State of the climate in 2020 (2024)

Blunden, J., Boyer, T., Dunn, R. J. H., Allen, J., Andersen, A., Hammer, G., Love-Brotak, S. E., Misch, D. J., Riddle, D. B., Veasey, S. W., Ades, M., Adler, R., Aldred, F., Allan, R. P., Allan, R., Anderson, J., Argüez, A., Arosio, C., Augustine, J. A., ... Zhu, Z. (2021). State of the climate in 2020. Bulletin of the American Meteorological Society, 102(8), 1-481. https://doi.org/10.1175/2021BAMSStateoftheClimate.1

Blunden, Jessica ; Boyer, T. ; Dunn, Robert J.H. et al. / State of the climate in 2020. In: Bulletin of the American Meteorological Society. 2021 ; Vol. 102, No. 8. pp. 1-481.

@article{c15f57ba006d466db7c8f1fe517d05b7,

title = "State of the climate in 2020",

abstract = "In 2020, the dominant greenhouse gases stored in Earth{\textquoteright}s atmosphere continued to increase. The annual global average carbon dioxide (CO2) concentration at Earth{\textquoteright}s surface was 412.5 ± 0.1 ppm, an increase of 2.5 ± 0.1 ppm over 2019, and the highest in the modern instrumental record and in ice core records dating back 800,000 years. While anthropogenic CO2 emissions were estimated to decrease around 6%–7% globally during the year due to reduced human activities during the COVID-19 pandemic, the reduction did not materially affect atmospheric CO2 accumulation as it is a relatively small change, less even than interannual variability driven by the terrestrial biosphere. The net global uptake of ~3.0 petagrams of anthropogenic carbon by oceans in 2020 was the highest in the 39-year record and almost 30% higher than the 1999–2019 average. Weak El Ni{\~n}o-like conditions in the eastern equatorial Pacific Ocean in early 2020 cooled and transitioned to a moderate La Ni{\~n}a later in the year. Even so, the annual global surface temperature across land and oceans was among the three highest in records dating to the mid- to late 1800s. In Europe, 17 countries reported record high annual mean temperatures, contributing to the warmest year on record for the European continent. Elsewhere, Japan, Mexico, and Seychelles also experienced record high annual mean temperatures. In the Caribbean, Aruba, Martinique, and St. Lucia reported their all-time monthly maximum temperatures. In the United States, Furnace Creek in Death Valley, California, reached 54.4°C on 16 August—the hottest temperature measured on Earth since 1931, pending confirmation. North of 60°N, the annual mean temperature over Arctic land areas was 2.1°C above the 1981–2010 average, the highest in the 121-year record. On 20 June, a temperature of 38°C was observed at Verkhoyansk, Russia (67.6°N), provisionally the highest temperature ever measured within the Arctic Circle. Near the opposite pole, an atmospheric river—a long, narrow region in the atmosphere that transports heat and moisture from sub-tropical and midlatitudes—brought extreme warmth from sub-tropical and midlatitudes to parts of Antarctica during austral summer. On 6 February, Esperanza Station recorded a temperature of 18.3°C, the highest temperature recorded on the continent, surpassing the previous record set in 2015 by 1.1°C. The warmth also led to the largest late-summer surface melt event in the 43-year record, affecting more than 50% of the Antarctic Peninsula. In August, daily sea ice extent in the waters surrounding Antarctica shifted from below to above average, marking the end of persistent below-average sea ice extent since austral spring 2016. In the Arctic, when sea ice reached its annual maximum extent in March, thin, first-year ice comprised ~70% of the ice; the thickest ice, which is usually more than four years old, had declined by more than 86% since 1985 to make up just 2% of total ice in 2020. When the minimum sea ice extent was reached in September, it was the second smallest except for 2012 in the 42-year satellite record. The Northern Sea Route along the Siberian coast was open for about 2.5 months, from late July through mid-October, compared to less than a month typically. Glaciers across the global cryosphere lost mass for the 33rd consecutive year, and permafrost temperatures continued to reach record highs at many high latitude and mountain locations. In the Northern Hemisphere, lakes froze three days later and thawed 5.5 days earlier on average. In Finland, the average duration of lake ice was 42 days shorter. Record high spring temperatures in central Siberia drove rapid snow melt that contributed to the lowest June snow cover extent across Eurasia in the 54-year record. As is typical, some areas around the world were notably dry in 2020 and some were notably wet. The Middle East experienced an extreme drought during autumn, with most places reporting no precipitation in October. In South America, the Bolivian lowlands suffered one of its most severe droughts on record during autumn. Drought also spanned the Chaco and Pantanal in Bolivia, Paraguay, and southern Brazil. The Paraguay River shrank to its lowest levels in half a century. A decadal “mega drought” in south-central Chile continued through its 11th year, with extreme conditions in the most populated areas. Argentina reported its driest year since 1995. In North America, drought continued to prevail in the West. The lack of moisture in drought-stricken regions often provide ideal conditions for fire. Total fire emissions in the western United States in 2020 were almost three times higher than the 2003–10 mean. The Arctic experienced its highest fire year in terms of carbon emitted into the atmosphere, surpassing the record set in 2019 by 34%, with most of the fires occurring in Arctic Asia. In the tropics, the Amazon saw its highest fire activity since 2012, while fire activity in tropical Asia—including Indonesia—was one of the lowest on record, related to wet conditions as La Ni{\~n}a evolved during the fire season. The 2020 Southwest Asian Monsoon season (June–September) was the wettest since 1981, also coincident with the emergence of La Ni{\~n}a. The Meiyu rainy season, which usually occurs between July and August over the Yangtze and Huaihe River Valleys of China, was extended by two months in 2020. The May–October total rainfall averaged over the area was the most since the start of the record in 1961. Associated severe flooding affected about 45.5 million people. A widespread desert locust infestation during 2019–20 impacted equatorial and northern East Africa, as heavy rains and prevailing winds were favorable for breeding and movement of swarms across Kenya, Ethiopia, northeastern Somalia, Uganda, South Sudan, and northern Tanzania. The massive infestation destroyed thousands of square kilometers of cropland and pasture lands, resulting in one million people in need of food aid in Ethiopia alone. Extremely heavy rains in April also triggered widespread flooding and landslides in Ethiopia, Somalia, Rwanda, and Burundi. The Lake Victoria region was the wettest in its 40-year record. Across the global oceans, the average ocean heat content reached a record high in 2020 and the sea surface temperature was the third highest on record, surpassed only by 2016 and 2019. Approximately 84% of the ocean surface experienced at least one marine heatwave (MHW) in 2020. For the second time in the past decade, a major MHW developed in the northeast Pacific, covering an area roughly six times the size of Alaska in September. Global mean sea level was record high for the ninth consecutive year, reaching 91.3 mm above the 1993 average when satellite measurements began, an increase of 3.5 mm over 2019. Melting of the Greenland Ice Sheet accounted for about 0.8 mm of the sea level rise, with an overall loss of 293 ± 66 gigatons of ice. A total of 102 named tropical storms were observed during the Northern and Southern Hemisphere storm seasons, well above the 1981–2010 average of 85. In the North Atlantic, a record 30 tropical cyclones formed, surpassing the previous record of 28 in 2005. Major Hurricanes Eta and Iota made landfall along the eastern coast of Nicaragua in nearly the same location within a two-week period, impacting over seven million people across Central America. In the western North Pacific, Super Typhoon Goni was the strongest tropical cyclone to make landfall in the historical record and led to the evacuation of almost 1 million people in the Philippines. Very Severe Cyclonic Storm Gati was the strongest recorded cyclone to make landfall over Somalia. Bosaso, in northeast Somalia, received 128 mm of rainfall in a 24-hour period, exceeding the city{\textquoteright}s average annual total of 100 mm. Above Earth{\textquoteright}s surface, the annual lower troposphere temperature equaled 2016 as the highest on record, while stratospheric temperatures continued to decline. In 2020, the stratospheric winter polar vortices in both hemispheres were unusually strong and stable. Between December 2019 and March 2020, the Arctic polar vortex was the strongest since the beginning of the satellite era, contributing to record low stratospheric ozone levels in the region that lasted into spring. The anomalously strong and persistent Antarctic polar vortex was linked to the longest-lived, and 12th-largest, ozone hole over the region, which lasted to the end of December.",

