Editing Albedo (section)

==Examples of terrestrial albedo effects==
[[File:Albedo-e hg.svg|thumb|upright=1.3|The percentage of [[diffuse reflection|diffusely reflected]] [[sunlight]] relative to various surface conditions]]

=== Illumination ===
Albedo is not directly dependent on the illumination because changing the amount of incoming light proportionally changes the amount of reflected light, except in circumstances where a change in illumination induces a change in the Earth's surface at that location (e.g. through melting of reflective ice). However, albedo and illumination both vary by latitude. Albedo is highest near the poles and lowest in the subtropics, with a local maximum in the tropics.<ref name="Winston">{{cite journal| first=Jay |last=Winston |title=The Annual Course of Zonal Mean Albedo as Derived From ESSA 3 and 5 Digitized Picture Data |journal=Monthly Weather Review |volume=99 |pages=818–827| bibcode=1971MWRv...99..818W| date=1971| doi=10.1175/1520-0493(1971)099<0818:TACOZM>2.3.CO;2| issue=11|doi-access=free}}</ref>

===Insolation effects===
The intensity of albedo temperature effects depends on the amount of albedo and the level of local [[insolation]] ([[solar irradiance]]); high albedo areas in the [[Arctic]] and [[Antarctic]] regions are cold due to low insolation, whereas areas such as the [[Sahara Desert]], which also have a relatively high albedo, will be hotter due to high insolation. [[Tropical]] and [[sub-tropical]] [[rainforest]] areas have low albedo, and are much hotter than their [[temperate forest]] counterparts, which have lower insolation. Because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes.<ref>{{cite web |title=Albedo Effect |url=https://www.npolar.no/en/fact/albedo/ |website=Norsk PolarInstitutt |publisher=Norwegian Polar Institute |access-date=23 June 2023}}</ref>

Arctic regions notably release more heat back into space than what they absorb, effectively cooling the [[Earth]]. This has been a concern since arctic ice and [[snow]] has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being water or ground which is darker color) and reflects less heat back into space. This [[Ice–albedo feedback|feedback loop]] results in a reduced albedo effect.<ref>{{Cite news|url=https://www.economist.com/news/briefing/21721364-commercial-opportunities-are-vastly-outweighed-damage-climate-thawing-arctic|title=The thawing Arctic threatens an environmental catastrophe|newspaper=The Economist|access-date=8 May 2017|date=29 April 2017}}</ref>

===Climate and weather===
{{See also|Climate change feedback}}
[[File:20220726 Feedbacks affecting global warming and climate change - block diagram.svg|thumb|right|upright=1.5| Some effects of global warming can either enhance ([[positive feedback]]s such as the ice-albedo feedback) or inhibit ([[negative feedback]]s) warming.<ref name=NASA_IntegratedSystem>{{cite web |title=The Study of Earth as an Integrated System |url=https://climate.nasa.gov/nasa_science/science/ |website=nasa.gov |publisher=NASA |date=2016 |archive-url=https://web.archive.org/web/20161102022200/https://climate.nasa.gov/nasa_science/science/ |archive-date=2 November 2016 |url-status=live }}</ref><ref name=IPCC_AR6_SGI_FigTS.17>Fig. TS.17, ''[https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf Technical Summary],'' Sixth Assessment Report (AR6), Working Group I, IPCC, 2021, p. 96. [https://web.archive.org/web/20220721021347/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf Archived] from the original on 21 July 2022.</ref>]]
Albedo affects [[climate]] by determining how much [[radiation]] a planet absorbs.<ref>{{Cite book|url=https://books.google.com/books?id=av7q4N8Ib6sC&pg=PA53|title=Encyclopedia of Climate and Weather: Abs-Ero|last1=Schneider|first1=Stephen Henry|last2=Mastrandrea|first2=Michael D.|last3=Root|first3=Terry L.|date=2011|publisher=Oxford University Press|isbn=978-0-19-976532-4|page=53}}</ref> The uneven heating of Earth from albedo variations between land, ice, or ocean surfaces can drive [[weather]].<ref>{{Cite web |title=Albedo and Climate {{!}} Center for Science Education |url=https://scied.ucar.edu/learning-zone/how-climate-works/albedo-and-climate |access-date=2025-02-06 |website=scied.ucar.edu}}</ref>

