IB BIOLOGY

5.2 The greenhouse effect

The Carbon Cycle

Carbon exists in many forms: Atmospheric gases (CO2 and Methane- CH4) Dissolved CO2 in aquatic ecosystems Organic carbon in living organisms Carbon deposits in lithosphere as carbonates and

fossil fuelsCarbon cycles within an ecosystem

http://www.nodvin.net/snhu/SCI219/demos/Chapter_3/ http://www.brainpop.com/science/earthsystem/carbon

cycle/

Draw a Carbon Cycle

Carbon pool – system that has the capacity to store and release carbon

Carbon sink – system that has more carbon flowing into it than out of it

Draw a carbon cycle Use text pg 178 to guide you

Greenhouse gases

Greenhouse gases include: Carbon dioxide (CO2) Methane (CH4) Nitrous oxide (NO2) Water vapour

GGs are trapped in the troposphere (16km) above Earth’s surface

Greenhouse gases then trap IR radiation (heat) from the sun, raising the temperature of Earth so it can sustain life

This is a natural phenomenon called the greenhouse effect

Human influence

Enhanced greenhouse effect due to human activities

More radiation is absorbed and re-emitted to Earth Combustion of

fossil fuels

Deforestation

Increased industry

More cars

CFCs

http://www.ucsusa.org/global_warming/science_and_impacts/science/faq-videos.html#video-1

Greenhouse Effect

1. The sun emits energy (radiation) to Earth in the form of visible, infrared (IR) and ultraviolet light (UV)

2. Visible light has short wavelengths and passes through the atmosphere

3. Solar energy is absorbed by Earth and passed back to the atmosphere as IR heat. Some IR goes back into space.

4. IR that is trapped in atmosphere by GGs is re-emitted back to Earth’s surface as heat

Animation: http://www.brainpop.com/science/earthsystem/greenhouseeffect/

Mauna Loa, Hawaii

CO2 levels in the atmosphere have been measured in Hawaii since 1958 by Charles Keeling

See the rising trend in CO2 in the atmosphere over the past 50 years

What significant event in the 20th century had an effect on [CO2]?

Analyzing Data

Explain the seasonal changes in [CO2].

Explain the seasonal changes in [CO2].

Analyzing Data

Explain the seasonal changes in [CO2].

Explain the seasonal changes in [CO2].

PEAKS - Higher [CO2] in winter/spring – Oct -May b/c less foliage taking up CO2

TROUGHS -Lower in summer/fall– Jun-Sept b/c more foliage taking up CO2

Ice Core Data

Analyze atmospheric gas bubbles trapped in ice from Greenland

Ice deeper down is older than ice near the surface

Relative warming and cooling effectsCO2 stays in the atmosphere for longer before it

breaks downIt is produced in huge quantitiesOther gases the CFCs have the potential to be more

harmful but are produced in smaller amounts

What will happen to the Arctic?

Consequences of global temperature rise

ArcticTemperatures and precipitation will increaseSea ice and habitat lossSnow cover decreases, permafrost melts and causes

rising sea levels →floodingIncreased rates of decomposition of detritus (non-

living organic material) trapped in permafrostShift in species present because new species migrate

to the area to take advantage of new opportunities New predator –prey relationships

http://www.arctic.noaa.gov/reportcard/index.html

Homework

5.2.4 Outline the precautionary principle

5.2.5 Evaluate the precautionary principle as a justification for strong action in response to the threats posed by the enhanced greenhouse effect

Response should include economic, moral and social reasons. Cite another area of society that uses the precautionary principle.