Polar amplification

An observation-based study related to Arctic amplification was published in 1969 by Mikhail Budyko,{{cite journal|volume=21|issue=5|doi=10.3402/tellusa.v21i5.10109|title=The effect of solar radiation variations on the climate of the Earth|year=1969|first=M.I.|last=Budyko|s2cid=21745322|journal=Tellus|pages=611–9|bibcode=1969Tell...21..611B|doi-access=free}} and the study conclusion has been summarized as "Sea ice loss affects Arctic temperatures through the surface albedo feedback."{{cite journal|url=https://link.springer.com/content/pdf/10.1007%2Fs00382-015-2489-1.pdf|title=Atmospheric impacts of sea ice decline in CO2 induced global warming|doi=10.1007/s00382-015-2489-1|year=2015|first1=Ivana|last1=Cvijanovic|first2=Ken|last2=Caldeira|journal=Climate Dynamics|pages=1173–86|volume=44|issue=5–6 |bibcode=2015ClDy...44.1173C|s2cid=106405448|doi-access=free}}{{cite web|url=http://www.yalescientific.org/2016/06/ice-in-action-sea-ice-at-the-north-pole-has-something-to-say-about-climate-change|title=Ice in Action: Sea ice at the North Pole has something to say about climate change|year=2016|work=YaleScientific}} The same year, a similar model was published by William D. Sellers.{{cite journal|title=A Global Climatic Model Based on the Energy Balance of the Earth-Atmosphere System|year=1969|doi=10.1175/1520-0450(1969)008<0392:AGCMBO>2.0.CO;2|first=William D.|last=Sellers|journal=Journal of Applied Meteorology|volume=8|issue=3|pages=392–400|bibcode=1969JApMe...8..392S |doi-access=free}} Both studies attracted significant attention since they hinted at the possibility for a runaway positive feedback within the global climate system.{{cite journal|title=Mikhail Budyko's (1920–2001) contributions to Global Climate Science: from heat balances to climate change and global ecology|year=2016|first=Jonathan D.|last=Oldfield|doi=10.1002/wcc.412|journal=Advanced Review|volume=7|issue=5|pages=682–692|doi-access=free|bibcode=2016WIRCC...7..682O }} In 1975, Manabe and Wetherald published the first somewhat plausible general circulation model that looked at the effects of an increase of greenhouse gas. Although confined to less than one-third of the globe, with a "swamp" ocean and only land surface at high latitudes, it showed an Arctic warming faster than the tropics (as have all subsequent models).{{cite journal|last1=Manabe|first1=Syukoro|last2=Wetherald|first2=Richard T.|title=The Effects of Doubling the CO2 Concentration on the Climate of a General Circulation Model|journal=Journal of the Atmospheric Sciences|date=1975|volume=32|issue=1|pages=3–15|doi=10.1175/1520-0469(1975)032<0003:TEODTC>2.0.CO;2 |doi-access=free|bibcode=1975JAtS...32....3M}}

