State of the climate in 2018

• Published in: Bulletin of the American Meteorological Society
• Main Authors: Ades, M., Adler, R., Aldeco, Laura S., Alejandra, G., Alfaro, Eric J., Aliaga-Nestares, Vannia, Allan, Richard P., Allan, Rob, Alves, Lincoln M., Amador, Jorge A., Andersen, J. K., Anderson, John, Arndt, Derek S., Arosio, C., Arrigo, Kevin, Azorin-Molina, César, Bardin, M. Yu, Barichivich, Jonathan, Barreira, Sandra, Baxter, Stephen, Beck, H. E., Becker, Andreas, Bell, Gerald D., Bellouin, Nicolas, Belmont, M., Benedetti, Angela, Benedict, Imme, Bernhard, G. H., Berrisford, Paul, Berry, David I., Bettio, Lynette, Fogt, Ryan L.
• Format: Text
• Language: unknown
• Published: OHIO Open Library 2019
• Subjects: Geography; Arctic; Greenland; Ice; ice core; permafrost
• Online Access: https://ohioopen.library.ohio.edu/geography-oapub/1; https://doi.org/10.1175/2019BAMSStateoftheClimate.1

© 2019 American Meteorological Society. All rights reserved. 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 ...