributing

effect on global warming.Large scale deforestation (especially in

tropical areas) has led to an increase of carbon dioxide in the atmosphere (when trees die they release their CO2)

It has also reduced the amount of CO2 that is removed from the atmosphere

Leads to loss of biodiversity. some organisms lost may have been needed in the future!

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Preventing global warming

• Energy efficiency means less fuel Energy efficiency means less fuel burned to make electricity.burned to make electricity.

• Fuel cell buses.Fuel cell buses.• Renewable energy sources like water Renewable energy sources like water

power, solar, wind farms, bio fuels.power, solar, wind farms, bio fuels.• Nuclear power.Nuclear power.

• The Kyoto agreement to reduce COThe Kyoto agreement to reduce CO22 emissions.emissions.

• Reduction in large scale Reduction in large scale deforestationdeforestation

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Exam Questions

Give one reason why deforestation increases the carbon dioxide concentration of the atmosphere. (1 mark)

Explain, as fully as you can, why the increasing concentration of carbon dioxide in the atmosphere is causing global warming.

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Objective

How does combustion affect the atmosphere?How does combustion affect the atmosphere?

Success Criteria

By the end of the lesson I:

• know how combustion affects the

atmosphere

• know how living organisms affect the

atmosphere

• can explain the consequences of global warming