P2- Chemistry of the atmosphere Flashcards
How long ago was the earth said to be formed?
4.6 billion years ago
What is phase 1 of the evolution of the atmosphere?
1) Intense volcanic activity releasing gases that formed the earth’s early atmosphere
2) At the start, the atmosphere may be like Mars and Venus’ today, mainly CO2 with little to no O2
3) Volcanoes also produced nitrogen which built up in the atmosphere over time as well as water vapour and small amounts of methane and ammonia
What is phase 2 of the evolution of the atmosphere?
1) Water vapour condensed to form the oceans
2) CO2 dissolved in the water and carbonates were precipitated to produce sediments
3) This reduced the amount of CO2 in the atmosphere
What is phase 3 of the evolution of the atmosphere? (oxygen increase)
1) Algae and green plants produced O2 that is now in the atmosphere by photosynthesis
2) Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere
3) Over the next billion years plants evolved and the % oxygen gradually increased to a level that enabled animals to evolve
3 ways carbon dioxide decreased in the evolution of the atmosphere
1) Algae and plants decreased the % CO2 in the atmosphere by photosynthesis
2) The formation of sedimentary rocks that contain
carbon (e.g. limestone and coal)
3) the production of fossil fuels from the remains of dead plants and animals when they decayed
% of nitrogen in the atmosphere today
80
% of oxygen in the atmosphere today
20
What are the 3 main gases that make up about 1% of the atmosphere today
Carbon dioxide
Methane
Water vapour
What are carbon dioxide, methane and water vapour all examples of?
Greenhouse gases
What do greenhouse gases do?
Act like an insulating layer in the Earth’s atmosphere to allow the earth to be warm enough to support life
What don’t greenhouse gases absorb?
The incoming short wavelength radiation from the sun
What do greenhouse gases absorb?
The long wavelength radiation that gets reflected back off the earth.
What happens after greenhouse gases absorb the long wavelength radiation that gets reflected back off the earth?
They re-radiate it in all directions, including back to the earth
Why are greenhouse gases causing global warming?
The long wavelength radiation that the greenhouse gases absorb and re radiate back on to the earth is thermal radiation, so it results in the warming of the surface of the earth, otherwise known as the greenhouse effect
4 examples of human activity that affect the amount of greenhouses gases in the earth’s atmosphere
1) Deforestation (less CO2 removed via photosynthesis)
2) Burning fossil fuels (carbon gets released)
3) Agriculture (farm animals produce methane)
4) Waste from landfill sites and agriculture means more CO2 and methane released by decomposition of waste
What do scientists agree will cause global warming and therefore climate change?
Human activity
Why are scientists agreeing that human activity is causing extra CO2 and climate change reliable?
It has been peer-reviewed
Why is it hard to fully understand the earth’s climate? What does this lead to?
It is so complex and there are so many variables so it is hard to model. This leads to oversimplified models, speculation and opinion which could be biased or only use some info
4 examples of the dangerous consequences of climate change?
1) Polar ice caps melting causing a rise in sea levels, increased flooding in coastal areas and coastal erosion
2) Changes in rainfall patterns (too much or little water which is bad for farming and crops)
3) Frequency and severity of storms might increase
4) Changes in temp and amount of water in a habitat may affect wild species, leading to differences in their distribution
What are carbon footprints?
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product (toaster), service (bus) or event (olympics).
How can carbon footprint be reduced?
Reducing emissions of carbon dioxide and methane
4 ways to reduce carbon footprint
1) Renewable energy sources/nuclear energy instead of fossil fuels
2) More efficient processes to conserve energy and cut waste
3) Govt tax companies/people based on amount of GG they emit
4) Govt capping GG emissions that companies make
4 reasons why reducing emissions is difficult
1) Still a lot of work to be done on alternative technologies
2) Govt are worried these changes will impact economic growth of communities (bad for people’s wellbeing especially in developing countries)
3) Hard to make international agreements as not everyone is on board
4) Individuals in developed countries might not want to or aren’t educated enough as to why change is necessary
What do fossil fuels contain?
Hydrocarbons