The response of the climate system to an initial forcing is modified by feedbacks: increased by [[Positive feedback|"self-reinforcing" or "positive" feedbacks]] and reduced by [[Negative feedback|"balancing" or "negative" feedbacks]].<ref>{{cite web |year=2013 |title=The study of Earth as an integrated system |url=https://climate.nasa.gov/nasa_science/science/ |url-status=live |archive-url=https://web.archive.org/web/20190226190002/https://climate.nasa.gov/nasa_science/science/ |archive-date=26 February 2019 |series=Vitals Signs of the Planet |publisher=Earth Science Communications Team at NASA's Jet Propulsion Laboratory / California Institute of Technology}}</ref> The main reinforcing feedbacks are the [[Water vapour feedback|water-vapour feedback]], the [[ice–albedo feedback]], and the net effect of clouds.<ref>Arias, P.A., N. Bellouin, E. Coppola, R.G. Jones, G. Krinner, J. Marotzke, V. Naik, M.D. Palmer, G.-K. Plattner, J. Rogelj, M. Rojas, J. Sillmann, T. Storelvmo, P.W. Thorne, B. Trewin, K. Achuta Rao, B. Adhikary, R.P. Allan, K. Armour, G. Bala, R. Barimalala, S. Berger, J.G. Canadell, C. Cassou, A. Cherchi, W. Collins, W.D. Collins, S.L. Connors, S. Corti, F. Cruz, F.J. Dentener, C. Dereczynski, A. Di Luca, A. Diongue Niang, F.J. Doblas-Reyes, A. Dosio, H. Douville, F. Engelbrecht, V. Eyring, E. Fischer, P. Forster, B. Fox-Kemper, J.S. Fuglestvedt, J.C. Fyfe, et al., 2021: [https://www.ipcc.ch/report/ar6/wg1/chapter/technical-summary/ Technical Summary]. In ''[https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change]'' [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 33−144. doi: 10.1017/9781009157896.002.</ref>{{rp|58}}

===Albedo–temperature feedback===
{{Further|Ice–albedo feedback}}
When an area's albedo changes due to snowfall, a snow–temperature [[feedback]] results. A layer of snowfall increases local albedo, reflecting away sunlight, leading to local cooling. In principle, if no outside temperature change affects this area (e.g., a warm [[air mass]]), the raised albedo and lower temperature would maintain the current snow and invite further snowfall, deepening the snow–temperature feedback. However, because local [[weather]] is dynamic due to the change of [[season]]s, eventually warm air masses and a more direct angle of sunlight (higher [[insolation]]) cause melting. When the melted area reveals surfaces with lower albedo, such as grass, soil, or ocean, the effect is reversed: the darkening surface lowers albedo, increasing local temperatures, which induces more melting and thus reducing the albedo further, resulting in still more heating.

===Snow===
Snow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow.<ref>{{cite book |last1=Hall |first1=Dorothy K. |author-link=Dorothy Hall (scientist)|title=Remote Sensing of Ice and Snow |date=1985 |publisher=Springer Netherlands |location=Dordrecht |isbn=978-94-009-4842-6}}</ref> Over [[Antarctica]], snow albedo averages a little more than 0.8. If a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack (referred to as the [[Ice–albedo feedback|ice–albedo]] [[positive feedback]]).

In [[Switzerland]], the citizens have been protecting their glaciers with large white tarpaulins to slow down the ice melt. These large white sheets are helping to reject the rays from the sun and defecting the heat. Although this method is very expensive, it has been shown to work, reducing snow and ice melt by 60%.<ref>{{Cite web |last=swissinfo.ch/gw |date=2021-04-02 |title=Glacier tarpaulins an effective but expensive shield against heat |url=https://www.swissinfo.ch/eng/sci-&-tech/glacier-tarpaulins-an-effective-but-expensive-shield-against-heat/46501004 |access-date=2024-02-20 |website=SWI swissinfo.ch |language=en-GB}}</ref>

Just as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. Sea water absorbs more [[solar radiation]] than would the same surface covered with reflective snow. When sea ice melts, either due to a rise in sea temperature or in response to increased solar radiation from above, the snow-covered surface is reduced, and more surface of sea water is exposed, so the rate of energy absorption increases. The extra absorbed energy heats the sea water, which in turn increases the rate at which sea ice melts. As with the preceding example of snowmelt, the process of melting of sea ice is thus another example of a positive feedback.<ref>"All About Sea Ice." National Snow and Ice Data Center. Accessed 16 November 2017. /cryosphere/seaice/index.html.</ref> Both positive feedback loops have long been recognized as important for [[global warming]].{{citation needed|date=January 2018}}

