C9 Flashcards
How long have the proportions of gases in the atmosphere been the same for and what are they?
200 million years
4/5 nitrogen =80% (approximately)
1/5 oxygen=20%(approx)
small proprtions of other gases eg CO2, water vapour and noble gases.
Why is evidence for the early atmosphere limited?
Because theories about how the atmosphere was formed have changed and developed over 4.6 billion years.
What is stage 1 of the evolution of the atmosphere theory?
There was instense volcanic activity that realeses lots of gases which made earths early atmosphere.
Why was the start of phase 1 of the earths early atmosphere similar to Mars and Venus?
Becacuse it consisted of mainly carbon dioxide with little oxygen.
What did volcanoes also produce?
Volcanoes also produced nitrogen, which built up in the atmosphere over time, as well as water vapour and small amounts of methane and ammonia.
How were seas and oceans formed?
Water vapour in the atmosphere condensed to make the oceans.
How are levels of carbon dioxide in the atmosphere reduced (oceans)?
When oceans formed carbon dioxide dissolved in the water and carbonates were precipitated producing sediments (limetsone- a calcium carbonate made of shells and skeletons of marine animals).
How did algae and plants decrease the percentage of carbon dioxide?
By evolving and carrying out photosynthesis
How else was carbon dioxide decreased?
By the formation of sedimentary rocks and fossil fuels (coal,crude oil, natural gas which all contain carbon).
How are crude oil, coal and natural gas formed?
When plants,plankton and marine animals die, they fall to the seabed and get buried by layers of sediment. Over millions of years, they become compressed to form sedimentary rocks(coal), crude oil and natural gas- trapping the carbon within them.
What is the differences between how crude oil and natural gas is formed and how coal is formed?
Crude oil and natural gas formed of deposits of plankton and form reservoirs under the seabed when they get trapped in rocks.
Coal is a sedimentary rock made from thick plant deposits.
How did the levels of oxygen increase and when?
Algae first produced oxygen 2.7 billion years ago (photosynthesis). Over the next billions of years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.
What do greenhouse gases do?
Greenhouse gases in the atmosphere maintain temperatures on Earth high enough to support life.
Name 3 greenhouse gases?
Water vapour
Carbon dioxide
Methane
Explain the greenhouse effect?
1)The sun gives out short wavelengh radiation which is re-emitted back by the earth as long wavelengh radiation.
3) The long wavelengh radiation is absorbed by the greenhouse gases in the atmosphere.
4)Greenhouse gases re-radiate the heat in all directions including back to earth causing the temperature to rise.
Which human activities increase the amounts of the greenhouse gases carbon dioxide and methane?
CO2- deforestation (less tress, less co2 is removed from the atmosphere via photosynthesis)
CO2- Burning fossil fuels (carbon that was locked up in these fuels is released as CO2)
Methane- Cattle and rice farming
Methane + CO2- More Landfill sites and waste from agriculture- more CO2 and methane released by decomposition of waste.
What do scientists think global climate change will be the result of?
Based on peer-review (reliable) evidence, many scientists believe that human activities will cause the temperature of the earths atmosphere to increase at the surface and result in climate change.
What has not being able to fully understand the Earths climate led to?
It leads to simplified models, speculation and opinions presented in the media that may be based on only parts of the evidence and be biased.
What is climate change a cause of?
An increase in average global temperature
What are 4 effects of global climate change?
-polar ice caps melting
-changes in rainfall patterns
-frequency + severity of storms may increase
- changes in temp+amount of water- leading to differences in wild species distribution.
What can polar ice caps melting lead to?
Increase in global temperature could lead to polar ice caps melting
-causing a rise in sea levels
-increased flooding in coastal areas
-coastal erosion
What can changes to rainfall patterns lead to?
May cause some regions to get too much/little rainfall. This along changes in temperature, may affect the ability of certain regions to produce food.
What is a carbon footprint?
The carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
How can carbon footprint be reduced?
The carbon footprint can be reduced by reducing emissions of carbon dioxide and methane.
What can be done to reduce emissions of carbon dioxide and methane?
-Renewable energy sources or nuclear energy could be used instead of fossil fuels.
-Using more efficient processes to conserve energy and cut waste (waste decomposes to release methane- this will reduce methane emissions).
-Governments could tax companies or individuals based on the amount of carbon dioxide they emit.
-Government can put a cap on emissions of all greenhouse gases that companies make -sell licenses for emissions up to that cap.
-Technology that captures CO2 produced by buring fossil fuels before its releases into the atmosphere (stored underground).
Why are actions to making reductions in using carbon dioxide and methane limited?
-Work needs to be done on alternative technologies that result in lower CO2 emissions.
-Could impact on the economic growth of countries (bad for ppls well-being).
-Not all countries want to make international agreements to reduce emissions.
-Hard for ppl to make changes to lifestyle (not enough education to why the changes are necessary and how to make them).
What is the combustion of fuels a major source of?
Its a major source of atmospheric pollutants.
What do most fossil fuels (icluding coal) contain?
Most fuels contain carbon and/or hydrogen and may also contain sulfur.
What happens during combustion to fossil fuels?
During combustion the carbon and hydrogen in these compounds are oxidised so carbon dioxide and water vapour are released into the atmosphere.
When does all the fuel burn?
When theres plenty of oxygen-complete combustion.
What happens in incomplete combustion of fuels and what is released?
This happens if there isnt enough oxygen, some of the fuel doesnt burn. Solid particles (particulates) of soot (carbon) and unburned fuel are released and carbon monoxide and carbon dioxide can be produced.
What problems can particulates cause?
If inhaled they can get stuck in the lungs and cause damage leading to respiratory problems.
Bad for the environment- They (or clouds they produce) reflect sunlight back into space, less light reaches the earth- causing global dimming.
What problems can carbon monoxide cause (toxic gas)?
It can stop your blood carrying oxygen around the body by binding to the haemoglobin in your blood which can lead to fainting, coma or death.
Its colourless and odourless so hard to detect- makes it even more dangerous.
How is sulfur dioxide released?
During the combustion of fossil fuels, eg coal, that contains sulfur impurities- the sulfur becomes oxidised.
How are nitrogen oxides created?
Nitrogen oxidies are created from a reaction between the nitrogen and oxygen in the air, caused by heat of the burning.
Why is it dangerous for sulfur dioxide and nitrogen oxide to mix?
When these gases mix with clouds they form dilute sulfuric/nitric acid which then falls as acid rain which kills plants and damges building and statues and makes metals corrode.
They can also cause respiratory problems when breathed in.
