Abstract
In 2018, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued their increase. The annual global average carbon dioxide concentration at Earth's surface was 407.4 ± 0.1 ppm, the highest in the modern instrumental record and in ice core records dating back 800 000 years. Combined, greenhouse gases and several halogenated gases contribute just over 3 W m−2 to radiative forcing and represent a nearly 43% increase since 1990. Carbon dioxide is responsible for about 65% of this radiative forcing. With a weak La Niña in early 2018 transitioning to a weak El Niño by the year's end, the global surface (land and ocean) temperature was the fourth highest on record, with only 2015 through 2017 being warmer. Several European countries reported record high annual temperatures. There were also more high, and fewer low, temperature extremes than in nearly all of the 68-year extremes record. Madagascar recorded a record daily temperature of 40.5°C in Morondava in March, while South Korea set its record high of 41.0°C in August in Hongcheon. Nawabshah, Pakistan, recorded its highest temperature of 50.2°C, which may be a new daily world record for April. Globally, the annual lower troposphere temperature was third to seventh highest, depending on the dataset analyzed. The lower stratospheric temperature was approximately fifth lowest. The 2018 Arctic land surface temperature was 1.2°C above the 1981-2010 average, tying for third highest in the 118-year record, following 2016 and 2017. June's Arctic snow cover extent was almost half of what it was 35 years ago. Across Greenland, however, regional summer temperatures were generally below or near average. Additionally, a satellite survey of 47 glaciers in Greenland indicated a net increase in area for the first time since records began in 1999. Increasing permafrost temperatures were reported at most observation sites in the Arctic, with the overall increase of 0.1°-0.2°C between 2017 and 2018 being comparable to the highest rate of warming ever observed in the region. On 17 March, Arctic sea ice extent marked the second smallest annual maximum in the 38-year record, larger than only 2017. The minimum extent in 2018 was reached on 19 September and again on 23 September, tying 2008 and 2010 for the sixth lowest extent on record. The 23 September date tied 1997 as the latest sea ice minimum date on record. First-year ice now dominates the ice cover, comprising 77% of the March 2018 ice pack compared to 55% during the 1980s. Because thinner, younger ice is more vulnerable to melting out in summer, this shift in sea ice age has contributed to the decreasing trend in minimum ice extent. Regionally, Bering Sea ice extent was at record lows for almost the entire 2017/18 ice season. For the Antarctic continent as a whole, 2018 was warmer than average. On the highest points of the Antarctic Plateau, the automatic weather station Relay (74°S) broke or tied six monthly temperature records throughout the year, with August breaking its record by nearly 8°C. However, cool conditions in the western Bellingshausen Sea and Amundsen Sea sector contributed to a low melt season overall for 2017/18. High SSTs contributed to low summer sea ice extent in the Ross and Weddell Seas in 2018, underpinning the second lowest Antarctic summer minimum sea ice extent on record. Despite conducive conditions for its formation, the ozone hole at its maximum extent in September was near the 2000-18 mean, likely due to an ongoing slow decline in stratospheric chlorine monoxide concentration. Across the oceans, globally averaged SST decreased slightly since the record El Niño year of 2016 but was still far above the climatological mean. On average, SST is increasing at a rate of 0.10° ± 0.01°C decade−1 since 1950. The warming appeared largest in the tropical Indian Ocean and smallest in the North Pacific. The deeper ocean continues to warm year after year. For the seventh consecutive year, global annual mean sea level became the highest in the 26-year record, rising to 81 mm above the 1993 average. As anticipated in a warming climate, the hydrological cycle over the ocean is accelerating: dry regions are becoming drier and wet regions rainier. Closer to the equator, 95 named tropical storms were observed during 2018, well above the 1981-2010 average of 82. Eleven tropical cyclones reached Saffir-Simpson scale Category 5 intensity. North Atlantic Major Hurricane Michael's landfall intensity of 140 kt was the fourth strongest for any continental U.S. hurricane landfall in the 168-year record. Michael caused more than 30 fatalities and $25 billion (U.S. dollars) in damages. In the western North Pacific, Super Typhoon Mangkhut led to 160 fatalities and $6 billion (U.S. dollars) in damages across the Philippines, Hong Kong, Macau, mainland China, Guam, and the Northern Mariana Islands. Tropical Storm Son-Tinh was responsible for 170 fatalities in Vietnam and Laos. Nearly all the islands of Micronesia experienced at least moderate impacts from various tropical cyclones. Across land, many areas around the globe received copious precipitation, notable at different time scales. Rodrigues and Réunion Island near southern Africa each reported their third wettest year on record. In Hawaii, 1262 mm precipitation at Waipā Gardens (Kauai) on 14-15 April set a new U.S. record for 24-h precipitation. In Brazil, the city of Belo Horizonte received nearly 75 mm of rain in just 20 minutes, nearly half its monthly average. Globally, fire activity during 2018 was the lowest since the start of the record in 1997, with a combined burned area of about 500 million hectares. This reinforced the long-term downward trend in fire emissions driven by changes in land use in frequently burning savannas. However, wildfires burned 3.5 million hectares across the United States, well above the 2000-10 average of 2.7 million hectares. Combined, U.S. wildfire damages for the 2017 and 2018 wildfire seasons exceeded $40 billion (U.S. dollars).
