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Carbon Budget | A-level Geography | OCR, AQA, Edexcel

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  1. hi guys this is the second video on the carbon cycle and in this video we will be learning about the movement of carbon between stores understanding the effects
  2. of the changing carbon budget and answering an exam style question in the previous video we learned about the different stores of
  3. carbon as shown here in this diagram and just to give a recap we had the hydrosphere which included the oceans the lithosphere which was the crust and
  4. the upper mantle of the earth the biosphere which is our living factors such as plants and animals and then lastly our atmosphere as our last St so
  5. now we're going to look at how carbon has moved between these stores starting off by giving a brief overview to the different types of movements we have
  6. so we have movement through human processes such as the burning of fossil fuels we have the geological component which includes things like volcano nose
  7. and also the movement of rocks and the rock cycle photosynthesis which has to do with plants we have other biomass processes such as respiration and
  8. decomposition Oceanic carbon pumps combustion and volcanic activity I'm going to go through these in Greater detail now so don't worry if you don't
  9. understand what these are now I'm going to go over them all so before I go into these different types of movements
  10. it's good to understand what are carbon sinks and carbon stores and a carbon sink is a store that takes in more carbon than it releases
  11. and the opposite is a carbon store which releases more carbon than it takes in so for example if I draw a box here as our carbon
  12. STS the carbon store is going to be releasing more than it takes in it's shown by the fatter arrow and the opposite for a carbon sink which is
  13. taking in more than it's releasing so firstly we're going to look at the geological component of the movement of carbon and this is to do
  14. with the rock cycle so the rock cycle involves processes like the weathering of rock which is the breakdown of rock we have the burial of Rock subduction
  15. and this is what's happening at plate boundaries such as destructive plate boundaries where for example we have a tectonic plate being
  16. subducted underneath another plate and when it's subducted into the mantle which is beneath the crust it melts and becomes part of the mantle so that's
  17. what subduction is and then also at tectonic boundaries we also have volcanic activity where the mantle is coming up up and lava is being released
  18. onto the Earth's surface through volcanic activity so this is how carbon is moving back from the mantle into or onto the Earth's
  19. surface and it's also released as gases because volcanoes also emit Gases such as CO2 so it's also releasing CO2 back from the mantle into the atmosphere
  20. another part of the geological component of carbon movement is the formation of a limestone and this is through the process of carbon dioxide and water
  21. forming to form carbonic acid and this carbonic acid then reacts to form calcium carbonate also known as Limestone and this is a type of
  22. sedimentary rock that contains carbon as shown here and then as I was referring to before through the subd uction of plates
  23. at plate boundaries and where we have volcanic activity this Limestone and sedimentary rock that's been subducted is melted and
  24. then is released in volcanic activity it comes back up to the surface again and CO2 is then released back into the atmosphere through volcanic activity so
  25. that's just the process in Greater detail of how carbon is cycled through the geological component through reacting to form
  26. Limestone the Limestone then melted and then comes back up to the surface through volcanic eruptions and CO2 is released back into the atmosphere in
  27. clouds from volcanoes The Next Movement we have is through three interrelated processes which are photosynthesis respiration and
  28. decomposition so photosynthesis is the process that plants do to make their food and this food is normally a carbohydrate
  29. or otherwise known as glucose this is because plants don't eat other things they're called autotrof they make their own food using carbon dioxide water and
  30. sunlight and this process releases oxygen as well as forming glucose which is a sugar which the plant uses to grow and a similar process is
  31. respiration and carbon is moved in this because animals and plants do respiration to produce or release energy from
  32. carbohydrates such as here such as glucose and here it's combined with oxygen and then when this reacts together we get a release of energy
  33. water and also carbon dioxide so here carbon dioxide is being produced and during photosynthesis it is being consumed so they're almost like
  34. opposite processes of each other so that is carbon movement here but we also get carbon movement in decomposition and this is when organic matter such as dead
  35. plants and animals are decomposed by decomposers such as worms to form more stable forms of carbon that are put back into the soil of the earth and this
  36. recycles the carbon back into the soil as said here by decomposers such as little organisms like worms The Next Movement we have is through Oceanic
  37. carbon pumps and this is to do with Oceanic circul a represented by these arrows on this map here and the orange arrows represent the transfer of kind of
  38. warmer surface currents in the ocean whilst the blue arrows are those which are colder currents which travel at the Deep depths of the