Feedbacks associated with sea ice and snow cover are widely cited as one of the principal causes of terrestrial polar amplification.{{cite journal|vauthors = Hansen J, Sato M, Ruedy R|year=1997|title=Radiative forcing and climate response|journal=Journal of Geophysical Research: Atmospheres|volume=102|issue=D6|pages=6831–64|doi=10.1029/96jd03436|bibcode=1997JGR...102.6831H}}{{Cite journal|last1=Pistone|first1=Kristina|last2=Eisenman|first2=Ian|last3=Ramanathan|first3=Veerabhadran|s2cid=197572148|author-link2=Ian Eisenman|author-link3=Veerabhadran Ramanathan|date=2019|title=Radiative Heating of an Ice-Free Arctic Ocean|journal=Geophysical Research Letters|language=en|volume=46|issue=13|pages=7474–7480|doi=10.1029/2019GL082914|bibcode=2019GeoRL..46.7474P|url=https://escholarship.org/uc/item/678849wc}} These feedbacks are particularly noted in local polar amplification,{{Cite journal|last1=Bekryaev|first1=Roman V.|last2=Polyakov|first2=Igor V.|last3=Alexeev|first3=Vladimir A.|date=2010-07-15|title=Role of Polar Amplification in Long-Term Surface Air Temperature Variations and Modern Arctic Warming|journal=Journal of Climate|language=EN|volume=23|issue=14|pages=3888–3906|doi=10.1175/2010JCLI3297.1|bibcode=2010JCli...23.3888B|issn=0894-8755|doi-access=free}} although recent work has shown that the lapse rate feedback is likely equally important to the ice-albedo feedback for Arctic amplification. Supporting this idea, large-scale amplification is also observed in model worlds with no ice or snow.{{cite journal|vauthors = Alexeev VA, Langen PL, Bates JR|year=2005|title=Polar amplification of surface warming on an aquaplanet in "ghost forcing" experiments without sea ice feedbacks|journal=Climate Dynamics|volume=24|issue=7–8|pages=655–666|doi=10.1007/s00382-005-0018-3|bibcode=2005ClDy...24..655A|s2cid=129600712}} It appears to arise both from a (possibly transient) intensification of poleward heat transport and more directly from changes in the local net radiation balance. Local radiation balance is crucial because an overall decrease in outgoing longwave radiation will produce a larger relative increase in net radiation near the poles than near the equator. Thus, between the lapse rate feedback and changes in the local radiation balance, much of polar amplification can be attributed to changes in outgoing longwave radiation.{{Cite journal|last1=Payne|first1=Ashley E.|last2=Jansen|first2=Malte F.|last3=Cronin|first3=Timothy W.|date=2015|title=Conceptual model analysis of the influence of temperature feedbacks on polar amplification|journal=Geophysical Research Letters|language=en|volume=42|issue=21|pages=9561–9570|doi=10.1002/2015GL065889|bibcode=2015GeoRL..42.9561P|issn=1944-8007|doi-access=free}} This is especially true for the Arctic, whereas the elevated terrain in Antarctica limits the influence of the lapse rate feedback.{{cite journal |last1=Hahn |first1=L. C. |last2=Armour |first2=K. C. |last3=Battisti |first3=D. S. |last4=Donohoe |first4=A. |last5=Pauling |first5=A. G. |last6=Bitz |first6=C. M. |title=Antarctic Elevation Drives Hemispheric Asymmetry in Polar Lapse Rate Climatology and Feedback |journal=Geophysical Research Letters |date=28 August 2020 |volume=47 |issue=16 |doi=10.1029/2020GL088965|bibcode=2020GeoRL..4788965H |s2cid=222009674 |url=http://eartharxiv.org/6fbjk/ |doi-access=free }}

Some examples of climate system feedbacks thought to contribute to recent polar amplification include the reduction of snow cover and sea ice, changes in atmospheric and ocean circulation, the presence of anthropogenic soot in the Arctic environment, and increases in cloud cover and water vapor.{{cite web|url=http://www.climatechange2013.org/images/report/WG1AR5_Chapter11_FINAL.pdf|title=IPCC AR5 – Near-term Climate Change: Projections and Predictability (Chapter 11 / page 983 )|year=2013}} CO₂ forcing has also been attributed to polar amplification. Most studies connect sea ice changes to polar amplification. Both ice extent and thickness impact polar amplification. Climate models with smaller baseline sea ice extent and thinner sea ice coverage exhibit stronger polar amplification.{{Cite journal|last1=Holland|first1=M. M.|last2=Bitz|first2=C. M.|date=2003-09-01|title=Polar amplification of climate change in coupled models|journal=Climate Dynamics|language=en|volume=21|issue=3|pages=221–232|doi=10.1007/s00382-003-0332-6|bibcode=2003ClDy...21..221H|s2cid=17003665|issn=1432-0894}} Some models of modern climate exhibit Arctic amplification without changes in snow and ice cover.{{cite journal|title=Arctic amplification dominated by temperature feedbacks in contemporary climate models|doi=10.1038/ngeo2071|journal=Nature Geoscience|volume=7|pages=181–4|first1=Felix|last1=Pithan|first2=Thorsten|last2=Mauritsen|s2cid=140616811|date=February 2, 2014|issue=3|bibcode=2014NatGe...7..181P}}