author = "Jessica Blunden and T. Boyer and Dunn, {Robert J.H.} and Jessicca Allen and Andrea Andersen and Gregory Hammer and Love-Brotak, {S. Elizabeth} and Misch, {Deborah J.} and Riddle, {Deborah B.} and Veasey, {Sara W.} and M. Ades and Robert Adler and F. Aldred and Allan, {Richard P.} and Rob Allan and J. Anderson and Anthony Arg{\"u}ez and C. Arosio and Augustine, {John A.} and C. Azorin-Molina and J. Barichivich and Beck, {H. E.} and Andreas Becker and Nicolas Bellouin and Angela Benedetti and Berry, {David I.} and Stephen Blenkinsop and Olivier Bock and X. Bodin and Bosilovich, {Michael G.} and Olivier Boucher and Buehler, {S. A.} and B. Calmettes and Laura Carrea and Laura Castia and Christiansen, {Hanne H.} and Christy, {John R.} and Chung, {E. S.} and Melanie Coldewey-Egbers and Cooper, {Owen R.} and Cornes, {Richard C.} and Curt Covey and Cretaux, {J. F.} and M. Crotwell and Davis, {Sean M.} and {de Jeu}, {Richard A.M.} and Doug Degenstein and R. Delaloye and {Di Girolamo}, Larry and Donat, {Markus G.} and Dorigo, {Wouter A.} and Imke Durre and Dutton, {Geoff S.} and Gregory Duveiller and Elkins, {James W.} and Fioletov, {Vitali E.} and Johannes Flemming and Foster, {Michael J.} and Frith, {Stacey M.} and Lucien Froidevaux and J. Garforth and Matthew Gentry and Nadine Gobron and Gupta, {S. K.} and S. Hahn and Leopold Haimberger and Hall, {Brad D.} and Ian Harris and Hemming, {D. L.} and M. Hirschi and Ho, {Shu Pen} and F. Hrbacek and Daan Hubert and Hurst, {Dale F.} and Antj Inness and K. Isaksen and John, {Viju O.} and Jones, {Philip D.} and Robert Junod and Kaiser, {J. W.} and V. Kaufmann and A. Kellerer-Pirklbauer and Kent, {Elizabeth C.} and R. Kidd and Hyungjun Kim and Z. Kipling and A. Koppa and Kraemer, {B. M.} and Kratz, {D. P.} and Xin Lan and Lantz, {Kathleen O.} and D. Lavers and Loeb, {Norman G.} and Diego Loyola and R. Madelon and Michael Mayer and McCabe, {M. F.} and McVicar, {Tim R.} and Mears, {Carl A.} and Merchant, {Christopher J.} and Miller, {John B.} and Miralles, {Diego G.} and L. Moesinger and Montzka, {Stephen A.} and Colin Morice and L. M{\"o}singer and Jens M{\"u}hle and Nicolas, {Julien P.} and Jeannette Noetzli and Ben Noll and J. O'Keefe and Osborn, {Tim J.} and T. Park and Pasik, {A. J.} and C. Pellet and Pelto, {Maury S.} and Perkins-Kirkpatrick, {S. E.} and G. Petron and Coda Phillips and S. Po-Chedley and L. Polvani and W. Preimesberger and Rains, {D. G.} and Randel, {W. J.} and Rayner, {Nick A.} and Samuel Remy and L. Ricciardulli and Richardson, {A. D.} and Robinson, {David A.} and Matthew Rodell and Rodriguez-Fernandez, {N. J.} and Rosenlof, {K. H.} and C. Roth and A. Rozanov and T. Rutishauser and Ahira Sanchez-Lugo and P. Sawaengphokhai and T. Scanlon and Verena Schenzinger and Schlegel, {R. W.} and S. Sharma and Lei Shi and Simmons, {Adrian J.} and Carolina Siso and Smith, {Sharon L.} and Soden, {B. J.} and Viktoria Sofieva and Sparks, {T. H.} and Stackhouse, {Paul W.} and Wolfgang Steinbrecht and Martin Stengel and Streletskiy, {Dimitri A.} and Sunny Sun-Mack and P. Tans and Thackeray, {S. J.} and E. Thibert and D. Tokuda and Kleareti Tourpali and Tye, {Mari R.} and {van der A}, Ronald and {van der Schalie}, Robin and {van der Schrier}, Gerard and {van der Vliet}, M. and {van der Werf}, {Guido R.} and A. Vance and Vernier, {Jean Paul} and Vimont, {Isaac J.} and Holger V{\"o}mel and Vose, {Russell S.} and Ray Wang and Markus Weber and David Wiese and Wilber, {Anne C.} and Wild, {Jeanette D.} and Willett, {Kate M.} and Takmeng Wong and Woolway, {R. Iestyn} and Xungang Yin and Guangyu Zhao and Lin Zhao and Xinjia Zhou and Ziemke, {Jerry R.} and Markus Ziese and Zotta, {R. M.} and Alin, {Simone R.} and Amaya, {Dillon J.} and Baringer, {Molly O.} and Peter Brandt and Carter, {Brendan R.