Which Of The Following Primarily Contributes To Climate Change And Global Warming?

Homo and natural factors both influence the earth's climate, just the long-term tendency observed over the by century can just be explained by the consequence of homo activities on climate. Source: U.S. Global Modify Enquiry Program, Quaternary National Climate Assessment, Chapter two: Our Changing Climate, 2017.

Since the Industrial Revolution, human activities take released large amounts of carbon dioxide and other greenhouse gases into the temper, which has changed the earth'southward climate. Natural processes, such as changes in the lord's day'southward energy and volcanic eruptions, also touch the earth's climate. However, they practice not explain the warming that nosotros accept observed over the final century.¹

Human Versus Natural Causes

Scientists accept pieced together a record of the world's climate by analyzing a number of indirect measures of climate, such equally water ice cores, tree rings, glacier lengths, pollen remains, and ocean sediments, and by studying changes in the earth'due south orbit around the sun.² This record shows that the climate varies naturally over a wide range of fourth dimension scales, but this variability does not explain the observed warming since the 1950s. Rather, it is extremely likely (> 95%) that human activities have been the dominant cause of that warming.³

Human activities take contributed substantially to climatic change through:

Greenhouse Gas Emissions
Reflectivity or Absorption of the Sun's Free energy

Heat-trapping Greenhouse Gases And The Earth's Climate

Source: Smithsonian National Museum of Natural History, 2018

Greenhouse Gases

Concentrations of the primal greenhouse gases have all increased since the Industrial Revolution due to human activities. Carbon dioxide, methane, and nitrous oxide concentrations are at present more abundant in the earth's atmosphere than any time in the last 800,000 years.⁵ These greenhouse gas emissions have increased the greenhouse outcome and caused the earth's surface temperature to ascension. Called-for fossil fuels changes the climate more than any other human activity.

Carbon dioxide: Man activities currently release over 30 billion tons of carbon dioxide into the atmosphere every year.⁶ Atmospheric carbon dioxide concentrations have increased past more than forty percent since pre-industrial times, from approximately 280 parts per one thousand thousand (ppm) in the 18th century⁷ to 414 ppm in 2020.⁸

Methane: Human activities increased methane concentrations during most of the 20th century to more than 2.5 times the pre-industrial level, from approximately 722 parts per billion (ppb) in the 18th century^ix to ane,867 ppb in 2019.^ten

Nitrous oxide: Nitrous oxide concentrations have risen approximately 20 pct since the start of the Industrial Revolution, with a relatively rapid increase toward the end of the 20th century. Nitrous oxide concentrations have increased from a pre-industrial level of 270 ppb^eleven to 332 ppb in 2019.¹²

For more information on greenhouse gas emissions, see the Greenhouse Gas Emissions website. To learn more virtually actions that can reduce these emissions, come across What You Can Practise.

Graph showing concentrations of key greenhouse gases. — This graph shows the increment in atmospheric concentrations of three of the key greenhouse gases over the terminal 2,000 years. Increases in concentrations of these gases since 1750 are due to human activities in the industrial era. Source: U.Due south. EPA, Climate Change Indicators in the United States: Atmospheric Concentrations of Greenhouse Gases, 2021.

Reflectivity or Absorption of the Sun's Energy

Activities such as agronomics, road structure, and deforestation tin can change the reflectivity of the earth's surface, leading to local warming or cooling. This effect is observed in heat islands, which are urban centers that are warmer than the surrounding, less populated areas. I reason that these areas are warmer is that buildings, pavement, and roofs tend to reflect less sunlight than natural surfaces. While deforestation can increase the earth's reflectivity globally by replacing night trees with lighter surfaces such every bit crops, the net outcome of all land-use changes appears to be a minor cooling.¹³

Emissions of pocket-sized particles, known equally aerosols, into the air can also lead to reflection or absorption of the sun's energy. Many types of air pollutants undergo chemical reactions in the atmosphere to create aerosols. Overall, homo-generated aerosols take a net cooling effect on the globe. Learn more than about human-generated and natural aerosols.