[[Cryoconite]], powdery windblown [[dust]] containing soot, sometimes reduces albedo on glaciers and ice sheets.<ref name="Nat. Geo">[http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 "Changing Greenland – Melt Zone"] {{Webarchive|url=https://web.archive.org/web/20160303175416/http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 |url2=https://archive.wikiwix.com/cache/20110806084123/http://ngm.nationalgeographic.com/2010/06/melt-zone/jenkins-text/3 |date=3 March 2016 |date2= 6 August 2011}} page 3, of 4, article by Mark Jenkins in ''[[National Geographic (magazine)|National Geographic]]'' June 2010, accessed 8 July 2010</ref>

The dynamical nature of albedo in response to positive feedback, together with the effects of small errors in the measurement of albedo, can lead to large errors in energy estimates. Because of this, in order to reduce the error of energy estimates, it is important to measure the albedo of snow-covered areas through [[remote sensing]] techniques rather than applying a single value for albedo over broad regions.{{citation needed|date=January 2018}}

===Small-scale effects===
Albedo works on a smaller scale, too. In sunlight, dark clothes absorb more heat and light-coloured clothes reflect it better, thus allowing some control over body temperature by exploiting the albedo effect of the colour of external clothing.<ref name="ranknfile-ue">{{cite web|url=http://www.ranknfile-ue.org/h&s0897.html |title=Health and Safety: Be Cool! (August 1997) |publisher=Ranknfile-ue.org |access-date=19 August 2011}}</ref>

=== Solar photovoltaic effects ===
Albedo can affect the [[electrical energy]] output of solar [[photovoltaic system|photovoltaic devices]]. For example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si)-based compared to traditional spectral-integrated albedo predictions. Research showed impacts of over 10% for vertically (90°) mounted systems, but such effects were substantially lower for systems with lower surface tilts.<ref>{{cite journal | last1 = Andrews | first1 = Rob W. | last2 = Pearce | first2 = Joshua M. | date = 2013 | title = The effect of spectral albedo on amorphous silicon and crystalline silicon solar photovoltaic device performance | journal = Solar Energy | volume = 91 | pages = 233–241 | doi = 10.1016/j.solener.2013.01.030 |bibcode = 2013SoEn...91..233A | url = https://www.academia.edu/3081684 }}</ref> Spectral albedo strongly affects the performance of [[bifacial solar cells]] where rear surface performance gains of over 20% have been observed for c-Si cells installed above healthy vegetation.<ref>{{cite journal | last1 = Riedel-Lyngskær | first1 = Nicholas| last2 = Ribaconka | first2 = Ribaconka | last3 = Po | first3 = Mario | last4 = Thorseth | first4 = Anders | last5 = Thorsteinsson | first5 = Sune | last6 = Dam-Hansen | first6 = Carsten | last7 = Jakobsen | first7 = Michael L. | date = 2022| title = The effect of spectral albedo in bifacial photovoltaic performance | journal = Solar Energy | volume = 231| pages = 921–935 | doi = 10.1016/j.solener.2021.12.023 | bibcode = 2022SoEn..231..921R| s2cid = 245488941| doi-access = free }}</ref> An analysis on the bias due to the specular reflectivity of 22 commonly occurring surface materials (both human-made and natural) provided effective albedo values for simulating the performance of seven photovoltaic materials mounted on three common photovoltaic system topologies: industrial (solar farms), commercial flat rooftops and residential pitched-roof applications.<ref>{{cite journal | last1 = Brennan | first1 = M.P. | author-link4 = J. M. Pearce | last2 = Abramase | first2 = A.L. | last3 = Andrews | first3 = R.W. | last4 = Pearce | first4 = J. M. | date = 2014 | title = Effects of spectral albedo on solar photovoltaic devices | journal = Solar Energy Materials and Solar Cells | volume = 124 | pages = 111–116 | doi = 10.1016/j.solmat.2014.01.046 | bibcode = 2014SEMSC.124..111B | url = https://www.academia.edu/6222506 }}</ref>