The individual processes contributing to polar warming are critical to understanding climate sensitivity.{{cite journal | last1=Taylor | first1=Patrick C. | last2=Cai | first2=Ming | last3=Hu | first3=Aixue | last4=Meehl | first4=Jerry | last5=Washington | first5=Warren | last6=Zhang | first6=Guang J. | title=A Decomposition of Feedback Contributions to Polar Warming Amplification | journal=Journal of Climate | publisher=American Meteorological Society | volume=26 | issue=18 | date=2013-09-09 | issn=0894-8755 | doi=10.1175/jcli-d-12-00696.1 | pages=7023–7043 |bibcode=2013JCli...26.7023T| doi-access=free }} Polar warming also affects many ecosystems, including marine and terrestrial ecosystems, climate systems, and human populations.{{Cite journal|last1=Stuecker|first1=Malte F.|last2=Bitz|first2=Cecilia M.|last3=Armour|first3=Kyle C.|last4=Proistosescu|first4=Cristian|last5=Kang|first5=Sarah M.|last6=Xie|first6=Shang Ping|last7=Kim|first7=Doyeon|last8=McGregor|first8=Shayne|last9=Zhang|first9=Wenjun|last10=Zhao|first10=Sen|last11=Cai|first11=Wenju|date=December 2018|title=Polar amplification dominated by local forcing and feedbacks|url=https://www.nature.com/articles/s41558-018-0339-y|journal=Nature Climate Change|language=en|volume=8|issue=12|pages=1076–1081|doi=10.1038/s41558-018-0339-y|bibcode=2018NatCC...8.1076S|s2cid=92195853|issn=1758-6798}} Polar amplification is largely driven by local polar processes with hardly any remote forcing, whereas polar warming is regulated by tropical and midlatitude forcing. These impacts of polar amplification have led to continuous research in the face of global warming.

It has been estimated that 70% of global wind energy is transferred to the ocean and takes place within the Antarctic Circumpolar Current (ACC). Eventually, upwelling due to wind-stress transports cold Antarctic waters through the Atlantic surface current, while warming them over the equator, and into the Arctic environment. This is especially noticed in high latitudes. Thus, warming in the Arctic depends on the efficiency of the global ocean transport and plays a role in the polar see-saw effect.{{cite journal|journal=Geophysical Research Letters|date=February 3, 2010|url=http://www.leif.org/EOS/2010GL042793.pdf|author1=Petr Chylek |author2=Chris K. Folland |author3=Glen Lesins |author4=Manvendra K. Dubey |title=Twentieth century bipolar seesaw of the Arctic and Antarctic surface air temperatures|volume=12|issue=8|pages=4015–22|doi=10.1029/2010GL042793|bibcode=2010GeoRL..37.8703C|s2cid=18491097 |access-date=May 1, 2014|archive-url=https://web.archive.org/web/20140220051308/http://www.leif.org/EOS/2010GL042793.pdf|archive-date=February 20, 2014}}

Decreased oxygen and low-pH during La Niña are processes that correlate with decreased primary production and a more pronounced poleward flow of ocean currents.{{cite journal|journal=Geophysical Research Letters|date=November 23, 2011|author1=Sung Hyun Nam |author2=Hey-Jin Kim |author3=Uwe Send |s2cid=55150106|title=Amplification of hypoxic and acidic events by La Niña conditions on the continental shelf off California|volume=83|issue=22|pages=L22602|doi=10.1029/2011GL049549|bibcode=2011GeoRL..3822602N|doi-access=free}} It has been proposed that the mechanism of increased Arctic surface air temperature anomalies during La Niña periods of ENSO may be attributed to the Tropically Excited Arctic Warming Mechanism (TEAM), when Rossby waves propagate more poleward, leading to wave dynamics and an increase in downward infrared radiation.{{cite journal|journal=Journal of Climate|date=June 2012|author=Sukyoung Lee |author-link1=Sukyoung Lee|s2cid=91176052|title=Testing of the Tropically Excited Arctic Warming Mechanism (TEAM) with Traditional El Niño and La Niña|volume=25|issue=12|pages=4015–22|doi=10.1175/JCLI-D-12-00055.1|bibcode=2012JCli...25.4015L|doi-access=free}}

Polar amplification is quantified in terms of a polar amplification factor, generally defined as the ratio of some change in a polar temperature to a corresponding change in a broader average temperature:

:$\{\; PAF\; \}=\{\backslash Delta\{T\}\_\{p\}\backslash over\backslash Delta\backslash overline\{T\}\}${{space}}{{space}},

where $\backslash Delta\{T\}\_\{p\}$ is a change in polar temperature and $\backslash Delta\backslash overline\{T\}${{space}}{{space}} is, for example, a corresponding change in a global mean temperature.