Natural Processes

Natural processes are ever influencing the earth'southward climate and can explain climate changes prior to the Industrial Revolution in the 1700s. Nevertheless, recent climate changes cannot be explained by natural causes alone.

Changes in the World's Orbit and Rotation

Changes in the earth's orbit and its centrality of rotation have had a big impact on climate in the past. For example, the corporeality of summer sunshine on the Northern Hemisphere, which is afflicted past changes in the planet's orbit, appears to be the primary crusade of past cycles of water ice ages, in which the earth has experienced long periods of cold temperatures (ice ages), every bit well as shorter interglacial periods (periods between ice ages) of relatively warmer temperatures.¹⁴ At the coldest part of the concluding glacial period (or ice age), the average global temperature was about 11°F colder than information technology is today. At the peak of the last interglacial period, yet, the boilerplate global temperature was at most ii°F warmer than it is today.¹⁵

Variations in Solar Action

Changes in the sun's energy output can affect the intensity of the sunlight that reaches the earth's surface. While these changes can influence the earth's climate, solar variations have played trivial part in the climate changes observed in recent decades.¹⁶ Satellites accept been measuring the amount of free energy the earth receives from the sun since 1978. These measurements show no net increase in the sunday's output, even equally global surface temperatures accept risen.¹⁷

Measurements of Global Average Surface Temperature and the Sun's Energy — The lord's day follows a natural 11-twelvemonth cycle of modest ups and downs in intensity (lesser chart), but the effect on the earth is pocket-sized. Over the same menstruum, the boilerplate global temperature has increased markedly (top chart). Source: National Academy of Sciences, Climatic change Evidence & Causes, 2020.

Changes in the Earth'due south Reflectivity

The amount of sunlight that is captivated or reflected by the planet depends on the earth's surface and atmosphere. Night objects and surfaces, similar the body of water, forests, and soil, tend to absorb more sunlight. Low-cal-colored objects and surfaces, similar snowfall and clouds, tend to reverberate sunlight. About seventy percent of the sunlight that reaches the earth is absorbed.¹⁸ Natural changes in the earth's surface, like the melting of sea ice, have contributed to climate change in the past, often acting as feedbacks to other processes.

Volcanic Action

Volcanoes have played a noticeable role in climate, and volcanic eruptions released big quantities of carbon dioxide in the distant past. Some explosive volcano eruptions can throw particles (e.g., And then₂) into the upper atmosphere, where they can reflect enough sunlight dorsum to space to absurd the surface of the planet for several years.^nineteen These particles are an example of cooling aerosols.

Volcanic particles from a single eruption do not produce long-term climate modify considering they remain in the atmosphere for a much shorter time than greenhouse gases. In add-on, human being activities emit more 100 times as much carbon dioxide as volcanoes each twelvemonth.^xx

Changes in Naturally Occurring Carbon Dioxide Concentrations

Over the concluding several hundred one thousand years, carbon dioxide levels varied in tandem with the glacial cycles. During warm interglacial periods, carbon dioxide levels were higher. During cool glacial periods, carbon dioxide levels were lower.²¹ The heating or cooling of the earth'southward surface and oceans tin cause changes in the natural sources and sinks of these gases, and thus change greenhouse gas concentrations in the atmosphere.²² These irresolute concentrations have acted every bit a positive climate feedback, amplifying the temperature changes caused past long-term shifts in the globe's orbit.²³

A graph of atmospheric carbon dioxide concentrations. — Analyses of ice cadre data extending back 800,000 years testify that warmer periods on the earth coincide with periods of relatively loftier atmospheric carbon dioxide concentrations. Source: Based on information actualization in NAS, Climate change Evidence & Causes, 2020.