} and Ivona Cetini{\'c} and Chambers, {Don P.} and Lijing Cheng and Collins, {Andrew U.} and Cathy Cosca and Ricardo Domingues and Shenfu Dong and Feely, {Richard A.} and Eleanor Frajka-Williams and Franz, {Bryan A.} and John Gilson and Gustavo Goni and Hamlington, {Benjamin D.} and Josefine Herrford and Hu, {Zeng Zhen} and Boyin Huang and Masayoshi Ishii and Svetlana Jevrejeva and Johnson, {Gregory C.} and Kennedy, {John J.} and Marion Kersal{\'e} and Killick, {Rachel E.} and Peter Landsch{\"u}tzer and Matthias Lankhorst and Eric Leuliette and Ricardo Locarnini and Rick Lumpkin and Lyman, {John M.} and Marra, {John J.} and Meinen, {Christopher S.} and Merrifield, {Mark A.} and Mitchum, {Gary T.} and Moat, {Ben I.} and Nerem, {R. Steven} and Perez, {Renellys C.} and Purkey, {Sarah G.} and James Reagan and Alejandra Sanchez-Franks and Scannell, {Hillary A.} and Claudia Schmid and Scott, {Joel P.} and Siegel, {David A.} and Smeed, {David A.} and William Sweet and Thompson, {Philip R.} and Tri{\~n}anes, {Joaquin A.} and Volkov, {Denis L.} and Rik Wanninkhof and Weller, {Robert A.} and Caihong Wen and Westberry, {Toby K.} and Widlansky, {Matthew J.} and Lisan Yu and Zhang, {Huai Min} and Becker, {Emily J.} and Bell, {Gerald D.} and Blake, {Eric S.} and Stephanie Bond and Bringas, {Francis G.} and Camargo, {Suzana J.} and Lin Chen and Coelho, {Caio A.S.} and Diamond, {Howard J.} and Goldenberg, {Stanley B.} and Nicolas Fauchereau and Halpert, {Michael S.} and Qiong He and Klotzbach, {Philip J.} and Knaff, {John A.} and Michelle L'Heureux and Landsea, {Chris W.} and Lin, {I. I.} and Lorrey, {Andrew M.} and Luo, {Jing Jia} and Kyle MacRitchie and Magee, {Andrew D.} and Pasch, {Richard J.} and Pezza, {Alexandre B.} and Matthew Rosencrans and Schreck, {Carl J.} and Tippett, {Michael K.} and Trewin, {Blair C.} and Truchelut, {Ryan E.} and Bin Wang and Hui Wang and Wood, {Kimberly M.} and Woolley, {John Mark} and Young, {Steven H.} and Ballinger, {Thomas J.} and Berner, {Logan T.} and Bernhard, {Germar H.} and Bhatt, {Uma S.} and Bjerke, {Jarle W.} and Box, {Jason E.} and R. Brown and John Cappelen and B. Decharme and C. Derksen and Dmitry Divine and Drozdov, {D. S.} and Druckenmiller, {Matthew L.} and {Elias Chereque}, A. and Epstein, {Howard E.} and Farquharson, {L. M.} and Farrell, {Sinead L.} and Fausto, {Robert S.} and Xavier Fettweis and Forbes, {Bruce C.} and Frost, {Gerald V.} and Emily Gargulinski and Sebastian Gerland and Goetz, {Scott J.} and Z. Grabinski and Groo{\ss}, {Jens Uwe} and Christian Haas and Edward Hanna and Inger Hanssen-Bauer and Stefan Hendricks and Holmes, {Robert M.} and Iolanda Ialongo and Piyush Jain and Bj{\o}rn Johnsen and L. Kaleschke and Kholodov, {A. L.} and Kim, {Seong Joong} and Korsgaard, {Niels J.} and Zachary Labe and Kaisa Lakkala and Lara, {Mark J.} and Bryant Loomis and K. Luojus and Macander, {Matthew J.} and Malkova, {G. V.} and Mankoff, {Kenneth D.} and Manney, {Gloria L.} and McClelland, {James W.} and Meier, {Walter N.} and Moon, {Twila A.} and Thomas Mote and L. Mudryk and Rolf M{\"u}ller and Nyland, {K. E.} and Overland, {James E.} and Olga Pavlova and Don Perovich and Alek Petty and Phoenix, {Gareth K.} and Raynolds, {Martha K.} and Reijmer, {C. H.} and Jacqueline Richter-Menge and Robert Ricker and Romanovsky, {Vladimir E.} and Lindsay Scott and Hazel Shapiro and Shiklomanov, {Alexander I.} and Shiklomanov, {Nikolai I.} and Smeets, {C. J.P.P.} and Amber Soja and Spencer, {Robert G.M.} and Sandy Starkweather and Anya Suslova and Tove Svendby and Tank, {Suzanne E.} and Marco Tedesco and Thoman, {Richard L.} and X. Tian-Kunze and Timmermans, {Mary Louise} and Hans T{\o}mmervik and Mikhail Tretiakov and Mark Tschudi and Sofia Vakhutinsky and {van As}, Dirk and {van de Wal}, {R. S.W.