| Original language | English (US) |
|---|---|
| Pages (from-to) | SI-S305 |
| Journal | Bulletin of the American Meteorological Society |
| Volume | 100 |
| Issue number | 9 |
| DOIs | |
| State | Published - Jan 1 2019 |
Bibliographical note
Funding Information:• The Swiss Network PERMOS is financially sup-ported by MeteoSwiss in the framework of GCOS Switzerland, the Federal Office for the Environ-ment, and the Swiss Academy of Sciences and acknowledges the important contribution of the partner institutions and principal investigators. The French Network PermaFRANCE is financially supported by OSUG (Observatoire des Sciences de l’Univers Grenoble) and the French Research Infrastructure OZCAR.
Funding Information:
• The GFASv1.4 dataset was provided the by GFAS-CLIM project, funded by the German Bundesmin-isterium für Wirtschaft und Energie (BMWi/DLR FKZ 50EE1543), and the Copernicus Atmosphere Monitoring Service (CAMS_44).
Funding Information:
• Work performed by Stephen Po-Chedley at LLNL was performed under the auspices of the U.S. Department of Energy under Contract DE-AC52-07NA27344 and LDRD 18-ERD-054.
Funding Information:
• This research has been supported by the NASA CERES project. The NASA Langley Atmospheric Sciences Data Center processed the instantaneous Single Scanner Footprint (SSF) data used as input to EBAF Ed4.0 and processes the FLASHFlux TISA v3C.
Funding Information:
• S. Hagos is supported by NOAA's Oceanic and Atmospheric Research, Climate Program Office, under NOAA Grant No. NA17OAR4310263 and Z. Feng is supported by U.S. Department of Energy Office of Science Biological and Environmental Research as part of the Atmospheric Systems Research Program. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RLO1830. • We acknowledge the meteorological and hydro-logical services of: Morocco, Algeria, Nigeria, The Gambia, South Africa and the southern Indian Ocean Island countries of Madagascar, Seychelles, Mayotte (France), La Réunion (France), Mauritius, and Rodrigues (Mauritius).
Funding Information:
• David Bromwich and Sheng-Hung Wang were supported by NSF grant PLR 1823135.
Funding Information:
• Ted Scambos was supported under NASA grant NNX16AN60G and NSF PLR 1565576, and thanks the National Snow and Ice Data Center. Sharon Stammerjohn was supported under NSF PLR 1440435; she also thanks the Institute of Arctic and Alpine Research and the National Snow and Ice Data Center, both at the University of Colorado Boulder, for institutional and data support.
Funding Information:
• The chapter editors thank Paul Berrisford and Ju-lien Nicholas (ECMWF), Mike Bosilovich (NASA), and Shinya Kobayashi (JMA) for timely provision of reanalysis data used herein. We thank Philip Brohan, Mark McCarthy, David Parker, Roger Saunders, and Christoforos Tsamalis for their reviews and thoughts on this chapter. • Robert Dunn, Colin Morice, and Kate Willett were supported by the Joint UK BEIS/Defra Met Office Hadley Centre Climate Programme (GA01101).
Funding Information:
• G. Bernhard and coauthors acknowledge the support of Biospherical Instruments, San Diego; the Research Council of Norway through its Centers of Excellence funding scheme, project number 223268/F50; and the Academy of Finland for supporting UV measurements through the FARPOCC, SAARA, and DACES projects. We also thank the Microwave Limb Sounder team at NASA’s Jet Propulsion Laboratory for data processing and analysis support; Tove Svendby from the Norwegian Institute for Air Research and Arne Dahlback from the University of Oslo for overseeing UV measurements at Oslo, Andøya, and Ny-Ålesund; and Juha M. Karhu, Tomi Karp-pinen, and Markku Ahponen from the Finnish Meteorological Institute for operating the Brewer UV spectroradiometer at Sodankylä.
Funding Information:
• The CAMS reanalysis has been produced by the Copernicus Atmosphere Monitoring Services (CAMS), which is a program funded by the Euro-pean Union. The European Centre for Medium-Range Weather Forecast (ECMWF) operates CAMS on behalf of the European Commission. Melanie Ades, Olivier Boucher, Zak Kipling, and Samuel Rémy are funded by CAMS. • Melanie Coldewey-Egbers, Daan Hubert, Diego Loyola, Victoria Sofieva, and Mark Weber are grateful to ESA’s Climate Change Initiative Ozone project and to the EU Copernicus Climate Change Service 312a Lot4 Ozone project for supporting the generation and extension of the GTO-ECV total ozone and SAGE-CCI-OMPS data records. Stacey M. Frith is supported by the NASA Long-Term Measurement of Ozone program WBS 479717. Lucien Froidevaux’s contribution, with the assistance of Ryan Fuller, was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Daan Hubert acknowledges the partial support by the EU/ERC Horizon 2020 project GAIA-CLIM. • Dale Hurst would like to thank NASA’s Upper Atmosphere Composition Observations program and NOAA’s Climate Program Office for fund-ing that helps sustain the frost point hygrometer soundings at Boulder, Lauder, and Hilo. • We are grateful to Emillio Cuevas (AEMET) for providing monthly mean flask observations from Izana station for 2018.
