5.2 Greenhouse Effect

5.2.1 Draw and label a diagram of the carbon cycle to show the processes involved.

5.2.2 Analyse the changes in concentration of atmospheric carbon dioxide using historical records.

5.2.3 Explain the relationship between rises in concentrations of atmospheric carbon dioxide, methane and oxides of nitrogen and the enhanced greenhouse effect.

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.

5.2.6 Outline the consequences of a global temperature rise on arctic ecosystems.

5.2.1 Draw & Label! Carbon Cycle

1 of main elements of organic molecs (carbs, ptns, lipids)

found in 1 of 4 “pools”◦Biosphere◦Ocean◦Atmosphere◦Sediment

Moved b/w them by biolog., geochem., industrial processes

CARBON

Photosynthesis◦ Terr./aquatic; CO2 (atmosph/dissolved) removed &

fixed into org cmpds Respiration

◦ Metabolize org molecs, release CO2 Feeding

◦ C through trophic levels Fossilization

◦ C trapped in sediment as coal, gas, oil Combustion

◦ Burning of fossil fuels/biomass, release CO2

Carbon Cycle Processes

Greenhouse effect: ◦NATURAL process ◦creates moderate temps on earth (life’s

adapted)◦much less CO2 vs. Venus (200,000x more,

sfc temp = ~20x higher◦ Without it... avg global temperature would be

-17 C

5.2.3 EXPLAIN Atmospheric gases & greenhouse effect

a) Short wave solar radiation (light)

b) light penetrates the atmosphere and passes through the molecules of the atmosphere

c) Absorption by the ground and conversion to long wave infrared radiation (heat)

d)This warms the planet e) Some infrared is lost to

space as heat f) Atmospheric gases

particularly water vapor, carbon dioxide, methane and CFC's

g) Greenhouse gases absorb infra-red radiation and scatter this rather than letting it escape to space. In effect this traps the heat energy.

h) Some light reflects off the outer surface of the atmosphere and never enters

Human activities may be increasing CO2 levels & other G. gases (methane, N oxides)

May lead to increased global temps and climate change

ENHANCED G’hse. Effect

Increased greenhouse gases will increase the particles (f) in the diagram.

more IR will be absorbed, scattered and retained as heat

Avg global temps will rise. ◦ Some models: 40C in next 50 years

predicted to cause global climate changes “global warming” but while avg global

temps rise, local effects may vary

ENHANCED G’hse. Effect

Trends: ◦ indicators of potential climate change

Mauna Loa, HI since 1958 Now worldwide database:

http://cdiac.ornl.gov/trends/co2/sio-keel.htm Search “trace gas measurements”

5.2.2 ANALYZEHistorical Records—Atmospheric Gases

CO2’s released unevenly around world Distribution of Vegetation Lots of assumptions, factors affecting data

analysis BASIC TREND: increase Ancient ice core data—longer database,

variety of sources

Data Analysis

Temp determined by O isotopes (16:18)

Clear correlation b/w atm CO2 & temperature

DOESN’T mean causation

Levels today higher than ever in past

Dashed blue = extrapolation

Ice Cores: Bubbles trapped in ice, 1000s yrs ago!

“If the effects of human-induced change would be large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding.”

5.2.4 OUTLINE Precautionary Principle

Obligation actually falls on accused causers of climate change/enhanced greenhouse effect to show their actions are NOT damaging

If we wait til it’s proven....too late to reduce impacts

Better to respond now, even if in long term it turns out that case can’t be made!

PRECAUTIONARY Principle

5.2.5 EVALUATE P.P. and Greenhouse

Skeptic approach: ◦ envtalists need to give conclusive evidence

that ‘polluters’ are causing the harm PP:

◦ ‘polluters’ need to demonstrate that their actions DO NOT cause harm—govts, industries, communities, individuals!!

Hmmm--

Increased freq & intensity of droughts Flooding

◦ higher rainfalls, more snowmelts, rising sea levels Declines in food production Increased disease—

◦ (generally reduced by cold winters)...◦ Malaria & Dengue fever CURRENTLY extending

their distribution! More extreme weather Loss of biodiversity

Climate Effects—Predictions

Sea level simulation

External Links to websites of climate change. Weathervane, Environet, Climateark, GCRIO, UCSUSA, NET

External Links to reducing your carbon foot print Climatecrisis: calculate your carbon footprint.

Energy efficient appliances find out about reducing your energy demands in the house hold.

Simply insulate further information on positive responses to reducing your carbon foot print.

Cutting energy costs 10 ways to reduce your energy costs. Energy Audit a self help guide to performing an energy audit on your home. Standby energy leakage on those appliances that 'leak' power when left to

stand-by. Alternative energy sources alternative power sources to fossil fuels. maximize fuel efficiency from your car making the most of the fuel in your

driving. Hybridcars how hybrids work and a comparison with other methods. Alternative car fuels Biodiesel, ethanol and more to put in your tank. Fuel cell vehicles Hydrogen power fuel cells

Vulnerability and Adaptation to Climate Change in Developing Countries article by Chris Ward (30th July 2007) for the World Resources Institute,

considers fact that some are working towards own methods of adapting to climate change rather than how they will reduce climate change:

'Current scientific evidence shows, however, that some human-induced climate change is now inevitable and is in fact already occurring. which regions and groups are most vulnerable to predicted climate flux, how they might adapt to it

Bill Heal, The Arctic is an Ecosystem Article “Predicting changes over the next 50-100

yrs is difficult!...Most recent model...mean annual temp of Arctic will rise about 4 C this century...

...coniferous forest will expand –at expense of tundra

Tundra will be ½-ed by 2100 Will continue to be C-sink b/c increased

growth of forest will exceed increased decomposition

5.2.6 OUTLINE Greenhouse & Arctic

Google EarthClimate Change Tour