===Trees===
{{Update section|date=March 2023|reason=the references used are quite old; there must be more updated information available in the [[IPCC Sixth Assessment Report]]}}
{{See also|Climate change#Land surface changes}}
Forests generally have a low albedo because the majority of the ultraviolet and [[visible spectrum]] is absorbed through [[photosynthesis]]. For this reason, the greater heat absorption by trees could offset some of the carbon benefits of [[afforestation]] (or offset the negative climate impacts of [[deforestation]]). In other words: The [[climate change mitigation]] effect of [[carbon sequestration]] by forests is partially counterbalanced in that [[reforestation]] can decrease the reflection of sunlight (albedo).<ref>{{cite journal |last1=Zhao |first1=Kaiguang |last2=Jackson |first2=Robert B |title=Biophysical forcings of land-use changes from potential forestry activities in North America |journal=Ecological Monographs |date=2014 |volume=84 |issue=2 |pages=329–353 |doi=10.1890/12-1705.1 |bibcode=2014EcoM...84..329Z |s2cid=56059160 |url=https://jacksonlab.stanford.edu/sites/g/files/sbiybj20871/files/media/file/em2014.pdf}}</ref>

In the case of evergreen forests with seasonal snow cover, albedo reduction may be significant enough for deforestation to cause a net cooling effect.<ref name="Betts" /> Trees also impact climate in extremely complicated ways through [[evapotranspiration]]. The water vapor causes cooling on the land surface, causes heating where it condenses, acts as strong greenhouse gas, and can increase albedo when it condenses into clouds.<ref>{{cite journal | last1 = Boucher | date = 2004 | title = Direct human influence of irrigation on atmospheric water vapour and climate | journal = Climate Dynamics | volume = 22 | issue = 6–7| pages = 597–603 | doi=10.1007/s00382-004-0402-4|display-authors=etal|bibcode = 2004ClDy...22..597B | s2cid = 129640195 | url = https://www.academia.edu/25329256}}</ref> Scientists generally treat evapotranspiration as a net cooling impact, and the net climate impact of albedo and evapotranspiration changes from deforestation depends greatly on local climate.<ref>{{cite journal | last1 = Bonan | first1 = GB | date = 2008 | title = Forests and Climate Change: Forcings, Feedbacks, and the Climate Benefits of Forests | journal = Science | volume = 320 | issue = 5882| pages = 1444–1449 | doi = 10.1126/science.1155121 | pmid=18556546|bibcode = 2008Sci...320.1444B  | s2cid = 45466312 | url = https://zenodo.org/record/1230896 }}</ref>

Mid-to-high-latitude forests have a much lower albedo during snow seasons than flat ground, thus contributing to warming. Modeling that compares the effects of albedo differences between forests and grasslands suggests that expanding the land area of forests in temperate zones offers only a temporary mitigation benefit.<ref>{{cite web |author=Jonathan Amos |date=15 December 2006 |title=Care needed with carbon offsets |url=http://news.bbc.co.uk/1/hi/sci/tech/6184577.stm |access-date=8 July 2008 |publisher=BBC}}</ref><ref>{{cite web |date=5 December 2005 |title=Models show growing more forests in temperate regions could contribute to global warming |url=https://publicaffairs.llnl.gov/news/news_releases/2005/NR-05-12-04.html |url-status=dead |archive-url=https://web.archive.org/web/20100527212654/https://publicaffairs.llnl.gov/news/news_releases/2005/NR-05-12-04.html |archive-date=27 May 2010 |access-date=8 July 2008 |publisher=Lawrence Livermore National Laboratory}}</ref><ref>{{cite journal |author1=S. Gibbard |author2=K. Caldeira |author3=G. Bala |author4=T. J. Phillips |author5=M. Wickett |date=December 2005 |title=Climate effects of global land cover change |url=https://digital.library.unt.edu/ark:/67531/metadc874513/ |journal=Geophysical Research Letters |volume=32 |issue=23 |pages=L23705 |bibcode=2005GeoRL..3223705G |doi=10.1029/2005GL024550 |doi-access=free}}</ref><ref>{{cite journal |last1=Malhi |first1=Yadvinder |last2=Meir |first2=Patrick |last3=Brown |first3=Sandra |year=2002 |title=Forests, carbon and global climate |journal=Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences |volume=360 |issue=1797 |pages=1567–91 |bibcode=2002RSPTA.360.1567M |doi=10.1098/rsta.2002.1020 |pmid=12460485 |s2cid=1864078}}</ref>

In seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. [[Deciduous trees]] have an albedo value of about 0.15 to 0.18 whereas [[coniferous trees]] have a value of about 0.09 to 0.15.<ref name="mmutrees" /> Variation in summer albedo across both forest types is associated with maximum rates of photosynthesis because plants with high growth capacity display a greater fraction of their foliage for direct interception of incoming radiation in the upper canopy.<ref name="Ollinger">{{cite journal
| title = Canopy nitrogen, carbon assimilation and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks
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}}</ref> The result is that wavelengths of light not used in photosynthesis are more likely to be reflected back to space rather than being absorbed by other surfaces lower in the canopy.

Studies by the [[Hadley Centre]] have investigated the relative (generally warming) effect of albedo change and (cooling) effect of [[carbon sequestration]] on planting forests. They found that new forests in tropical and midlatitude areas tended to cool; new forests in high latitudes (e.g., Siberia) were neutral or perhaps warming.<ref name="Betts" />

Research in 2023, drawing from 176 flux stations globally, revealed a climate trade-off: increased carbon uptake from [[afforestation]] results in reduced albedo. Initially, this reduction may lead to moderate global warming over a span of approximately 20 years, but it is expected to transition into significant cooling thereafter.<ref>{{Cite journal |last1=Graf |first1=Alexander |last2=Wohlfahrt |first2=Georg |last3=Aranda-Barranco |first3=Sergio |last4=Arriga |first4=Nicola |last5=Brümmer |first5=Christian |last6=Ceschia |first6=Eric |last7=Ciais |first7=Philippe |last8=Desai |first8=Ankur R. |last9=Di Lonardo |first9=Sara |last10=Gharun |first10=Mana |last11=Grünwald |first11=Thomas |last12=Hörtnagl |first12=Lukas |last13=Kasak |first13=Kuno |last14=Klosterhalfen |first14=Anne |last15=Knohl |first15=Alexander |date=2023-08-25 |title=Joint optimization of land carbon uptake and albedo can help achieve moderate instantaneous and long-term cooling effects |journal=Communications Earth & Environment |language=en |volume=4 |issue=1 |page=298 |doi=10.1038/s43247-023-00958-4 |pmid=38665193 |pmc=11041785 |bibcode=2023ComEE...4..298G |issn=2662-4435 |hdl-access=free |hdl=10481/85323}}</ref>

===Water===
[[File:water reflectivity.jpg|thumb|upright=1.3|Reflectivity of smooth water at {{convert|20|C|F}} (refractive index=1.333)]]
Water reflects light very differently from typical terrestrial materials. The reflectivity of a water surface is calculated using the [[Fresnel equations]].

At the scale of the wavelength of light even wavy water is always smooth so the light is reflected in a locally [[specular reflection|specular manner]] (not [[Diffuse reflection|diffusely]]). The glint of light off water is a commonplace effect of this. At small [[angle of incidence (optics)|angles of incident]] light, [[waviness]] results in reduced reflectivity because of the steepness of the reflectivity-vs.-incident-angle curve and a locally increased average incident angle.<ref name="Fresnel" />

Although the reflectivity of water is very low at low and medium angles of incident light, it becomes very high at high angles of incident light such as those that occur on the illuminated side of Earth near the [[terminator (solar)|terminator]] (early morning, late afternoon, and near the poles). However, as mentioned above, waviness causes an appreciable reduction. Because light specularly reflected from water does not usually reach the viewer, water is usually considered to have a very low albedo in spite of its high reflectivity at high angles of incident light.

Note that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. Fresh 'black' ice exhibits Fresnel reflection.
Snow on top of this sea ice increases the albedo to 0.9.<ref>{{Cite web |date=2007-01-31 |title=Arctic Reflection: Clouds Replace Snow and Ice as Solar Reflector |url=https://earthobservatory.nasa.gov/features/ArcticReflector/arctic_reflector4.php |access-date=2022-04-28 |website=earthobservatory.nasa.gov |language=en}}</ref>

===Clouds===
[[Cloud albedo]] has substantial influence over atmospheric temperatures. Different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. "On any given day, about half of Earth is covered by clouds, which reflect more sunlight than land and water. Clouds keep Earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth."<ref name="livescience">{{cite web|url=http://www.livescience.com/environment/060124_earth_albedo.html |title=Baffled Scientists Say Less Sunlight Reaching Earth |publisher=LiveScience |date=24 January 2006 |access-date=19 August 2011}}</ref>

