C13- Earths Atmosphere

Scientists think the Earth was formed about 4.6 billion years ago

Formation of the Earth’s Atmosphere: 1. they believed that volcanoes released CO2, H2O, and N2, forming the Early atmosphere 2. As the water vapour cooled, it fell as rain, forming the oceans - ANOTHER THEORY: icy comets rain down on Earth, melting and adding to its water supplies 3. As Earth began to stabilise, it was mainly CO2 - there would N2, water vapour and traces of CH4 and NH3 ⟶ very little to no O2 4. This resembles the atmospheres of our closest planets (Mars + Venus) 5. scientists think the first organisms formed 3.4 billion years ago 6. Then, bacteria and other simple organisms like algae evolved 2.7 billion years ago 7. Algae photosynthesised to release O2 8. Over the next billion years, oxygen rose steadily and CO2 fell, as plants photosynthesised and algae and bacteria thrived in seas As plants evolved they successfully colonised the surface of the Earth 9. As the atmosphere became richer in oxygen, it became possible for the firs animal forms to evolve

Recently, CO2 levels have not changed much ⟶ this is due to the carbon cycle

Methane and ammonia found in the early atmosphere reacted with the oxygen to make CO2 and N2

30% of the energy reaching the Earth is reflected back into space

Earth cools down by emitting infrared radiation, but greenhouse gases absorb it

Sources of methane: decomposing waste of cattle, landfill sites, swamps and rice fields

CO2 sinks like tropical rainforests and oceans have become less effective due to human activity ⟶ deforestation by humans means less

global changing weather patterns could have the consequences of: 1. rising sea levels due to melting ice caps and expansion of warmer oceans ⟶ may cause floosing of low-lying land, increased coastal erosion and islands may disappear 2. increasingly common extreme weather events 3. changes in temperatures and amount, timing and distribution of rainfall - may impact food-producing capability of different regions 4. changes to distribution of wildlife species, with some becoming extinct - rapid changes will put ecosystems under stress

the carbon footprint of a product/service/event = the total amount of CO2 and other greenhouse gases emitted over its full life cycle

Carbon capture and storage - a solution to reduce CO2 emissions–> pump CO2 deep underground to be absorbed into porous rocks ⟶ this can also be done into old. redundant oil fuels

Ways the government is dealing with it: 1. taxing fossil fuels 2. taxing cars that burn lots of petrol/diesel 3.support the use of biofuels 4. there are policies that say when trees are felled, new ones must be planted in its place

Problems of reducing C footprint: 1. lifestyle changes - reducing the use of cars 2. cost 3. people disagree that climate change has consequences

Sulfur impurities in fossil fuels become sulfur dioxide after its burned

SO2 is the cause of acid rain which damages trees, and kills animals and plants in lakes - it also damages buildings made of limestone and metal

high temp inside an engine allows the normally reactive N2 gas in air to react with O2 making oxides of nitrogen ⟶ toxic + triggers people’s asthma

Crude oil and natural gas were formed from the remains of plankton deposited in muds on the seabed ⟶ it’s found deposited under layers of rock

30% of the energy reaching the Earth is reflected back into space