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 fuels Carbon cycles within an ecosystem  

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 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: nhouseeffect/ nhouseeffect/

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 20 th century had an effect on [CO2]?

Analyzing Data Explain the seasonal changes in [CO2].

Analyzing Data 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 effects CO2 stays in the atmosphere for longer before it breaks down It is produced in huge quantities Other 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 Arctic Temperatures and precipitation will increase Sea ice and habitat loss Snow cover decreases, permafrost melts and causes rising sea levels →flooding Increased rates of decomposition of detritus (non-living organic material) trapped in permafrost Shift in species present because new species migrate to the area to take advantage of new opportunities  New predator –prey relationships

Homework Outline the precautionary principle 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.