Chemistry of the Atmosphere Flashcards
What are the proportions of gases in the air?
80% Nitrogen
20% Oxygen
small proportion of other gases: Carbon dioxide, water vapour, noble gases
Why is evidence for the early atmosphere and its formation limited?
Due to the time scale of 4.6 billions years
What is a theory of the formation of the early atmosphere?
During first billion years of Earth’s existence
- intense volcanic activity, released gases forming the early atmosphere
- released water vapour-> condensing into oceans
- volcanoes produced nitrogen: gradually built up in atmosphere, also small proportions of methane and ammonia
What was the Earth’s atmosphere like during the beginning of the period of the atmosphere forming?
Earth’s atmosphere similar to current Mars or Venus atmosphere (mainly CO2, little oxygen)
During the formation of the atmosphere, what happened when oceans formed?
- Carbon dioxide dissolved into the water
- ## Carbonates precipitated-> produced sediments, reducing amount of CO2 in atmosphere
What is the photosynthesis equation?
6CO2 + 6H2O -> C6H12O6 + 6O2
produced by algea and plants during the formation of the early atmosphere-> increasing oxygen, decreasing carbon dioxide
How did the percentage of oxygen in the atmosphere gradually increase?
- first produced oxygen around 2.7 billion years ago-> began appearing in atmosphere
- over next billion years: plants evolved, % of oxygen increased
- eventually enabled animals to evolve
How did levels of Carbon dioxide decrease in the early atmosphere?
- algea and plants due to photosynthesis
- formation of sedimentary rocks and fossil fuels that contain carbon
- dissolved into oceans-> reacted to form carbon precipitates that formed sediments on the seabed
What are Greenhouse Gases and what do they do?
Maintain temperatures in the atmosphere on Earth to support life
- Water vapour, Carbon dioxide, Methane
How are fossil fuels formed?
Crude oil and natural gas- deposits of plankton, form thick reservoirs under the seabed
Coal- sedimentary rock made from thick plant deposits
Limestone- sedimentary rock, calcium carbonate deposits from shells and skeletons of marine organisms
How does plants, plankton and marine animals dying lock carbon away?
- the organisms die and sink to the seabed
- then get buried under layers of sediment
- become compressed and form sedimentary rocks, oil and gas over millions of years
- trapping carbon within- reducing CO2 levels in the atmosphere
What is the evidence from volcanoes for the evolution of the early atmosphere?
- Gases released by volcanoes today are similar to volcanoes that erupted billions of years ago
- gives evidence as to what gases were present in the early atmosphere
What is the evidence from other planets for the evolution of the early atmosphere?
- Atmosphere of planets where there is no life (Mars, Venus etc)
- Can be used to predict what atmosphere might have been like before life evolved.
What is the evidence from rocks for the evolution of the early atmosphere?
- Certain rocks called ‘Red beds’ contain lots of iron oxide.
- Can only form when there is enough oxygen in the atmosphere to react with iron
- Age of red beds can be used to predict at which point oxygen levels reached a particular level in the atmosphere.
What is the evidence from living things for the evolution of the early atmosphere?
- Some simple organisms (ie early bacteria), DONT rely on reactions involving oxygen to release energy
- Use other gases (ie carbon dioxide)
- Fossils of bacteria have been found which are older than fossils of creatures that depend on oxygen
- Implies life first evolved without need for oxygen, so not much in the early atmosphere
What is the Greenhouse effect?
- The sun emits short wavelength radiation, which passes through the earth’s atmosphere, and isn’t absorbed by greenhouse gases
- Short wavelength radiation reaches the Earth’s surface, is absorbed, then reemitted as long wavelength radiation
- This radiation is absorbed by greenhouse gases in the atmosphere
- Then the gases re-radiate in all directions, including towards earth
- Longwave radiation= thermal radiation-> results in the warming of the surface of the earth (the greenhouse effect)
How is more carbon being added to the environment and less being removed?
- human population is rapidly increases-> becoming more industrialised
- burning more fossil fuels-> releasing carbon
- cutting down forests-> no longer absorbing carbon for photosynthesis
How has the global population increases led to the increase of carbon in the atmosphere?
- more food needs to be produced-> methane levels rising (ie cows, paddy fields for rice)
- more waste-> more landfill, which can break down and release more CO2 and METHANE
What do most scientists agree on about the effect of extra greenhouse gases in the atmosphere?
- extra greenhouse gases in the atmosphere due to human activity
- cause an increase in temperature-> will lead to climate change
this evidence has been peer reviewed, so is reliable
Why is it hard to understand the earth’s climate? What has this led to?
- complex and many variables
- hard to make a model that isn’t over simplified
- speculation on climate change and its impact-> speculation happens in the media (biased or misinformed storied)
What are some consequences of climate change?
- Increase in global temperature-> polar ice cap and glaciers melting, causing a rise in sea levels, increasing flooding in coastal areas and coastal erosion
- Changes in rainfall patterns (timing, amount, distribution)-> may cause some regions to get too much or too little water
Along with changes temp-> can affect regions ability to produce foods - Increase in frequency and severity of storms
- Changes in temperature and amount of water available in a habitat-> affects wild species, leading to differences in distribution
Why is it important that scientists communicate new evidence to a wide range of people?
- climate change can affect everyone on the planet
- people can be informed, then they can decide how to act in response to climate change
What do climate change policy makers need to consider?
How many people might be affected-> some changes affect fewer people than others (living inland= unlikely to be affected by coastal erosion) OR can affect masses (area important for global food production, if crops dont grow-> millions of people affected)
What impact the change could have->
- Short term= severe blizzards disrupt transport links BUT snow melts
- Long term= rising sea levels could permanently flood towns or cities close to the sea
What are Carbon Footprints?
measure of the amount of carbon dioxide and other greenhouse gases released over a full life cycle.
Why is measuring a carbon footprint difficult?
Many different factors to consider
- however can make a rough calculation
What are methods to reduce carbon footprints?
- use renewable energy sources or nuclear sources (instead of burning fossil fuels)
- develop more efficient processes that use less energy (less fossil fuels need to be burnt)
Processes that produce less waste= less greenhouse gas emissions (less decomposing into methane gas)
How can the government encourage people to reduce emissions?
- tax companies or individuals based on amount of greenhouse gases emitted
- place cap on amount of greenhouse gases a company could make + sell licenses for emissions up to the cap
- Bills businesses pay for electricity, natural gas and coal are taxed-> encourages to use more energy efficient processes
- Some businesses have to pay tax on amount of waste sent to landfill (UK)
How can technology be used to reduce carbon footprints?
- technology that captures CO2 produced by burning fossil fuels BEFORE its released into the atmosphere
- then can be stored deep underground in cracks in rock (old oil wells etc)
= CARBON CAPTURE AND STORAGE
What are issues with reducing carbon footprints?
- Governments, using caps and taxed on emissions could reduce economic growth of communities (especially for developing countries)
- Hard to make international agreements to reduce carbon emissions
- Reducing carbon footprints= costly, less profits for businesses
- People making changes (walking and cycling instead of car) is hard to enforce.
Lack of knowledge on the subject or interest means they won’t change