} and Sander Veraverbeke and Walker, {Donald A.} and Walsh, {John E.} and Muyin Wang and Melinda Webster and {\O}yvind Winton and K. Wood and Alison York and Robert Ziel and Susheel Adusumilli and Sandra Barreira and Deniz Bozkurt and Bushinsky, {Seth M.} and Clem, {Kyle R.} and Steve Colwell and Lawrence Coy and {De Laat}, Jos and {du Plessis}, {Marcel D.} and Fogt, {Ryan L.} and Annie Foppert and Fricker, {Helen Amanda} and Gardner, {Alex S.} and Gille, {Sarah T.} and Tessa Gorte and Bryan Johnson and Eric Keenan and Daemon Kennett and Keller, {Linda M.} and Kramarova, {Natalya A.} and Lazzara, {Matthew A.} and Lenaerts, {Jan T.M.} and Lieser, {Jan L.} and Zhi Li and Hongxing Liu and Long, {Craig S.} and Michael MacFerrin and Maclennan, {Michelle L.} and Massom, {Robert A.} and David Mikolajczyk and Lynn Montgomery and Mote, {Thomas L.} and Nash, {Eric R.} and Newman, {Paul A.} and Irina Petropavlovskikh and Michael Pitts and Phillip Reid and Rintoul, {Steven R.} and Santee, {Michelle L.} and Scambos, {Ted A.} and Shadwick, {Elizabeth H.} and Alessandro Silvano and Sharon Stammerjohn and Scott Stierle and Susan Strahan and Sutton, {Adrienne J.} and Sebastiaan Swart and Veronica Tamsitt and Bronte Tilbrook and Lei Wang and Williams, {Nancy L.} and Xiaojun Yuan and Alfaro, {Eric J.} and Alves, {Lincoln M.} and Amador, {Jorge A.} and B. Andrade and Francisco Argenalso and P. Asgarzadeh and Julian Baez and Reuben Barakiza and Bardin, {M. Yu} and Mikhail Bardin and Peter Bissolli and Oliver Bochni{\v c}ek and Brandon Bukunt and Blanca Calderon and Campbell, {Jayaka D.} and Elise Chandler and Ladislaus Chang'a and Cheng, {Vincent Y.S.} and Clarke, {Leonardo A.} and Kris Correa and Catalina Cortes and Felipe Costa and Cunha, {A. P.M.A.} and Mesut Demircan and Dhurmea, {K. R.} and A. Diawara and Sarah Diouf and Dashkhuu Dulamsuren and M. ElKharrim and Espinoza, {Jhan Carlo} and A. Fazl-Kazem and Chris Fenimore and Steven Fuhrman and Catherine Ganter and Karin Gleason and Guard, {Charles P.} and Samson Hagos and Mizuki Hanafusa and Hasannezhad, {H. R.} and Heim, {Richard R.} and Hidalgo, {Hugo G.} and Ijampy, {J. A.} and Im, {Gyo Soon} and Joseph, {Annie C.} and G. Jumaux and Kabidi, {K. R.} and Kamsu-Tamo, {P. H.} and John Kennedy and Valentina Khan and Khiem, {Mai Van} and Philemon King'uza and Korshunova, {Natalia N.} and Kruger, {A. C.} and M{\'o}nika Lakatos and Lam, {Hoang Phuc} and Lander, {Mark A.} and Waldo Lavado-Casimiro and Lee, {Tsz Cheung} and Leung, {Kinson H.Y.} and Tim Li and Gregor Macara and Jostein Mamen and Marengo, {Jos{\'e} A.} and Charlotte McBride and Ademe Mekonnen and Noelia Misevicius and Aurel Moise and Jorge Molina-Carpio and Natali Mora and Mostafa, {Awatif E.} and Habiba Mtongori and Charles Mutai and O. Ndiaye and Nieto, {Juan Jos{\'e}} and Latifa Nyembo and Patricia Nying'uro and Xiao Pan and {Pascual Ram{\'i}rez}, Reynaldo and David Phillips and Brad Pugh and Madhavan Rajeevan and Rakotonirina, {M. L.} and Ramos, {Andrea M.} and M. Robjhon and {Rodriguez Camino}, Ernesto and {Rodriguez Guisado}, Esteban and Josyane Ronchail and Benjamin R{\"o}sner and Roberto Salinas and Ahira S{\'a}nchez-Lugo and Hirotaka Sato and Hitoshi Sato and Amal Sayouri and Joseph Sebaziga and Serhat Sensoy and Sandra Spillane and Katja Trachte and F. Sima and Adam Smith and Spence, {Jacqueline M.} and Sreejith, {O. P.} and Srivastava, {A. K.} and Stella, {Jos{\'e} L.} and Stephenson, {Kimberly A.} and Stephenson, {Tannecia S.} and S. Supari and Sahar Tajbakhsh-Mosalman and Gerard Tamar and Taylor, {Michael A.} and Asaminew Teshome and Thiaw, {Wassila M.} and Skie Tobin and Trotman, {Adrian R.} and {Van Meerbeeck}, {Cedric J.} and A. Vazifeh and Shunya Wakamatsu and Wei Wang and Fei Xin and F. Zeng and Peiqun Zhang and Zhiwei Zhu",