Funding Information:
• Debbie Hemming was supported by the Met Of-fice Hadley Centre Climate Programme funded by BEIS and Defra, and thanks all co-authors for their interesting and helpful contributions, and Robert Dunn for his expertise finalizing the figures for this section. The work for MODIS land surface phenology was funded by NASA Earth Science Di-rectorate (grants NNX16AO34H, NNX14AP80A, and NNX14AI71G). Support for the development and maintenance of PhenoCam network infra-structure has come from the National Science Foundation, through the Macrosystems Biology program, awards EF-1065029 and EF-1702697. Nature’s Calendar thanks all of its volunteer recorders without whom it could not function. Stephen Thackeray thanks Heidrun Feuchtmayr for managing the Windermere database, and Mitzi De Ville, Ben James, Ellie Mackay, Mike Clarke, and Bev Dodd for collecting the data (current field team).
Funding Information:
• The work of Rob Massom, Phil Reid, Jan Lieser, and Steve Rintoul was supported by the Australian Government’s Cooperative Research Centre pro-gram through the Antarctic Climate & Ecosystems CRC, and contributes to AAS Project 4116. PR was also supported through the Bureau of Meteorol-ogy. JLL was supported under Australian Research Council’s Special Research Initiative for Antarctic Gateway Partnership (Project ID SR140300001).
Funding Information:
• Hyungjun Kim was supported by the Japan So-ciety for the Promotion of Science KAKENHI (16H06291 and 18KK0117) for this contribution.
Funding Information:
• Christopher Shuman was supported by NASA’s Cryospheric Sciences Program and thanks the University of Maryland, Baltimore County’s Joint Center for Earth System Technology and the Cryo-spheric Sciences Laboratory at NASA Goddard Space Flight Center.
Funding Information:
• Andrew Meijers was supported by the Natural Environment Research Council via award NE/ J008494/1. Jean-Baptiste Sallée was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and in-novation program (Grant Agreement no 637770). Sebastiaan Swart was supported by a Wallenberg Academy Fellowship, (WAF 2015.0186). Mike Mer-edith received funding from the Natural Environ-ment Research Council via award NE/N018095/1. SOCCOM is supported by the National Science Foundation under NSF Award PLR-1425989. OR-CHESTRA is funded by the Natural Environment Research Council, and is a joint program of the British Antarctic Survey, National Oceanography Centre, Plymouth Marine Laboratory, British Geological Survey, Sea Mammal Research Unit, Centre for Polar Observation and Modelling, and the UK Met Office. The authors thank the teams of scientists from these centres that are contributing to the programs.
Funding Information:
• Kyle Clem would like to thank the Rutgers Insti-tute of Earth, Ocean, and Atmospheric Sciences for postdoctoral support. Linda Keller and Mat-thew’s contribution is based upon work supported by the National Science Foundation under Grant No. 1543305.
Funding Information:
• The ESA CCI SM datasets and the authors were supported by ESA’s Climate Change Initiative for Soil Moisture (Contract No. 4000104814/11/I-NB and 4000112226/14/I-NB). We would also like to thank support from the Copernicus Climate Change Service implemented by ECMWF.
Funding Information:
• This research was supported by NASA’s Terrestrial Hydrology Program and GRACE and GRACE Follow-On Science Team.
Funding Information:
• The editors would like to extend their thanks and appreciation to Andrew Magee from the Univer-sity of Newcastle; Newcastle, NSW, Australia for his inputs. Carl Schreck was supported by NOAA through the Cooperative Institute for Climate and Satellites – North Carolina under Cooperative Agreement NA14NES432003.
Funding Information:
• Kate Willett was supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra.
Funding Information:
• Robert Dunn was supported by the Met Office Hadley Centre Climate Programme funded by BEIS and Defra.
Funding Information:
• This work is funded in part by NOAA’s Climate Data Record (CDR) Program located in Asheville, NC at the National Centers for Environmental Information.
Funding Information:
• Matthew Druckenmuller was supported by the Study of Environmental Arctic Change (SEARCH, NSF grant PLR-1331100).
Funding Information:
• Jonathan Barichivich received funding from Chile FONDECYT grant No. 1181956. Tim Osborn re-ceived funding from UK NERC (NE/P006809/1). Ian Harris received funding from UK National Centre for Atmospheric Science (NCAS).
Funding Information:
• Vladimir Romanovsky and co-authors of the Permafrost essay acknowledge the support of the State of Alaska, the National Science Foundation (grants PLR-0856864 and PLR-1304271 to the University of Alaska Fairbanks; PLR-1002119 and PLR-1304555 to the George Washington University), and by Natural Resources Canada. Support was also provided by the Russian Science Foundation (project RNF 16-17-00102) and by the government of the Russian Federation.
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ASJC Scopus subject areas
- Atmospheric Science
