Energy Education

Anthropogenic carbon emissions: Difference between revisions

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[[Category:Done 2016-01-15]]  
[[Category:Done 2026-07-01]]  
[[File:carbonextraction.png|400px|thumb|Figure 1. Carbon is trapped underground in reservoirs, extracted, and used by humans through the process of combustion. This causes a release of carbon dioxide (and other carbon compounds) which would otherwise not reach the atmosphere, ocean, or soil.<ref>''Created internally by a member of the Energy Education team''.</ref>]]
[[File:carbonextraction.png|400px|thumb|Figure 1. Carbon is trapped underground in reservoirs, extracted, and used by humans through the process of combustion. This causes a release of carbon dioxide (and other carbon compounds) which would otherwise not reach the atmosphere, ocean, or soil.<ref>''Created internally by a member of the Energy Education team''.</ref>]]
<onlyinclude>'''Anthropogenic carbon emissions''' are the [[emissions]] of various forms [[carbon]] - the most concerning being [[carbon dioxide]] - associated with human activities. These activities include the [[combustion|burning]] of [[fossil fuel]]s, [[deforestation]], land use changes, livestock, fertilization, etc., that result in a net increase in emissions.<ref name=IPCC_SREX>IPCC, 2012: Glossary of terms. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 555-564.</ref></onlyinclude>  
<onlyinclude>'''Anthropogenic carbon emissions''' are any [[emissions]] of [[carbon]] that are associated with human activities. The two most concerning forms are [[carbon dioxide]] and [[methane]]. Examples of human activities which emit carbon include the [[combustion|burning]] of [[fossil fuel]]s, [[deforestation]], changes in land use, livestock, fertilization, and anything else that results in a net increase in emissions.<ref name=IPCC_SREX>IPCC, 2012: Glossary of terms. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 555-564.</ref></onlyinclude>  


==Increasing Carbon Levels==
==Increasing Carbon Levels==
A major concern is the emission of [[carbon dioxide]] (CO<sub>2</sub>) - a type of greenhouse gas - which contributes to [[global warming]] and [[ocean acidification]]. CO<sub>2</sub> and other compounds of [[carbon]] are exchanged throughout [[carbon pool]]s in the global '''[[carbon cycle]]'''. The [[natural carbon cycle]] is kept in a near perfect balance, however human emissions are input into the cycle which cause a net increase in concentrations of carbon in the [[atmosphere]], soil, and [[ocean]]s, as seen in Figure 1.<ref name=cc>M. Melieres and C. Marechal, "Warming in the 20th century," in ''Climate Change: Past, Present and Future'' 1st ed., U.K.: Wiley, 2015, ch.29, sec.3, pp. 310-312</ref>  
A major concern is the emission of [[carbon dioxide]] (CO<sub>2</sub>) - a type of greenhouse gas - which contributes to [[global warming]] and [[ocean acidification]]. CO<sub>2</sub> and other compounds of [[carbon]] are exchanged throughout [[carbon pool]]s in the global '''[[carbon cycle]]'''. The [[natural carbon cycle]] is kept in a near perfect balance. However, human emissions are constantly added into the cycle which causes a net increase in concentrations of carbon in the [[atmosphere]], soil, and [[ocean]]s, as seen in Figure 1.<ref name=cc>M. Melieres and C. Marechal, "Warming in the 20th century," in ''Climate Change: Past, Present and Future'' 1st ed., U.K.: Wiley, 2015, ch.29, sec.3, pp. 310-312</ref>  