note = "Publisher Copyright: {\textcopyright} 2021 American Meteorological Society.",

year = "2021",

month = aug,

doi = "10.1175/2021BAMSStateoftheClimate.1",

language = "English",

volume = "102",

pages = "1--481",

journal = "Bulletin of the American Meteorological Society",

issn = "0003-0007",

number = "8",

}

State of the climate in 2020. / Blunden, Jessica; Boyer, T.; Dunn, Robert J.H. et al.
In: Bulletin of the American Meteorological Society, Vol. 102, No. 8, 08.2021, p. 1-481.

Research output: Contribution to journal › Review article › peer-review

TY - JOUR

T1 - State of the climate in 2020

AU - Blunden, Jessica

AU - Boyer, T.

AU - Dunn, Robert J.H.

AU - Allen, Jessicca

AU - Andersen, Andrea

AU - Hammer, Gregory

AU - Love-Brotak, S. Elizabeth

AU - Misch, Deborah J.

AU - Riddle, Deborah B.

AU - Veasey, Sara W.

AU - Ades, M.

AU - Adler, Robert

AU - Aldred, F.

AU - Allan, Richard P.

AU - Allan, Rob

AU - Anderson, J.

AU - Argüez, Anthony

AU - Arosio, C.

AU - Augustine, John A.

AU - Azorin-Molina, C.

AU - Barichivich, J.

AU - Beck, H. E.

AU - Becker, Andreas

AU - Bellouin, Nicolas

AU - Benedetti, Angela

AU - Berry, David I.

AU - Blenkinsop, Stephen

AU - Bock, Olivier

AU - Bodin, X.

AU - Bosilovich, Michael G.

AU - Boucher, Olivier

AU - Buehler, S. A.

AU - Calmettes, B.

AU - Carrea, Laura

AU - Castia, Laura

AU - Christiansen, Hanne H.

AU - Christy, John R.

AU - Chung, E. S.

AU - Coldewey-Egbers, Melanie

AU - Cooper, Owen R.

AU - Cornes, Richard C.

AU - Covey, Curt

AU - Cretaux, J. F.

AU - Crotwell, M.

AU - Davis, Sean M.

AU - de Jeu, Richard A.M.

AU - Degenstein, Doug

AU - Delaloye, R.

AU - Di Girolamo, Larry

AU - Donat, Markus G.

AU - Dorigo, Wouter A.

AU - Durre, Imke

AU - Dutton, Geoff S.

AU - Duveiller, Gregory

AU - Elkins, James W.

AU - Fioletov, Vitali E.

AU - Flemming, Johannes

AU - Foster, Michael J.

AU - Frith, Stacey M.

AU - Froidevaux, Lucien

AU - Garforth, J.

AU - Gentry, Matthew

AU - Gobron, Nadine

AU - Gupta, S. K.

AU - Hahn, S.

AU - Haimberger, Leopold

AU - Hall, Brad D.

AU - Harris, Ian

AU - Hemming, D. L.

AU - Hirschi, M.

AU - Ho, Shu Pen

AU - Hrbacek, F.

AU - Hubert, Daan

AU - Hurst, Dale F.

AU - Inness, Antj

AU - Isaksen, K.

AU - John, Viju O.

AU - Jones, Philip D.

AU - Junod, Robert

AU - Kaiser, J. W.

AU - Kaufmann, V.

AU - Kellerer-Pirklbauer, A.

AU - Kent, Elizabeth C.

AU - Kidd, R.

AU - Kim, Hyungjun

AU - Kipling, Z.

AU - Koppa, A.

AU - Kraemer, B. M.

AU - Kratz, D. P.

AU - Lan, Xin

AU - Lantz, Kathleen O.

AU - Lavers, D.

AU - Loeb, Norman G.

AU - Loyola, Diego

AU - Madelon, R.

AU - Mayer, Michael

AU - McCabe, M. F.

AU - McVicar, Tim R.

AU - Mears, Carl A.

AU - Merchant, Christopher J.

AU - Miller, John B.

AU - Miralles, Diego G.

AU - Moesinger, L.

AU - Montzka, Stephen A.

AU - Morice, Colin

AU - Mösinger, L.

AU - Mühle, Jens

AU - Nicolas, Julien P.

AU - Noetzli, Jeannette

AU - Noll, Ben

AU - O'Keefe, J.

AU - Osborn, Tim J.

AU - Park, T.

AU - Pasik, A. J.

AU - Pellet, C.

AU - Pelto, Maury S.

AU - Perkins-Kirkpatrick, S. E.

AU - Petron, G.

AU - Phillips, Coda

AU - Po-Chedley, S.

AU - Polvani, L.

AU - Preimesberger, W.

AU - Rains, D. G.

AU - Randel, W. J.

AU - Rayner, Nick A.

AU - Remy, Samuel

AU - Ricciardulli, L.

AU - Richardson, A. D.

AU - Robinson, David A.

AU - Rodell, Matthew

AU - Rodriguez-Fernandez, N. J.

AU - Rosenlof, K. H.

AU - Roth, C.

AU - Rozanov, A.

AU - Rutishauser, T.