Common implementations{{cite journal |author=Masson-Delmotte, V. |author2=M. Kageyama |author3=P. Braconnot |author4=S. Charbit |author5=G. Krinner |author6=C. Ritz |author7=E. Guilyardi |title=Past and future polar amplification of climate change: climate model intercomparisons and ice-core constraints |journal=Climate Dynamics|volume=26|number=5|date=2006|pages=513–529|doi=10.1007/s00382-005-0081-9|display-authors=etal|bibcode=2006ClDy...26..513M |s2cid=2370836}}{{cite journal |author=James Hansen |author2=Makiko Sato |author3=Gary Russell |author4=Pushker Kharecha |date=September 2013|title=Climate sensitivity, sea level and atmospheric carbon dioxide |journal=Philosophical Transactions of the Royal Society A |volume=371|doi=10.1098/rsta.2012.0294 |doi-access=free |pmid=24043864 |issue=2001 |pmc=3785813|arxiv=1211.4846|bibcode=2013RSPTA.37120294H }} define the temperature changes directly as the anomalies in surface air temperature relative to a recent reference interval (typically 30 years). Others have used the ratio of the variances of surface air temperature over an extended interval.{{cite journal|author=Kobashi, T. |author2=Shindell, D. T. |author3=Kodera, K. |author4=Box, J. E. |author5=Nakaegawa, T. |author6=Kawamura, K. |date=2013|title=On the origin of multidecadal to centennial Greenland temperature anomalies over the past 800 yr|journal=Climate of the Past|volume=9|issue=2|pages=583–596|doi=10.5194/cp-9-583-2013|bibcode=2013CliPa...9..583K |doi-access=free|hdl=2060/20150002680|hdl-access=free}}

File:AntarcticaTemps3 1957-2006.png (left) have greatly exceeded the global average; East Antarctica less so.]]

It is observed that Arctic and Antarctic warming commonly proceed out of phase because of orbital forcing, resulting in the so-called polar see-saw effect.{{cite journal|title=Mid-latitude interhemispheric hydrologic seesaw over the past 550,000 years|doi=10.1038/nature13076|author=Kyoung-nam Jo |author2=Kyung Sik Woo |author3=Sangheon Yi |author4=Dong Yoon Yang |author5=Hyoun Soo Lim |author6=Yongjin Wang |author7=Hai Cheng |author8=R. Lawrence Edwards |journal=Nature|volume=508|pages=378–382|date=March 30, 2014|issue=7496|pmid=24695222|bibcode=2014Natur.508..378J|s2cid=2096406}}

The glacial / interglacial cycles of the Pleistocene provide extensive palaeoclimate evidence of polar amplification, both from the Arctic and the Antarctic. In particular, the temperature rise since the last glacial maximum {{formatnum:20000}} years ago provides a clear picture. Proxy temperature records from the Arctic (Greenland) and from the Antarctic indicate polar amplification factors on the order of 2.0.

{{See also|Climate change in the Arctic}}

File:NORTH POLE Ice (19626661335).jpg

Suggested mechanisms leading to the observed Arctic amplification include Arctic sea ice decline (open water reflects less sunlight than sea ice), atmospheric heat transport from the equator to the Arctic,{{cite web|url=https://climate.nasa.gov/news/927/arctic-amplification|title=Arctic amplification|work=NASA|year=2013}} and the lapse rate feedback.{{cite journal |last1=Goosse |first1=Hugues |last2=Kay |first2=Jennifer E. |last3=Armour |first3=Kyle C. |last4=Bodas-Salcedo |first4=Alejandro |last5=Chepfer |first5=Helene |last6=Docquier |first6=David |last7=Jonko |first7=Alexandra |last8=Kushner |first8=Paul J. |last9=Lecomte |first9=Olivier |last10=Massonnet |first10=François |last11=Park |first11=Hyo-Seok |last12=Pithan |first12=Felix |last13=Svensson |first13=Gunilla |last14=Vancoppenolle |first14=Martin |title=Quantifying climate feedbacks in polar regions |journal=Nature Communications |date=December 2018 |volume=9 |issue=1 |page=1919 |doi=10.1038/s41467-018-04173-0|pmid=29765038 |pmc=5953926 |bibcode=2018NatCo...9.1919G |doi-access=free }}

