Human influence on climate Power point 2 Global systems 6.3 Pearsons

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 2000-2009 was the warmest Increases in air and ocean temp Widespread melting of snow and ice Rising global sea levels

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

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

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…

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

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.

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

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

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

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