AU - Sanchez-Lugo, Ahira

AU - Sawaengphokhai, P.

AU - Scanlon, T.

AU - Schenzinger, Verena

AU - Schlegel, R. W.

AU - Sharma, S.

AU - Shi, Lei

AU - Simmons, Adrian J.

AU - Siso, Carolina

AU - Smith, Sharon L.

AU - Soden, B. J.

AU - Sofieva, Viktoria

AU - Sparks, T. H.

AU - Stackhouse, Paul W.

AU - Steinbrecht, Wolfgang

AU - Stengel, Martin

AU - Streletskiy, Dimitri A.

AU - Sun-Mack, Sunny

AU - Tans, P.

AU - Thackeray, S. J.

AU - Thibert, E.

AU - Tokuda, D.

AU - Tourpali, Kleareti

AU - Tye, Mari R.

AU - van der A, Ronald

AU - van der Schalie, Robin

AU - van der Schrier, Gerard

AU - van der Vliet, M.

AU - van der Werf, Guido R.

AU - Vance, A.

AU - Vernier, Jean Paul

AU - Vimont, Isaac J.

AU - Vömel, Holger

AU - Vose, Russell S.

AU - Wang, Ray

AU - Weber, Markus

AU - Wiese, David

AU - Wilber, Anne C.

AU - Wild, Jeanette D.

AU - Willett, Kate M.

AU - Wong, Takmeng

AU - Woolway, R. Iestyn

AU - Yin, Xungang

AU - Zhao, Guangyu

AU - Zhao, Lin

AU - Zhou, Xinjia

AU - Ziemke, Jerry R.

AU - Ziese, Markus

AU - Zotta, R. M.

AU - Alin, Simone R.

AU - Amaya, Dillon J.

AU - Baringer, Molly O.

AU - Brandt, Peter

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AU - Sato, Hirotaka

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AU - Zhang, Peiqun

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N1 - Publisher Copyright:© 2021 American Meteorological Society.

PY - 2021/8

Y1 - 2021/8

N2 - In 2020, the dominant greenhouse gases stored in Earth’s atmosphere continued to increase. The annual global average carbon dioxide (CO2) concentration at Earth’s surface was 412.5 ± 0.1 ppm, an increase of 2.5 ± 0.1 ppm over 2019, and the highest in the modern instrumental record and in ice core records dating back 800,000 years. While anthropogenic CO2 emissions were estimated to decrease around 6%–7% globally during the year due to reduced human activities during the COVID-19 pandemic, the reduction did not materially affect atmospheric CO2 accumulation as it is a relatively small change, less even than interannual variability driven by the terrestrial biosphere. The net global uptake of ~3.0 petagrams of anthropogenic carbon by oceans in 2020 was the highest in the 39-year record and almost 30% higher than the 1999–2019 average. Weak El Niño-like conditions in the eastern equatorial Pacific Ocean in early 2020 cooled and transitioned to a moderate La Niña later in the year. Even so, the annual global surface temperature across land and oceans was among the three highest in records dating to the mid- to late 1800s. In Europe, 17 countries reported record high annual mean temperatures, contributing to the warmest year on record for the European continent. Elsewhere, Japan, Mexico, and Seychelles also experienced record high annual mean temperatures. In the Caribbean, Aruba, Martinique, and St. Lucia reported their all-time monthly maximum temperatures. In the United States, Furnace Creek in Death Valley, California, reached 54.4°C on 16 August—the hottest temperature measured on Earth since 1931, pending confirmation. North of 60°N, the annual mean temperature over Arctic land areas was 2.1°C above the 1981–2010 average, the highest in the 121-year record. On 20 June, a temperature of 38°C was observed at Verkhoyansk, Russia (67.6°N), provisionally the highest temperature ever measured within the Arctic Circle. Near the opposite pole, an atmospheric river—a long, narrow region in the atmosphere that transports heat and moisture from sub-tropical and midlatitudes—brought extreme warmth from sub-tropical and midlatitudes to parts of Antarctica during austral summer. On 6 February, Esperanza Station recorded a temperature of 18.3°C, the highest temperature recorded on the continent, surpassing the previous record set in 2015 by 1.1°C. The warmth also led to the largest late-summer surface melt event in the 43-year record, affecting more than 50% of the Antarctic Peninsula. In August, daily sea ice extent in the waters surrounding Antarctica shifted from below to above average, marking the end of persistent below-average sea ice extent since austral spring 2016. In the Arctic, when sea ice reached its annual maximum extent in March, thin, first-year ice comprised ~70% of the ice; the thickest ice, which is usually more than four years old, had declined by more than 86% since 1985 to make up just 2% of total ice in 2020. When the minimum sea ice extent was reached in September, it was the second smallest except for 2012 in the 42-year satellite record. The Northern Sea Route along the Siberian coast was open for about 2.5 months, from late July through mid-October, compared to less than a month typically. Glaciers across the global cryosphere lost mass for the 33rd consecutive year, and permafrost temperatures continued to reach record highs at many high latitude and mountain locations. In the Northern Hemisphere, lakes froze three days later and