The Arctic was historically described as warming twice as fast as the global average,{{Cite news|url=https://insideclimatenews.org/news/02022018/cold-weather-polar-vortex-jet-stream-explained-global-warming-arctic-ice-climate-change|title=Polar Vortex: How the Jet Stream and Climate Change Bring on Cold Snaps|date=2018-02-02|work=InsideClimate News|access-date=2018-11-24|language=en}} but this estimate was based on older observations which missed the more recent acceleration. By 2021, enough data was available to show that the Arctic had warmed three times as fast as the globe - 3.1°C between 1971 and 2019, as opposed to the global warming of 1°C over the same period.{{cite web |date=2021-05-20 |title=Arctic warming three times faster than the planet, report warns |url=https://phys.org/news/2021-05-arctic-faster-planet.html |website=Phys.org |language=en |access-date=6 October 2022}} Moreover, this estimate defines the Arctic as everything above 60th parallel north, or a full third of the Northern Hemisphere: in 2021–2022, it was found that since 1979, the warming within the Arctic Circle itself (above the 66th parallel) has been nearly four times faster than the global average.{{Cite journal |last1=Rantanen |first1=Mika |last2=Karpechko |first2=Alexey Yu |last3=Lipponen |first3=Antti |last4=Nordling |first4=Kalle |last5=Hyvärinen |first5=Otto |last6=Ruosteenoja |first6=Kimmo |last7=Vihma |first7=Timo |last8=Laaksonen |first8=Ari |date=11 August 2022 |title=The Arctic has warmed nearly four times faster than the globe since 1979 |journal=Communications Earth & Environment |language=en |volume=3 |issue=1 |page=168 |doi=10.1038/s43247-022-00498-3 |s2cid=251498876 |issn=2662-4435|doi-access=free |bibcode=2022ComEE...3..168R |hdl=11250/3115996 |hdl-access=free }}{{cite web |date=2021-12-14 |title=The Arctic is warming four times faster than the rest of the world |url=https://www.science.org/content/article/arctic-warming-four-times-faster-rest-world |language=en |access-date=6 October 2022}} Within the Arctic Circle itself, even greater Arctic amplification occurs in the Barents Sea area, with hotspots around West Spitsbergen Current: weather stations located on its path record decadal warming up to seven times faster than the global average.{{Cite journal |last1=Isaksen |first1=Ketil |last2=Nordli |first2=Øyvind |display-authors=etal |date=15 June 2022 |title=Exceptional warming over the Barents area |journal=Scientific Reports |language=en |volume=12 |issue=1 |page=9371 |doi=10.1038/s41598-022-13568-5 |pmid=35705593 |pmc=9200822 |s2cid=249710630 |doi-access=free |bibcode=2022NatSR..12.9371I }}{{cite web |date=2022-06-15 |title=New data reveals extraordinary global heating in the Arctic |author=Damian Carrington |url=https://www.theguardian.com/environment/2022/jun/15/new-data-reveals-extraordinary-global-heating-in-the-arctic |website=The Guardian |language=en |access-date=7 October 2022}} This has fuelled concerns that unlike the rest of the Arctic sea ice, ice cover in the Barents Sea may permanently disappear even around 1.5 degrees of global warming.{{Cite journal |last1=Armstrong McKay |first1=David|last2=Abrams |first2=Jesse |last3=Winkelmann |first3=Ricarda |last4=Sakschewski |first4=Boris |last5=Loriani |first5=Sina |last6=Fetzer |first6=Ingo|last7=Cornell|first7=Sarah |last8=Rockström |first8=Johan |last9=Staal |first9=Arie |last10=Lenton |first10=Timothy |date=9 September 2022 |title=Exceeding 1.5°C global warming could trigger multiple climate tipping points |url=https://www.science.org/doi/10.1126/science.abn7950 |journal=Science |language=en |volume=377 |issue=6611 |pages=eabn7950 |doi=10.1126/science.abn7950 |pmid=36074831 |hdl=10871/131584 |s2cid=252161375 |issn=0036-8075|hdl-access=free }}{{Cite web |last=Armstrong McKay |first=David |date=9 September 2022 |title=Exceeding 1.5°C global warming could trigger multiple climate tipping points – paper explainer |url=https://climatetippingpoints.info/2022/09/09/climate-tipping-points-reassessment-explainer/ |access-date=2 October 2022 |website=climatetippingpoints.info |language=en}}