  39. ocean and carbon is transported through these ocean conveyor belts because as this hot water circulates towards the holes it cools when it's in contact with
  40. the ice and this causes the water to cool and because cooler water is more dense it sinks to the bottom so here carbon dioxide is being transferred from
  41. the warmer surface currents to the deeper colder currents until they travel back round towards the equator and B by the Pacific where they rise again and
  42. they warm up so this is a transfer of carbon from the warmer layers to the lower cooler layers of the ocean then we have combustion and the process
  43. of combustion releases carbon in the form of carbon dioxide from organic material when it is burned and this process also releases water and energy
  44. so for example this is the combustion of fossil fuels which are burnt for example in cars petrol to release energy and this releases carbon dioxide we also
  45. have biomass combustion which is the burning of things like wood and plants and this is normally human induced but we can also get natural fires and here
  46. the carbon is being released from being stored within the wood um back into the atmosphere when the wood is burnt as I've mentioned before carbon
  47. dioxide is also released back into the atmosphere through volcanic eruptions and this is because CO2 is stored in the mantle of the earth and at volcanic
  48. eruptions the magma within the mantle is rising up through through the crust and CO2 is emitted by volcanoes back into the
  49. atmosphere so now I'm going to give you a few human activities which are causing the movement of carbon these include hydrocarbon extraction so this is
  50. extracting fossil fuels such as coal oil and gas from their stores deep in the lithosphere and using them for combustion the consumption of fuels for
  51. energy and this is releasing the carbon stored with within the fossil fuels back into the atmosphere as carbon dioxide also farming practices are big emitters
  52. of carbon dioxide and methane especially the beef industry as when cows digest they produce a lot of methane which is CH4 as you can see it's a carbon
  53. compound and this has serious implications for the greenhouse gas effect which we'll look at in the next video also
  54. deforestation deforestation a lot of the wood from deforestation is burnt in fires to clear the land um but also deforestation means
  55. that less carbon dioxide can be absorbed from the atmosphere by the trees during photosynthesis so this type of human activity has major impacts for the
  56. carbon cycle and also Urban growth where we get the development of cities we're obviously having greater amounts of Transport that requ ire fossil fuels so
  57. we get a greater consumption of fossil fuels overall for electricity and things like that so human activity has profound impacts on the carbon cycle as it
  58. changes the root of carbon and we also have a type of human process called carbon sequestration and this is where carbon dioxide is captured
  59. from the atmosphere and put into long-term storage and this is to stop it reaching the atmosphere because it has very damaging effects and this is to
  60. prevent the greenhouse gas effect or global warming and carbon in this case can be stored as carbon dioxide in what's called geological sequestration
  61. or terrestrial sequestration so geological sequestration is storing this carbon dioxide down deep within rocks and terrestrial is trying to store it
  62. within trees and plants as we just learned human activity was having major impacts on the carbon cycle and was releasing a lot of carbon
  63. dioxide into the atmosphere causing global warming due to the Greenhouse Effect and so now we're going to look at the effects of this changing carbon
  64. budget and firstly in relation to the land the impacts of the changing carbon budget are currently unclear because it hasn't been studied for long enough
  65. however there is distinct impact taking place on the ocean currently which are very visible the first one being sea level rise and this is because of the
  66. melting of sea ice as well as other factors which are causing sea levels to rise also attributed to Melting sea ice is that normally sea ice reflects a lot
  67. of solar radiation back into space which helps to cool the planet however with less sea ice there's obviously less reflection so
  68. this also acts to increase global warming but also sea level rise can be caused by thermal expansion and this is when the water is
  69. heating up and water expands when it's heated so the sea levels are actually increasing via volume as well as the amount of water being in the Seas this
  70. release of sea ice the fresh water trapped in sea ice is also reducing the salinity of the oceans also the warming of the oceans is allowing frighty panon
  71. to breed this makes the water almost appear cloudy and plants that live within seas and oceans and the surface level require photosynthesis to survive
  72. and therefore sunlight penetrating the water however if the water is kind of Cloudy because of the phylon sunlight can't get to the plants and therefore
  73. photosynthesis can't take place and it causes the plants to die also this changing carbon budget is cing ocean acidification now oceans are very
  74. slightly alkal and through the removal of carbonate ions from the oceans this is making the oceans more acidic and this has really
  75. significant impacts for Coral because Coral actually uses carbonate ions to form its shells and other animals as well as Coral do this as well and this
  76. is causing massive Coral wreath to die out shown here and this is a picture of dead coral now dead coral Coral is white in color whereas the live Coral has very
  77. vibrant colors to talk about sea level rise in a bit more detail this photo here shows an