thawed 5.5 days earlier on average. In Finland, the average duration of lake ice was 42 days shorter. Record high spring temperatures in central Siberia drove rapid snow melt that contributed to the lowest June snow cover extent across Eurasia in the 54-year record. As is typical, some areas around the world were notably dry in 2020 and some were notably wet. The Middle East experienced an extreme drought during autumn, with most places reporting no precipitation in October. In South America, the Bolivian lowlands suffered one of its most severe droughts on record during autumn. Drought also spanned the Chaco and Pantanal in Bolivia, Paraguay, and southern Brazil. The Paraguay River shrank to its lowest levels in half a century. A decadal “mega drought” in south-central Chile continued through its 11th year, with extreme conditions in the most populated areas. Argentina reported its driest year since 1995. In North America, drought continued to prevail in the West. The lack of moisture in drought-stricken regions often provide ideal conditions for fire. Total fire emissions in the western United States in 2020 were almost three times higher than the 2003–10 mean. The Arctic experienced its highest fire year in terms of carbon emitted into the atmosphere, surpassing the record set in 2019 by 34%, with most of the fires occurring in Arctic Asia. In the tropics, the Amazon saw its highest fire activity since 2012, while fire activity in tropical Asia—including Indonesia—was one of the lowest on record, related to wet conditions as La Niña evolved during the fire season. The 2020 Southwest Asian Monsoon season (June–September) was the wettest since 1981, also coincident with the emergence of La Niña. The Meiyu rainy season, which usually occurs between July and August over the Yangtze and Huaihe River Valleys of China, was extended by two months in 2020. The May–October total rainfall averaged over the area was the most since the start of the record in 1961. Associated severe flooding affected about 45.5 million people. A widespread desert locust infestation during 2019–20 impacted equatorial and northern East Africa, as heavy rains and prevailing winds were favorable for breeding and movement of swarms across Kenya, Ethiopia, northeastern Somalia, Uganda, South Sudan, and northern Tanzania. The massive infestation destroyed thousands of square kilometers of cropland and pasture lands, resulting in one million people in need of food aid in Ethiopia alone. Extremely heavy rains in April also triggered widespread flooding and landslides in Ethiopia, Somalia, Rwanda, and Burundi. The Lake Victoria region was the wettest in its 40-year record. Across the global oceans, the average ocean heat content reached a record high in 2020 and the sea surface temperature was the third highest on record, surpassed only by 2016 and 2019. Approximately 84% of the ocean surface experienced at least one marine heatwave (MHW) in 2020. For the second time in the past decade, a major MHW developed in the northeast Pacific, covering an area roughly six times the size of Alaska in September. Global mean sea level was record high for the ninth consecutive year, reaching 91.3 mm above the 1993 average when satellite measurements began, an increase of 3.5 mm over 2019. Melting of the Greenland Ice Sheet accounted for about 0.8 mm of the sea level rise, with an overall loss of 293 ± 66 gigatons of ice. A total of 102 named tropical storms were observed during the Northern and Southern Hemisphere storm seasons, well above the 1981–2010 average of 85. In the North Atlantic, a record 30 tropical cyclones formed, surpassing the previous record of 28 in 2005. Major Hurricanes Eta and Iota made landfall along the eastern coast of Nicaragua in nearly the same location within a two-week period, impacting over seven million people across Central America. In the western North Pacific, Super Typhoon Goni was the strongest tropical cyclone to make landfall in the historical record and led to the evacuation of almost 1 million people in the Philippines. Very Severe Cyclonic Storm Gati was the strongest recorded cyclone to make landfall over Somalia. Bosaso, in northeast Somalia, received 128 mm of rainfall in a 24-hour period, exceeding the city’s average annual total of 100 mm. Above Earth’s surface, the annual lower troposphere temperature equaled 2016 as the highest on record, while stratospheric temperatures continued to decline. In 2020, the stratospheric winter polar vortices in both hemispheres were unusually strong and stable. Between December 2019 and March 2020, the Arctic polar vortex was the strongest since the beginning of the satellite era, contributing to record low stratospheric ozone levels in the region that lasted into spring. The anomalously strong and persistent Antarctic polar vortex was linked to the longest-lived, and 12th-largest, ozone hole over the region, which lasted to the end of December.

