1. Human influence on climate
Power point 2
Global systems
6.3 Pearsons

2. Science for fun activity
Melting icebergs
Pg 194 Pearsons - do as demo…ice in freezer
Is the earth actually warming?????? The burning question
All indicators point to we are in a “warming” state
was the warmest
Increases in air and ocean temp
Widespread melting of snow and ice
Rising global sea levels

3. Enhanced Greenhouse Effect
Many believe that human activity is having significant effect on rate and intensity of global warming- climate change
We have only measured for little over a century-climate change takes many, many years –so difficult to tell the exact effect of changes caused by humans
Thought to be natural but enhanced by the increase in carbon dioxide methane and nitrous oxide concentrations in the atmosphere-by humans/activity

4. C02 in the Atmosphere
95% of atmospheric C02 would be present without human contribution
Most is from decaying forests and grasslands
Balanced by natural carbon sinks- places/events that remove C02 from the atmosphere
Following industrialisation atmospheric oxygen has increased enormously

5. COAL AND GAS-major carbon sinks
But as we have burned much of the coal/gas putting carbon back into the atmosphere but not being able to remove at the same rate we have upset the balance…

6. Australia United States India China 22.3 400 307.0 5990 1140.0 1140
COUNTRY
POPULATION
(MILLIONS)
TOTAL CO2 OUTPUT
(MILLLIONS OF TONNES)
Australia
22.3
400
United States
307.0
5990
India
1140.0
1140
China
1325.0
5300

7. METHANE Traps more 20 times the heat of Carbon Dioxide
Formed from breakdown of organic matter
Produced in the stomachs of cows and sheep as bacteria in their guts digest the cellulose in plants
Rice paddies, garbage tips, coal mines and natural gas fields all produce methane
Concentration of methane has also increased in the atmosphere
Permafrost-layers near the poles of rock/soil beneath the surface where the temp never rises above freezing.

8. Permafrost….
Vast areas of the Arctic- boggy wetlands-permafrost-lots of decomposing animals and plants-producing Methane
Permafrost traps the methane- Arctic stores billions of tonnes
Rising temps-boggy soil melts-methane released
Increased methane emissions may cause temps to rise further-melt more ice-release more methane- a positive feedback system

10. NITROUS OXIDE Traps more heat (300 times) than carbon dioxide
Again higher in atmosphere now than before industrial revolution
Produced in car exhausts
Industrial processes
Burning of forests and in the use of nitrogenous fertilisers
Homework:
Paragraph or two!! On the methane and nitrous oxide cycles-
How are the gases formed and broken down?
How readily are they formed?
How long does it take for them to be transformed into substances that are not green house gases

11. LOSS OF ICE WINTER-amount of ice in Antarctica doubles
Covers 19 million square kilometres -3 times the size of Australia
The extent and thickness of Ice-effects climate
Ice reflects more rays from the sun-cools Earth
Reduction of ice-means less cooling
When ice covers ocean water-acts as a blanket- less heat into atmosphere-remove the ice-more heat- hotter temps generally
ICE IS FRESH WATER- AS freezing locks out the salt!
This means salt is left in ocean-it gets more dense-the dense water sinks-moving into the deep currents that circle the earth
The Antarctic ocean is the major source of this “dense” water driving the global conveyor belt……..changes to the ice-changes the currents-changes the climate

12. Final points…… Shrinking Antarctica Carbon dioxide absorption:
Water on the surface of oceans absorbs carbon dioxide from atmosphere
As cold dense water sinks carbon dioxide carried with it
This “pumps” carbon dioxide out the atmosphere
Without it……more carbon dioxide left in the atmosphere
Shrinking Antarctica
Satellites are being used to measure the ice in Antarctica-to see if its shrinking
Results show –yes it is and rate is increasing
Watch polar bears special report Pearson's Reader
Pg 199 OZONE- human endeavour
Pg 201- freezing and density prac