[[Methane]] (CH<sub>4</sub>), [[carbon monoxide]], and [[particulate matter|black carbon]] are all present in the atmosphere, and each have varying [[greenhouse effect|effects]] on the planet. The amount of each of these in the atmosphere has been increasing rapidly: the amount of carbon dioxide in the atmosphere has increased by about 40% since the industrial era, and methane by about 150%.<ref name=cc/> These levels had been relatively stable for around 10 thousand years prior to this.<ref>IPCC, ''The Natural Carbon Cycle'' [Online], Available: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3.html</ref>
[[Methane]] (CH<sub>4</sub>), [[carbon monoxide]], and [[particulate matter|black carbon]] are all present in the atmosphere, and each have varying [[greenhouse effect|effects]] on the planet. The amount of each of these in the atmosphere has been increasing rapidly: the amount of carbon dioxide in the atmosphere has increased by about 40% since the industrial era, and methane by about 150%.<ref name=cc/> These levels had been relatively stable for around 10 thousand years prior to this.<ref>IPCC, ''The Natural Carbon Cycle'' [Online], Available: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3.html</ref>
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There are many scientific methods that allow for the measurements of human emissions, two of which will be talked about here:
There are many scientific methods that allow for the measurements of human emissions, two of which will be talked about here:


#The '''first method''' is the investigation of carbon-14 (<sup>14</sup>C), a [[radioactive]] [[isotope]] of carbon. <sup>14</sup>C is found naturally in atmospheric CO<sub>2</sub>, however it is not present in fossil fuels that humans extract from underground. This is because fossil fuels were [[oil formation|formed millions of years ago]], far longer than the [[half-life]] of <sup>14</sup>C (t<sub>1/2</sub> = 5730 years), meaning that all of the <sup>14</sup>C has [[radioactive decay|decayed]] away.<ref name=cc/> This means that carbon emitted by these fuels does not contain any <sup>14</sup>C. By measuring levels of <sup>14</sup>C and CO<sub>2</sub> over time, it is found that the vast majority of excess CO<sub>2</sub> does not contain <sup>14</sup>C and therefore can be attributed to fossil fuels.  
#The '''first method''' is the investigation of carbon-14 (<sup>14</sup>C), a [[radioactive]] [[isotope]] of carbon. <sup>14</sup>C is found naturally in atmospheric CO<sub>2</sub>, however it is not present in fossil fuels that humans extract from underground. This is because fossil fuels were [[oil formation|formed millions of years ago]], far longer than the [[half life]] of <sup>14</sup>C (t<sub>1/2</sub> = 5730 years), meaning that all of the <sup>14</sup>C has [[radioactive decay|decayed]] away.<ref name=cc/> This means that carbon emitted by these fuels does not contain any <sup>14</sup>C. By measuring levels of <sup>14</sup>C and CO<sub>2</sub> over time, it is found that the vast majority of excess CO<sub>2</sub> does not contain <sup>14</sup>C and therefore can be attributed to fossil fuels.  
#The '''second method''' relates to changes in [[atmospheric oxygen]] levels. It is employed in order to determine whether this excess CO<sub>2</sub> is indeed from human fossil fuels, or if it is instead from the likes of volcanic eruptions. This method works off of basic [[hydrocarbon combustion]] knowledge - when a fossil fuel is burned, its [[hydrocarbon]]s consume oxygen in order to give off [[energy]], along with [[water vapour]] and carbon dioxide. Therefore oxygen levels are expected to decrease when humans burn fossils fuels, and when measuring levels over time it is found that they ''do'', the amounts of which are in accordance with measured carbon dioxide levels. If the emissions were instead dominantly from volcanoes, there would be no measured decrease in atmospheric oxygen levels.<Ref name=cc/>  
#The '''second method''' relates to changes in [[atmospheric oxygen]] levels. It is employed in order to determine whether this excess CO<sub>2</sub> is indeed from human fossil fuels, or if it is instead from the likes of volcanic eruptions. This method works off of basic [[hydrocarbon combustion]] knowledge - when a fossil fuel is burned, its [[hydrocarbon]]s consume oxygen in order to give off [[energy]], along with [[water vapour]] and carbon dioxide. Therefore oxygen levels are expected to decrease when humans burn fossils fuels, and when measuring levels over time it is found that they ''do'', the amounts of which are in accordance with measured carbon dioxide levels. If the emissions were instead dominantly from volcanoes, there would be no measured decrease in atmospheric oxygen levels.<Ref name=cc/>  


