C11 Flashcards
How much of nitrogen has been in our atmosphere over the last 200 million years
About 80% nitrogen
How much of oxygen has been in our atmosphere over the last 200 million years
About 20% oxygen
Which gases in the atmosphere are there small proportions of?
Carbon dioxide
Water vapour
Noble fases
Why are we not certain what the Earth’s early atmosphere was like?
The Earth is 4.6 billion years old, and there’s a lack of evidence throughout this long timescale.
What five changes occurred at the early atmosphere
Oxygen increased
Carbon dioxide decreased
Methane decreased
Ammonia decreased
Nitrogen increased
How oxygen increased in the atmosphere
Algae first produced oxygen about 2.7 million years ago by photosynthesis, and this appeared in the atmosphere.
Over the next billion years,plants evolved and the percentage of oxygen increased gradually to a level for animals to evolve
How carbon dioxide decreased in the atmosphere
CO2 was used up in processes like photosynthesis and the formation of sedimentary rocks/fossil fuels
Examples of sedimentary rocks(which use up CO2)
Limestone and coal
Formation of limestone
CO2 dissolved in oceans to form carbonate ions.
Carbonate ions used by marine organisms to build shells/skeletons out of calcium carbonate.
Upon death, the shells sank.
Shells/skeletons buried/compressed over millions of years to form sedimentary rock
Formation of coal
1) Plants and trees used CO2 during photosynthesis to build their tissues.
2)Plants and trees died in swamps and decayed in the absence of oxygen.
3)They were compressed over millions of years to form coal.
How crude oil and natural gas formed
1) Crude oil and natural gas both formed from an ancient biomass(plankton) buried in mud.
2) The remains of the plankton were covered by more sediment.
3) They were compressed over millions of years to form crude oil and natural gas.
4) Temperature during burial determines whether oil/gas are produced.
How has the carbon cycle affected CO2 levels?
The amount of CO2 in the atmosphere has stayed the same for the last 200 million years because of the carbon cycle.
How methane decreased in the atmosphere
Methane reacted with the oxygen that was being produced by photosynthesis
How ammonia decreased in the atmosphere
Ammonia reacted with the oxygen that was being produced by photosynthesis
How nitrogen increased in the atmosphere
Nitrogen gas is very unreactive so was able to build up in the atmosphere
What are the main greenhouse gases in the atmosphere
Water
Carbon dioxide
Methane
How do greenhouses work?
1) Greenhouses allow short-wavelength radiation from the
Sun through
2) The glass absorbs the long-wavelength radiation emitted from inside the greenhouse.
3) This keeps the plants inside the greenhouse warm
Fossil fuels using up CO2
Crude oil and natural gas
The Greenhouse effect
1) The Sun emits short-wavelength radiation which warms the Earth, but the Earth loses this heat by emitting long-wavelength radiation.
2)Greenhouse gases absorb some of this long-wavelength radiation.
3) They re-radiate this thermal radiation in all directions, including back to the Earth. This warms the atmosphere.
How’s methane produced?
Cattle is reared for humans producing methanes.
The decay of waste in landfill by microrganisms produces methane
What do most scientists believe human activities will cause?
The temperature of the Earth’s atmosphere to increase at the surface and this will cause global climate change
Evidence that global warming will cause climate to change
Other scientists(peers) check evidence before it’s published.
Scientists collecting and analysing data(evidence).
How does modelling climate change work?
1) Scientist has hypothesis
2)Scientist collects data and writes computer program = model
3) Model predicts future
Challenges with modelling climate change
Scientists have a duty to report any uncertainties in their models.
Non-scientists with a vested interest
(individual’s own stake in an investment or project) may present a biased opinion based on only part of the evidence in the media.
Carbon footprint
Total amount of CO2 and other greenhouse gases emitted over the full life cycle of a product, service or event
What is the carbon footprint of a product, service or event reduced by
Reducing emissions of carbon dioxide and methane
How does sending less waste to landfill by recycling more reduce methane?
Less waste breaks down in the landfill site to release greenhouse gases
How does charging more tax on polluting vehicles reduce CO2?