¹ National Academy of Sciences. (2020). Climatic change: Evidence and causes: Update 2020. The National Academies Press, Washington, DC, p. 5. doi: 10.17226/25733

²Wuebbles, D.J., D.Westward. Fahey, K.A. Hibbard, B. DeAngelo, Due south. Doherty, K. Hayhoe, R. Horton, J.P. Kossin, P.C. Taylor, A.Thou. Waple & C.P. Weaver. (2017). Executive summary. In: Climate science special report: Fourth national climate assessment, volume I [Wuebbles, D.J., D.W. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart & T.One thousand. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, pp. 12–34, doi: x.7930/J0DJ5CTG

National Academy of Sciences. (2020). Climate change: Prove and causes: Update 2020. The National Academies Printing, Washington, DC, p. 5. doi: x.17226/25733

^threeIPCC (2013). Climatic change 2013: The physical scientific discipline basis.Working Group I contribution to the fifth assessment report of the Intergovernmental Panel on Climatic change [Stocker, T.F., D. Qin, Thousand.-K. Plattner, Yard. Tignor, Due south.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex & P.M. Midgley (eds.)]. Cambridge Academy Press, Cambridge, Uk and New York, NY, p. 869.

⁴IPCC. (2021). Climatic change 2021: The concrete scientific discipline ground. Working Group I contribution to the 6th assessment report of the Intergovernmental Console on Climatic change [Masson-Delmotte, 5., P. Zhai, A. Pirani, Due south.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, Yard.I. Gomis, Thousand. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.G. Maycock, T. Waterfield, O. Yelekçi, R. Yu & B. Zhou (eds.)]. Cambridge University Printing, Cambridge, United Kingdom, p. SPM-5.

^vNational Academy of Sciences. (2020). Climatic change: Show and causes: Update 2020. The National Academies Press, Washington, DC, p. B-two. doi: x.17226/25733

Fahey, D.Westward., S.J. Doherty, K.A. Hibbard, A. Romanou & P.C. Taylor. (2017).Concrete drivers of climate change. In: Climate science special report: Fourth national climate cess, volume I [Wuebbles, D.J., D.Due west. Fahey, K.A. Hibbard, D.J. Dokken, B.C. Stewart & T.K. Maycock (eds.)]. U.S. Global Modify Research Program, Washington, DC, p. 80, Effigy two.4. doi: 10.7930/J0513WCR

⁶Hayhoe, K., D.J. Wuebbles, D.R. Easterling, D.W. Fahey, S. Doherty, J. Kossin, W. Sugariness, R. Vose & M. Wehner. (2018). Our changing climate. In: Impacts, risks, and adaptation in the United States: Fourth national climate assessment, volume Two [Reidmiller, D.R., C.W. Avery, D.R. Easterling, M.Eastward. Kunkel, One thousand.L.M. Lewis, T.K. Maycock & B.C. Stewart (eds.)]. U.S. Global Change Inquiry Program, Washington, DC, p. 76. doi: ten.7930/NCA4.2018

^sevenIPCC. (2013). Climatic change 2013: The concrete science basis.Working Group I contribution to the fifth cess study of the Intergovernmental Console on Climate Change [Stocker, T.F., D. Qin, One thousand.-Thousand. Plattner, M. Tignor, S.One thousand. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex & P.K. Midgley (eds.)]. Cambridge University Press, Cambridge, United kingdom, and New York, NY, p. 166.

⁸ NOAA. (2021). Trends in atmospheric carbon dioxide. Retrieved 3/25/2021. esrl.noaa.gov/gmd/ccgg/trends/mlo.html

^nine IPCC. (2013).Climate modify 2013: The physical scientific discipline basis.Working Group I contribution to the fifth assessment study of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, Chiliad.-K. Plattner, Thousand. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, Five. Bex & P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom, and New York, NY, p. 167.

^x NOAA. (2021). Trends in atmospheric methane. Retrieved 3/25/2021. esrl.noaa.gov/gmd/ccgg/trends_ch4

¹¹ IPCC. (2013).Climate modify 2013: The physical scientific discipline basis.Working Grouping I contribution to the 5th cess report of the Intergovernmental Panel on Climate change [Stocker, T.F., D. Qin, One thousand.-K. Plattner, 1000. Tignor, S.M. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex & P.M. Midgley (eds.)]. Cambridge Academy Press, Cambridge, United Kingdom, and New York, NY, p. 168.