==Where do these Emissions Go?==
==Where do these Emissions Go?==
The net destination of emissions from human activities is seen in Figure 2 below. This figure shows the flow of anthropogenic carbon from its emission (dominantly from fossil fuel combustion), to where it ends up, in Earth's major [[carbon pool]]s. The units are in [[gigatonne]]s of carbon per year, portraying the rate of carbon transfer. Remember, a gigatonne is an immense amount of material - equivalent to the [[mass]] of 200 million elephants!
The net destination of emissions from human activities is seen in Figure 2 below. This figure shows the flow of anthropogenic carbon from its emission (dominantly from fossil fuel combustion), to the atmosphere. Once these greenhouse gasses have been emitted, natural processes move these around and they settle in different [[carbon pool]]s: the atmosphere, the ocean and the land. Over the past few decades the amount that's ending up in the different carbon pools is shifting more heavily towards the atmosphere.


[[File:humancarbon.png|750px|thumb|center|Figure 2. The net emissions from human activity, and the amount that ends up in Earth's three broad carbon pools. Amounts are measured in [[gigatonne]]s of carbon.<ref>Information from Ref.3, images from Wikimedia Commons.</ref>]]
[[File:Anthropogenic_carbon_emission_Sankey.png|820px|thumb|center|Figure 2. The net emissions from human activity go into the atmosphere, and natural processes distribute those GHGs into three broad carbon pools. With roughly half staying in the atmosphere and the other half being somewhat evenly split between the land and the ocean.<ref name=cc/> <ref> Images taken from https://www.pxfuel.com/en/free-photo-jdbya
https://commons.wikimedia.org/wiki/File:Stenshuvud_forrest.jpg</ref>]]
 
==Where do these Emissions Come from?==
The [[Sankey diagram]] below shows where the world's GHG emissions come from. As seen in figure 3, the majority of the emissions come from natural gas, oil and coal that are used for the world's primary energy. While methane and other greenhouse gasses are a problem, carbon dioxide is the biggest contributor to changing the world's climate.
[[File:Sankey world-greenhouse-gas-emissions-2023.png|820px|thumb|center|Figure 3. Roughly 3/4 of the GHG emissions from human come from activities related to human energy use. Note also that most of the GHGs, when put on an even footing of CO2 equivalent is still carbon dioxide.<ref> Source: Climate Watch, based on raw data from IEA (2023), CO2 Emissions from Fuel Combustion, www.iea.org/statistics; modified by WRI.</ref>]]
 
The World Resource Institute has a nice article with an interactive Sankey diagram [https://www.wri.org/data/world-greenhouse-gas-emissions-2023 here].
 
==For Further Reading==
*[[High energy society]]
*[[Climate forcing]]
*[[Indicators of a warming world]]
*[[Climate change]]
*Or explore a [[Special:Random|random page]]


==References==
==References==
{{reflist}}
{{reflist}}
[[Category:Uploaded]]

Latest revision as of 20:55, 2 July 2026

Figure 1. Carbon is trapped underground in reservoirs, extracted, and used by humans through the process of combustion. This causes a release of carbon dioxide (and other carbon compounds) which would otherwise not reach the atmosphere, ocean, or soil.[1]

Anthropogenic carbon emissions are any emissions of carbon that are associated with human activities. The two most concerning forms are carbon dioxide and methane. Examples of human activities which emit carbon include the burning of fossil fuels, deforestation, changes in land use, livestock, fertilization, and anything else that results in a net increase in emissions.[2]

Increasing Carbon Levels

A major concern is the emission of carbon dioxide (CO2) - a type of greenhouse gas - which contributes to global warming and ocean acidification. CO2 and other compounds of carbon are exchanged throughout carbon pools in the global carbon cycle. The natural carbon cycle is kept in a near perfect balance. However, human emissions are constantly added into the cycle which causes a net increase in concentrations of carbon in the atmosphere, soil, and oceans, as seen in Figure 1.[3]

Methane (CH4), carbon monoxide, and black carbon are all present in the atmosphere, and each have varying effects on the planet. The amount of each of these in the atmosphere has been increasing rapidly: the amount of carbon dioxide in the atmosphere has increased by about 40% since the industrial era, and methane by about 150%.[3] These levels had been relatively stable for around 10 thousand years prior to this.[4]

See carbon cycle for more information on increasing levels of carbon in Earth's crucial systems.