Albedo and climate in some areas are affected by artificial clouds, such as those created by the [[contrail]]s of heavy commercial airliner traffic.<ref>{{cite journal|title=Contrails reduce daily temperature range|url=http://facstaff.uww.edu/travisd/pdf/jetcontrailsrecentresearch.pdf|journal=Nature |access-date=7 July 2015|archive-url=https://web.archive.org/web/20060503192714/http://facstaff.uww.edu/travisd/pdf/jetcontrailsrecentresearch.pdf|archive-date=3 May 2006|page=601|volume=418|issue=6898|date=8 August 2002|url-status=dead|doi=10.1038/418601a|bibcode = 2002Natur.418..601T|pmid=12167846|last1=Travis|first1=D. J.|last2=Carleton|first2=A. M.|last3=Lauritsen|first3=R. G.|s2cid=4425866}}</ref> A study following the burning of the Kuwaiti oil fields during Iraqi occupation showed that temperatures under the burning oil fires were as much as {{convert|10|C-change|0}} colder than temperatures several miles away under clear skies.<ref name="harvard">{{cite journal |title=The Kuwait oil fires as seen by Landsat |date=30 May 1991|bibcode=1992JGR....9714565C |last1=Cahalan |first1=Robert F. |volume=97 |issue=D13 |page=14565 |journal=Journal of Geophysical Research: Atmospheres |doi=10.1029/92JD00799|url=https://www.researchgate.net/publication/23842551 }}</ref>

===Aerosol effects===
[[Aerosols]] (very fine particles/droplets in the atmosphere) have both direct and indirect effects on Earth's radiative balance. The direct (albedo) effect is generally to cool the planet; the indirect effect (the particles act as [[cloud condensation nuclei]] and thereby change cloud properties) is less certain.<ref name="girda">{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/231.htm#671 |title=Climate Change 2001: The Scientific Basis |publisher=Grida.no |access-date=19 August 2011| archive-url= https://web.archive.org/web/20110629175429/http://www.grida.no/climate/ipcc_tar/wg1/231.htm| archive-date= 29 June 2011<!--Added by DASHBot-->}}</ref>

===Black carbon===
Another albedo-related effect on the climate is from [[black carbon]] particles. The size of this effect is difficult to quantify: the [[Intergovernmental Panel on Climate Change]] estimates that the global mean [[radiative forcing]] for black carbon aerosols from fossil fuels is +0.2 W m<sup>−2</sup>, with a range +0.1 to +0.4 W m<sup>−2</sup>.<ref name="girda 1">{{cite web|url=http://www.grida.no/climate/ipcc_tar/wg1/233.htm |title=Climate Change 2001: The Scientific Basis |publisher=Grida.no |access-date=19 August 2011| archive-url= https://web.archive.org/web/20110629180154/http://www.grida.no/climate/ipcc_tar/wg1/233.htm| archive-date= 29 June 2011<!--Added by DASHBot-->}}</ref> Black carbon is a bigger cause of the melting of the polar ice cap in the Arctic than carbon dioxide due to its effect on the albedo.<ref>James Hansen & Larissa Nazarenko, ''Soot Climate Forcing Via Snow and Ice Albedos'', 101 Proc. of the Nat'l. Acad. of Sci. 423 (13 January 2004) ("The efficacy of this forcing is »2 (i.e., for a given forcing it is twice as effective as CO<sub>2</sub> in altering global surface air temperature)"); ''compare'' Zender Testimony, ''supra'' note 7, at 4 (figure 3); See J. Hansen & L. Nazarenko, ''supra'' note 18, at 426. ("The efficacy for changes of Arctic sea ice albedo is >3. In additional runs not shown here, we found that the efficacy of albedo changes in Antarctica is also >3."); ''See also'' Flanner, M.G., C.S. Zender, J.T. Randerson, and P.J. Rasch, ''Present-day climate forcing and response from black carbon in snow'', 112 J. GEOPHYS. RES. D11202 (2007) ("The forcing is maximum coincidentally with snowmelt onset, triggering strong snow-albedo feedback in local springtime. Consequently, the "efficacy" of black carbon/snow forcing is more than three times greater than forcing by CO<sub>2</sub>.").</ref>{{Failed verification|date=January 2020}}