¹² NOAA. (2021). Trends in nitrous oxide. Retrieved 3/25/2021. esrl.noaa.gov/gmd/ccgg/trends_n2o/

¹³ Fahey, D.West., S.J. Doherty, G.A. Hibbard, A. Romanou & P.C. Taylor. (2017). Physical drivers of climatic change. In: Climate science special report: Fourth national climate assessment, volume I [Wuebbles, D.J., D.Westward. Fahey, M.A. Hibbard, D.J. Dokken, B.C. Stewart & T.Chiliad. Maycock (eds.)]. U.Due south. Global Change Research Program, Washington, DC, p. 78, Fig. two.three and p. 86. doi: 10.7930/J0513WCR

¹⁴ National Academy of Sciences. (2020). Climate alter: Evidence and causes: Update 2020. The National Academies Press, Washington, DC, p. 9. doi: 10.17226/25733

^xv Fahey, D.West., S.J. Doherty, K.A. Hibbard, A. Romanou & P.C. Taylor. (2017). Our globally changing climate. In: Climate science special report: Fourth national climate assessment, volume I [Wuebbles, D.J., D.W. Fahey, G.A. Hibbard, D.J. Dokken, B.C. Stewart & T.Thou. Maycock (eds.)]. U.S. Global Change Research Program, Washington, DC, p. 53. doi: x.7930/J08S4N35

¹⁶ National Academy of Sciences. (2020). Climate alter: Show and causes: Update 2020. The National Academies Press, Washington, DC, p. 7. doi: 10.17226/25733

¹⁷ National Academy of Sciences. (2020). Climate change: Evidence and causes: Update 2020. The National Academies Press, Washington, DC, p. vii. doi: ten.17226/25733

¹⁸ Fahey, D.West., S.J. Doherty, Thousand.A. Hibbard, A. Romanou, & P.C. Taylor. (2017). Physical drivers of climate change. In: Climate science special study: Quaternary national climate assessment, book I [Wuebbles, D.J., D.W. Fahey, One thousand.A. Hibbard, D.J. Dokken, B.C. Stewart & T.K. Maycock (eds.)]. U.S. Global Change Inquiry Program, Washington, DC, p. ii. doi: 10.7930/J0513WCR

^nineteen Fahey, D.Due west., S.J. Doherty, K.A. Hibbard, A. Romanou, & P.C. Taylor. (2017). Physical drivers of climate change. In: Climate science special report: Fourth national climate cess, book I [Wuebbles, D.J., D.W. Fahey, One thousand.A. Hibbard, D.J. Dokken, B.C. Stewart & T.Thousand. Maycock (eds.)]. U.S. Global Change Enquiry Plan, Washington, DC, p. 79. doi: 10.7930/J0513WCR

²⁰ Fahey, D.West., Southward.J. Doherty, K.A. Hibbard, A. Romanou & P.C. Taylor. (2017). Physical drivers of climatic change. In: Climate science special report: Fourth national climate cess, volume I [Wuebbles, D.J., D.W. Fahey, 1000.A. Hibbard, D.J. Dokken, B.C. Stewart & T.Chiliad. Maycock (eds.)]. U.Due south. Global Change Research Program, Washington, DC, p. 79. doi: 10.7930/J0513WCR

²¹ National University of Sciences. (2020). Climate alter: Evidence and causes: Update 2020. The National Academies Press, Washington, DC, pp. 9–10. doi: x.17226/25733

²² IPCC. (2013).Climate change 2013: The physical scientific discipline ground.Working Group I contribution to the 5th assessment report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, K.-K. Plattner, Grand. Tignor, South.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex & P.Thou. Midgley (eds.)]. Cambridge University Press, Cambridge, Uk and New York, NY, p. 399.

²³ National Academy of Sciences. (2020). Climate change: Evidence and causes: Update 2020. The National Academies Press, Washington, DC, pp. ix–10. doi: 10.17226/25733