paper 2 - the atmosphere

Question 1

atmosphere of earth today

Answer 1

78% nitrogen
21% oxygen
1% other gases

Question 2

early earth and how carbon dioxide levels decreased

Answer 2

volcanoes released natural gases such as carbon dioxide. methane, ammonia and water vapour which formed the atmosphere

earth cooled and water vapour condensed forming the oceans

some of the carbon dioxide dissolved in the oceans to form a weak acid. this reacted with minerals in the sea to form precipitates. over time this formed sediments of carbonate rock on the sea bed

some of the carbon dioxide was used to make shells. when these died they formed the sedimentary rock limestone which also removed carbon dioxide from the atmosphere

Question 3

early earth atmosphere

Answer 3

98% carbon dioxide

Question 4

how oxygen levels increased

Answer 4

photosynthetic algae evolved

photosynthesis produced oxygen which entered the atmosphere

over the following billion years plants evolved. this increased the amount of oxygen in the atmosphere .

at some point the level of oxygen reached the point where animals could evolve

Question 5

fossil fuels

Answer 5

formed over millions of years

non renewable so they will eventually run out

all contain trapped carbon

Question 6

coal

Answer 6

is formed from the remains of trees

if these die in marshy wetlands then they dont decompose

this can be due to a lack of oxygen or acidic conditions

these both prevent bacteria from carrying out decomposition

over time the plant remains are covered with sediment and compressed

high temp and pressure creates coal

Question 7

crude oil

Answer 7

formed from plankton

when these die they settle in mud on the sea bed

if oxygen is not present they do not decompose

over time they are compressed by sediment

heat and pressure convert them into crude oil

Question 8

natural gas

Answer 8

mainly methane

often found near deposits of oil as it is formed by plankton similarly to oil

Question 9

types of greenhouse gases

Answer 9

water vapour

carbon dioxide

methane

Question 10

what greenhouse gases do in the atmosphere

Answer 10

energy from the sun travels to the earth as short wavelengths radiation

some of the shortlength radiation simply reflects back into space but most of it passes easily through the atmosphere

that is because short wavelength radiation doesnt interact strongly with the gas molecules in the atmosphere

the energy of the radiation is now absorbed when it reaches the surface of the earth

the surface of the earth now radiates the energy as long wave radiation

some of the long wave radiation interacts with the greenhouse gas molecules in the atmosphere - the energy is absorbed

because the energy is trapped in the atmosphere, this causes the temperature of the atmosphere to increase

Question 11

how levels of carbon dioxide are increasing

Answer 11

burning fossil fuels

normally carbon dioxide is absorbed by trees however because of deforestation and the burning of trees , more carbon dioxide is being released than absorbed

Question 12

how methane levels are increasing

Answer 12

released in agriculture

released when cattle pass wind

Question 13

how rising temperatures effect earth

Answer 13

increases melting of the polar ice caps which will increase sea levels

high sea levels leads to flooding in low land

more severe weather

change the distribution of animals and insect borne diseases

Question 14

carbon foot

Answer 14

the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or an event

Question 15

ways to reduce carbon dioxide emissions

Answer 15

insulating homes or turning down heating

using public transport as they release less carbon dioxide per passenger

switch to renewable sources of electricity

reduce electricity use at home

Question 16

ways to reduce methane emissions

Answer 16

eating less beef and dairy products as their is less cattle farming

trapping methane and using to produce electricity