This discourages people from driving cars which produce CO2 when hydrocarbon fuels are burned in the engine
Methods of reducing methane
Eating less beef
Sending less waste to landfill by recycling more
Methods of reducing CO2
Charging more tax on polluting vehicles
Using biofuels
Capturing CO2 produced in power stations and storing it in rocks
Disadvantages of carbon capture and storage
Expensive technology
Fossil fuels have previously led to economic growth - appealing for developing countries
Difficult to get all nations in thr world to agree to make the major changes needed
Atmospheric pollutants
Carbon dioxide
Water vapour
Carbon monoxide
Sulfur dioxide
Nitrogen oxides
Solid particulates
How are carbon dioxide/water vapour produced
By complete combustion of hydrocarbon fuels
How is carbon monoxide produced
By incomplete combustion of hydrocarbon fuels
Effects of carbon monoxide
Toxic
Colourless and odourless
Binds to haemoglobin in red blood cells in place of oxygen,less oxygen=less respiration = health problems
How is sulfur dioxide produced
Sulfur reacts with oxygen during combustion to produce sulfur dioxide
Effects of sulfur dioxide
Respiratory problems
Acid rain - kills wildlife and damages buildings
Solutions to reduce the impact of sulfur dioxide
Sulfur impurities can be removed from a fuel before the fuel is burnt
Solutions to nitrogen oxides
Using catalytic converters in cars
Problems with unburned fuels
Waste fuel and some fuels may be greenhouse gases
Solutions for unburned fuels
Engine is well tuned
Problems with water
None - H2O is maintained naturally
Solution for carbon monoxide
A good supply of air
Solution to carbon soot/particulates
Good supply of air when fuel’s burnt
How are nitrogen oxides produced
The high temperature of the engine causes the nitrogen in the air to react with the oxygen in the air.
Effects of nitrogen oxides
Respiratory problems
Acid rain - kills wildlife and damages buildings
How are particulates formed?
If diesel doesn’t burn completely(incomplete combustion), then tiny solid particles of carbon soot and unburnt fuel are produced.These are called particulates
Effects of solid particulates and unburned fuel/soot
Particulates cause health problems e.g. lung damage and global dimming: where
particulates in the upper atmosphere reflect sunlight back into space - less reaches the Earth.
How human activities increase amount of methane in atmosphere
Creating waste - methane released by decomposition of waste.
Increased agriculture - farm animals produce methane through digestive processes
First creature to photosynthesis
Cyanobacteria, about 2.7 billion years ago
Actions to reduce carbon footprint
Increased use of alternative energy supplies
Energy conservation
Carbon capture and storage
Carbon taxes and licences
Carbon off-setting including through tree planting
Carbon neutrality - zero net release
Advantages of complete combustion
More heat per gram of fuel
released
Less soot made
Poisonosu carbon monoxide not produced
Problems of reducing carbon footprint
Scientific disagreement over causes and consequences of global climate change
Lack of public information and education
Lifestyle changes
Econ9mic consideration
How is carbon capture storage carried out?
Carbon dioxide(produced by power stations/factories) is trapped:
Stored underground e.g. in old oil fields
Turned into liquid or solid
Reacted with other chemical
Internal combustion engines
Increases the amount of carbon dioxide in the atmosphere, because:
Burning/combustion of fossil fuels and because of (locked up) carbon oxygen used
Reactions in sea water
Decrease the amount of carbon dioxide in the atmosphere, because:
Produces calcium carbonate which is insoluble.
Produces calcium hydrogencarbonate which is soluble.
Photosynthesis occurs which produces oxygen
What does a catalytic convertor do?
It converts carbon monoxide into carbon dioxide
Why should atmospheric pollution be controlled?
Idea air quality is maintained, can reduce or prevent harm to living organisms, can control/reduce smog and protect buildings/metals.
Problems of atmospheric pollution
Air pollution travels everywhere, affecting the environment and people’s health(can trigger asthma), can cause greenhouse gases and photochemical smog