  78. example of a beach and indicates where the water level will be by 2030 and 2050 and this is really significant and as I mentioned before sea level rise is both
  79. due to the melting of ice which increases the volume of water and also through thermal expansion through the heating up of the oceans causing the
  80. water to expand so the impact on the atmosphere is that with an increased amount of carbon dioxide in the atmosphere carbon
  81. dioxide is a greenhouse gas and it controls the Earth's temperature and carbon dioxide only accounts for 0.04% of the gases in the atmosphere but
  82. it's only this tiny amount that keeps the Earth as warm as it is today and with an even tinier amount added onto this this can cause significant warming
  83. effects which will potentially damage Dage the Earth's ecosystems and have other serious impacts and the reason this happens is due to radiative forcing
  84. and radiative forcing is the balance between of solar radiation coming into and heating the earth and its
  85. atmosphere so as you may know the Earth receives its heat from the Sun however CO2 and other greenhouse gases can act as an insulating kind of blanket around
  86. around the earth which keeps the Earth warmer so with more CO2 it's almost as if we have a bigger blanket so the Earth is going to warm up even more and this
  87. is because this said kind of blanket is absorbing the heat so if I draw an example of the earth here the increasing levels of CO2 and other greenhouse gases
  88. would cause more solar radiation from the Sun to be absorbed that is reflected back into space whilst if the Earth were to be
  89. cooling we would have more solar radiation being reflected rather than being absorbed so this is what radiative forcing is it's
  90. this balance between absorption and reflection and radiative balance would be where we had an equal amount of absorption and reflection however the
  91. global warming is occurring because we have too much being absorbed and too little reflected back and this is because carbon dioxide the molecule
  92. itself absorbs solar radiation rather than reflecting it and this is warming up the Earth so to finish off this section on the carbon
  93. cycle we're going to answer some exam style questions the first is a multiple choice question which asks which is a store of carbon a photosynthesis B
  94. biomass C respiration or D decomposition and the answer is B because B is a store of biomass whilst these others are processes of carbon
  95. movement the next question we're going to look at is a longer six marks question which asks the figure below shows the changing amounts of carbon
  96. dioxide production by source using the figure analyze the changes shown so this is the figure we have and it shows changing amounts of carbon dioxide by
  97. Source between 1900 and just beyond the year 2000 and it shows it for coal oil gas flaring and
  98. cement and it's measured in carbon dioxide emissions in gigatons of carbon per year and the graph is cumulative so this point here is the cumulative amount
  99. of carbon emissions for the year roughly of 2010 so as we can see back in 1900 the only emissions were coming from coal
  100. however has Tim is go on as we get to 1950 we start seeing the missions coming from oil gas flaring and cement but over time coal tends to be the main source
  101. for missions with oil kind of coming into second place being the second biggest emitter then gas then flaring and then
  102. cement however as we can see there is a dip here at about the 1970s 1980s so it will be good to comment on this little fluctuation we have here here as it is
  103. the only anomaly we have in the trends that we can see in this graph which is that the emissions from carbon are increasing as time goes on so now we're
  104. going to answer the question so in a previous video I mentioned that a good way to answer um a question using data is to use the format of opad which means
  105. overall pattern Place anomalies and data so we need to include all of these factors so beginning of this question we're going to State the overall Trends
  106. so I said overall the graph shows a steepening increase in carbon dioxide production from 1900 onwards coal Remains the largest source of CO2
  107. emissions across the last century whilst oil and gas emissions have significantly increased since 1950 emissions from cement and flaring have seen a minimal
  108. increase so this is giving the overall trends for the different types of Productions by Source now I'm going to specifically
  109. comment on the patterns and include some of the data so I've said CO2 production dramatically increased from around 1.5 gigatons of carbon per year in 1950 to
  110. 10 gatons of carbon per year in 2010 so yeah I'm using data really specifically this is something you really need to do this could be linked to the increase in
  111. global population and thus energy demand following World War I so here I've taken the data and I've analyzed it and then I'm going to talk about anom
  112. Aly which I mentioned when we looked at the graph was that little dip that we saw so I've said an anomaly is the decrease in emissions across all sources
  113. in the 1980s this could be the result of A disruption to the supply of fossil fuel sources which therefore sparked a sharp decrease in
  114. consumption so yet again I've provided my anomaly and then I've given a bit of analysis to it as well hi guys I hope you enjoyed the
  115. video If you're looking for an amazing a-level phography resource join me today in my series of engaging bite-size video tutorials see you soon and together
  116. let's make a-level geography a walk in the park

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