AB - In 2020, the dominant greenhouse gases stored in Earth’s atmosphere continued to increase. The annual global average carbon dioxide (CO2) concentration at Earth’s surface was 412.5 ± 0.1 ppm, an increase of 2.5 ± 0.1 ppm over 2019, and the highest in the modern instrumental record and in ice core records dating back 800,000 years. While anthropogenic CO2 emissions were estimated to decrease around 6%–7% globally during the year due to reduced human activities during the COVID-19 pandemic, the reduction did not materially affect atmospheric CO2 accumulation as it is a relatively small change, less even than interannual variability driven by the terrestrial biosphere. The net global uptake of ~3.0 petagrams of anthropogenic carbon by oceans in 2020 was the highest in the 39-year record and almost 30% higher than the 1999–2019 average. Weak El Niño-like conditions in the eastern equatorial Pacific Ocean in early 2020 cooled and transitioned to a moderate La Niña later in the year. Even so, the annual global surface temperature across land and oceans was among the three highest in records dating to the mid- to late 1800s. In Europe, 17 countries reported record high annual mean temperatures, contributing to the warmest year on record for the European continent. Elsewhere, Japan, Mexico, and Seychelles also experienced record high annual mean temperatures. In the Caribbean, Aruba, Martinique, and St. Lucia reported their all-time monthly maximum temperatures. In the United States, Furnace Creek in Death Valley, California, reached 54.4°C on 16 August—the hottest temperature measured on Earth since 1931, pending confirmation. North of 60°N, the annual mean temperature over Arctic land areas was 2.1°C above the 1981–2010 average, the highest in the 121-year record. On 20 June, a temperature of 38°C was observed at Verkhoyansk, Russia (67.6°N), provisionally the highest temperature ever measured within the Arctic Circle. Near the opposite pole, an atmospheric river—a long, narrow region in the atmosphere that transports heat and moisture from sub-tropical and midlatitudes—brought extreme warmth from sub-tropical and midlatitudes to parts of Antarctica during austral summer. On 6 February, Esperanza Station recorded a temperature of 18.3°C, the highest temperature recorded on the continent, surpassing the previous record set in 2015 by 1.1°C. The warmth also led to the largest late-summer surface melt event in the 43-year record, affecting more than 50% of the Antarctic Peninsula. In August, daily sea ice extent in the waters surrounding Antarctica shifted from below to above average, marking the end of persistent below-average sea ice extent since austral spring 2016. In the Arctic, when sea ice reached its annual maximum extent in March, thin, first-year ice comprised ~70% of the ice; the thickest ice, which is usually more than four years old, had declined by more than 86% since 1985 to make up just 2% of total ice in 2020. When the minimum sea ice extent was reached in September, it was the second smallest except for 2012 in the 42-year satellite record. The Northern Sea Route along the Siberian coast was open for about 2.5 months, from late July through mid-October, compared to less than a month typically. Glaciers across the global cryosphere lost mass for the 33rd consecutive year, and permafrost temperatures continued to reach record highs at many high latitude and mountain locations. In the Northern Hemisphere, lakes froze three days later and thawed 5.5 days earlier on average. In Finland, the average duration of lake ice was 42 days shorter. Record high spring temperatures in central Siberia drove rapid snow melt that contributed to the lowest June snow cover extent across Eurasia in the 54-year record. As is typical, some areas around the world were notably dry in 2020 and some were notably wet. The Middle East experienced an extreme drought during autumn, with most places reporting no precipitation in October. In South America, the Bolivian lowlands suffered one of its most severe droughts on record during autumn. Drought also spanned the Chaco and Pantanal in Bolivia, Paraguay, and southern Brazil. The Paraguay River shrank to its lowest levels in half a century. A decadal “mega drought” in south-central Chile continued through its 11th year, with extreme conditions in the most populated areas. Argentina reported its driest year since 1995. In North America, drought continued to prevail in the West. The lack of moisture in drought-stricken regions often provide ideal conditions for fire. Total fire emissions in the western United States in 2020 were almost three times higher than the 2003–10 mean. The Arctic experienced its highest fire year in terms of carbon emitted into the atmosphere, surpassing the record set in 2019 by 34%, with most of the fires occurring in Arctic Asia. In the tropics, the Amazon saw its highest fire activity since 2012, while fire activity in tropical Asia—including Indonesia—was one of the lowest on record, related to wet conditions as La Niña evolved during the fire season. The 2020 Southwest Asian Monsoon season (June–September) was the wettest since 1981, also coincident with the emergence of La Niña. The Meiyu rainy season, which usually occurs between July and August over the Yangtze and Huaihe River Valleys of China, was extended by two months in 2020. The May–October total rainfall averaged over the area was the most since the start of the record in 1961. Associated severe flooding affected about 45.5 million people. A widespread desert locust infestation during 2019–20 impacted equatorial and northern East Africa, as heavy rains and prevailing winds were favorable for breeding and movement of swarms across Kenya, Ethiopia, northeastern Somalia, Uganda, South Sudan, and northern Tanzania. The massive infestation destroyed thousands of square kilometers of cropland and pasture lands, resulting in one million people in need of food aid in Ethiopia alone. Extremely heavy rains in April also triggered widespread flooding and landslides in Ethiopia, Somalia, Rwanda, and Burundi. The Lake Victoria region was the wettest in its 40-year record. Across the global oceans, the average ocean heat content reached a record high in 2020 and the sea surface temperature was the third highest on record, surpassed only by 2016 and 2019. Approximately 84% of the ocean surface experienced at least one marine heatwave (MHW) in 2020. For the second time in the past decade, a major MHW developed in the northeast Pacific, covering an area roughly six times the size of Alaska in September. Global mean sea level was record high for the ninth consecutive year, reaching 91.3 mm above the 1993 average when satellite measurements began, an increase of 3.5 mm over 2019. Melting of the Greenland Ice Sheet accounted for about 0.8 mm of the sea level rise, with an overall loss of 293 ± 66 gigatons of ice. A total of 102 named tropical storms were observed during the Northern and Southern Hemisphere storm seasons, well above the 1981–2010 average of 85. In the North Atlantic, a record 30 tropical cyclones formed, surpassing the previous record of 28 in 2005. Major Hurricanes Eta and Iota made landfall along the eastern coast of Nicaragua in nearly the same location within a two-week period, impacting over seven million people across Central America. In the western North Pacific, Super Typhoon Goni was the strongest tropical cyclone to make landfall in the historical record and led to the evacuation of almost 1 million people in the Philippines. Very Severe Cyclonic Storm Gati was the strongest recorded cyclone to make landfall over Somalia. Bosaso, in northeast Somalia, received 128 mm of rainfall in a 24-hour period, exceeding the city’s average annual total of 100 mm. Above Earth’s surface, the annual lower troposphere temperature equaled 2016 as the highest on record, while stratospheric temperatures continued to decline. In 2020, the stratospheric winter polar vortices in both hemispheres were unusually strong and stable. Between December 2019 and March 2020, the Arctic polar vortex was the strongest since the beginning of the satellite era, contributing to record low stratospheric ozone levels in the region that lasted into spring. The anomalously strong and persistent Antarctic polar vortex was linked to the longest-lived, and 12th-largest, ozone hole over the region, which lasted to the end of December.

UR - http://www.scopus.com/inward/record.url?scp=85115757564&partnerID=8YFLogxK

U2 - 10.1175/2021BAMSStateoftheClimate.1

DO - 10.1175/2021BAMSStateoftheClimate.1

M3 - Review article

AN - SCOPUS:85115757564

SN - 0003-0007

VL - 102

SP - 1

EP - 481

JO - Bulletin of the American Meteorological Society

JF - Bulletin of the American Meteorological Society

IS - 8

ER -

Blunden J, Boyer T, Dunn RJH, Allen J, Andersen A, Hammer G et al. State of the climate in 2020. Bulletin of the American Meteorological Society. 2021 Aug;102(8):1-481. doi: 10.1175/2021BAMSStateoftheClimate.1