The acceleration of Arctic amplification has not been linear: a 2022 analysis found that it occurred in two sharp steps, with the former around 1986, and the latter after 2000.{{Cite journal |last1=Chylek |first1=Petr |last2=Folland |first2=Chris |last3=Klett |first3=James D. |last4=Wang |first4=Muyin |last5=Hengartner |first5=Nick |last6=Lesins |first6=Glen |last7=Dubey |first7=Manvendra K. |date=25 June 2022 |title=Annual Mean Arctic Amplification 1970–2020: Observed and Simulated by CMIP6 Climate Models |journal=Geophysical Research Letters |language=en |volume=49 |issue=13 |doi=10.1029/2022GL099371|s2cid=250097858 |doi-access=free |bibcode=2022GeoRL..4999371C }} The first acceleration is attributed to the increase in anthropogenic radiative forcing in the region, which is in turn likely connected to the reductions in stratospheric sulfur aerosols pollution in Europe in the 1980s in order to combat acid rain. Since sulphate aerosols have a cooling effect, their absence is likely to have increased Arctic temperatures by up to 0.5 degrees Celsius.{{Cite journal |last1=Acosta Navarro |first1=J.C. |last2=Varma |first2=V. |last3=Riipinen |first3=I. |last4=Seland |first4=Ø. |last5=Kirkevåg |first5=A. |last6=Struthers |first6=H. |last7=Iversen |first7=T. |last8=Hansson |first8=H.-C. |last9=Ekman |first9=A. M. L. |date=14 March 2016 |title=Amplification of Arctic warming by past air pollution reductions in Europe |url=https://www.nature.com/articles/ngeo2673 |journal=Nature Geoscience |language=en |volume=9|issue=4|pages=277–281|doi=10.1038/ngeo2673|bibcode=2016NatGe...9..277A}}{{cite news|url=https://www.washingtonpost.com/news/energy-environment/wp/2016/03/14/how-cleaner-air-could-actually-make-global-warming-worse|title=How cleaner air could actually make global warming worse|date=14 March 2016|newspaper=Washington Post|last=Harvey|first=C.}} The second acceleration has no known cause, which is why it did not show up in any climate models. It is likely to be an example of multi-decadal natural variability, like the suggested link between Arctic temperatures and Atlantic Multi-decadal Oscillation (AMO),{{cite journal|journal=Geophysical Research Letters|date=16 July 2009|first1=Petr|last1=Chylek|first2=Chris K.|last2=Folland|first3=Glen|last3=Lesins|first4=Manvendra K.|last4=Dubey|first5=Muyin|last5=Wang|title=Arctic air temperature change amplification and the Atlantic Multidecadal Oscillation |volume=36 |issue=14 |pages=L14801 |doi=10.1029/2009GL038777 |bibcode=2009GeoRL..3614801C |citeseerx=10.1.1.178.6926 |s2cid=14013240 }} in which case it can be expected to reverse in the future. However, even the first increase in Arctic amplification was only accurately simulated by a fraction of the current CMIP6 models.

{{See also|Rossby wave#Amplification of Rossby waves}}

{{excerpt|Jet stream#Longer-term climatic changes|paragraphs=1-8|file=yes}}

• Arctic dipole anomaly
• Arctic oscillation
• Climate of the Arctic
• Polar vortex
• Sudden stratospheric warming

{{Reflist|2}}

• {{cite web |last1=Turton |first1=Steve |title=Why is the Arctic warming faster than other parts of the world? Scientists explain |url=https://www.weforum.org/agenda/2021/06/climate-arctic-glacial-melt-rate |website=WEForum.org |publisher=World Economic Forum |archive-url=https://web.archive.org/web/20210603125701/https://www.weforum.org/agenda/2021/06/climate-arctic-glacial-melt-rate/ |archive-date=3 June 2021 |date=3 June 2021 |url-status=live }}

{{Global warming|state=collapsed}}

{{Climate oscillations|state=collapsed}}

Category:Arctic Ocean

Category:Climate change

Category:Environment of the Arctic

Category:Environment of Antarctica

Category:Arctic