Measuring Emissions

Scientists have had to work hard to show that climate change is caused by the greenhouse gasses that humans emit. Part of the reason that this was tricky is that nature does emit nearly 20 times more CO2 into the atmosphere than humans do, but it's the new carbon that humans introduce that changes the amount of carbon in the system.[3] This section highlights techniques and observational evidence to support the impact that humans have had on the environment.

There are many scientific methods that allow for the measurements of human emissions, two of which will be talked about here:

  1. The first method is the investigation of carbon-14 (14C), a radioactive isotope of carbon. 14C is found naturally in atmospheric CO2, however it is not present in fossil fuels that humans extract from underground. This is because fossil fuels were formed millions of years ago, far longer than the half life of 14C (t1/2 = 5730 years), meaning that all of the 14C has decayed away.[3] This means that carbon emitted by these fuels does not contain any 14C. By measuring levels of 14C and CO2 over time, it is found that the vast majority of excess CO2 does not contain 14C and therefore can be attributed to fossil fuels.
  2. The second method relates to changes in atmospheric oxygen levels. It is employed in order to determine whether this excess CO2 is indeed from human fossil fuels, or if it is instead from the likes of volcanic eruptions. This method works off of basic hydrocarbon combustion knowledge - when a fossil fuel is burned, its hydrocarbons consume oxygen in order to give off energy, along with water vapour and carbon dioxide. Therefore oxygen levels are expected to decrease when humans burn fossils fuels, and when measuring levels over time it is found that they do, the amounts of which are in accordance with measured carbon dioxide levels. If the emissions were instead dominantly from volcanoes, there would be no measured decrease in atmospheric oxygen levels.[3]

Where do these Emissions Go?

The net destination of emissions from human activities is seen in Figure 2 below. This figure shows the flow of anthropogenic carbon from its emission (dominantly from fossil fuel combustion), to the atmosphere. Once these greenhouse gasses have been emitted, natural processes move these around and they settle in different carbon pools: the atmosphere, the ocean and the land. Over the past few decades the amount that's ending up in the different carbon pools is shifting more heavily towards the atmosphere.

Figure 2. The net emissions from human activity go into the atmosphere, and natural processes distribute those GHGs into three broad carbon pools. With roughly half staying in the atmosphere and the other half being somewhat evenly split between the land and the ocean.[3] [5]

Where do these Emissions Come from?

The Sankey diagram below shows where the world's GHG emissions come from. As seen in figure 3, the majority of the emissions come from natural gas, oil and coal that are used for the world's primary energy. While methane and other greenhouse gasses are a problem, carbon dioxide is the biggest contributor to changing the world's climate.

Figure 3. Roughly 3/4 of the GHG emissions from human come from activities related to human energy use. Note also that most of the GHGs, when put on an even footing of CO2 equivalent is still carbon dioxide.[6]

The World Resource Institute has a nice article with an interactive Sankey diagram here.

For Further Reading

References

  1. ↑ Created internally by a member of the Energy Education team.
  2. ↑ IPCC, 2012: Glossary of terms. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, UK, and New York, NY, USA, pp. 555-564.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 M. Melieres and C. Marechal, "Warming in the 20th century," in Climate Change: Past, Present and Future 1st ed., U.K.: Wiley, 2015, ch.29, sec.3, pp. 310-312
  4. ↑ IPCC, The Natural Carbon Cycle [Online], Available: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch7s7-3.html
  5. ↑ Images taken from https://www.pxfuel.com/en/free-photo-jdbya https://commons.wikimedia.org/wiki/File:Stenshuvud_forrest.jpg
  6. ↑ Source: Climate Watch, based on raw data from IEA (2023), CO2 Emissions from Fuel Combustion, www.iea.org/statistics; modified by WRI.
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