| Titre | Permafrost thermal state |
| Auteur | Christiansen, H H; Noetzli, V; Romanovsky, V; Shiklomanov, N; Smith, S; Vieira, G; Zhao, L |
| Source | State of the Climate in 2012; par Blunden, J (éd.); Arndt, D S (éd.); Bulletin of the American Meteorological Society vol. 94, no. 8 supplement, 2013 p. S15-S16, https://doi.org/10.1175/2013BAMSStateoftheClimate.1 (Accès ouvert) |
| Année | 2013 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20130438 |
| Éditeur | American Meteorological Society |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1175/2013BAMSStateoftheClimate.1 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Lat/Long OENS | -180.0000 180.0000 84.0000 60.0000 |
| Lat/Long OENS | -70.0000 -55.0000 -60.0000 -70.0000 |
| Programme | Géosciences de changements climatiques, Surveillance des variables climatiques |
| Résumé | (disponible en anglais seulement)
For the first time in several years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Niña dissipated
to ENSOneutral conditions by spring, and while El Niño appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern equatorial Pacific uncharacteristically returned to neutral conditions.
Nevertheless, other large-scale climate patterns and extreme weather events impacted various regions during the year. A negative phase of the Arctic Oscillation from mid-January to early February contributed to frigid conditions in parts of northern
Africa, eastern Europe, and western Asia. A lack of rain during the 2012 wet season led to the worst drought in at least the past three decades for northeastern Brazil. Central North America also experienced one of its most severe droughts on record.
The Caribbean observed a very wet dry season and it was the Sahel's wettest rainy season in 50 years. Overall, the 2012 average temperature across global land and ocean surfaces ranked among the 10 warmest years on record. The global land surface
temperature alone was also among the 10 warmest on record. In the upper atmosphere, the average stratospheric temperature was record or near-record cold, depending on the dataset. After a 30-year warming trend from 1970 to 1999 for global sea surface
temperatures, the period 2000-12 had little further trend. This may be linked to the prevalence of La Niña-like conditions during the 21st century. Heat content in the upper 700 m of the ocean remained near record high levels in 2012. Net increases
from 2011 to 2012 were observed at 700-m to 2000-m depth and even in the abyssal ocean below. Following sharp decreases in global sea level in the first half of 2011 that were linked to the effects of La Niña, sea levels rebounded to reach records
highs in 2012. The increased hydrological cycle seen in recent years continued, with more evaporation in drier locations and more precipitation in rainy areas. In a pattern that has held since 2004, salty areas of the ocean surfaces and subsurfaces
were anomalously salty on average, while fresher areas were anomalously fresh. Global tropical cyclone activity during 2012 was near average, with a total of 84 storms compared with the 1981-2010 average of 89. Similar to 2010 and 2011, the North
Atlantic was the only hurricane basin that experienced above-normal activity. In this basin, Sandy brought devastation to Cuba and parts of the eastern North American seaboard. All other basins experienced either near- or below-normal tropical
cyclone activity. Only three tropical cyclones reached Category 5 intensity-all in the Western North Pacific basin. Of these, Super Typhoon Bopha became the only storm in the historical record to produce winds greater than 130 kt south of 7°N. It was
also the costliest storm to affect the Philippines and killed more than 1000 residents. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June both reached new record lows. June snow cover extent is now declining
at a faster rate (-17.6% per decade) than September sea ice extent (-13.0% per decade). Permafrost temperatures reached record high values in northernmost Alaska. A new melt extent record occurred on 11-12 July on the Greenland ice sheet; 97% of the
ice sheet showed some form of melt, four times greater than the average melt for this time of year. The climate in Antarctica was relatively stable overall. The largest maximum sea ice extent since records begain in 1978 was observed in September
2012. In the stratosphere, warm air led to the second smallest ozone hole in the past two decades. Even so, the springtime ozone layer above Antarctica likely will not return to its early 1980s state until about 2060. Following a slight decline
associated with the global financial crisis, global CO2 emissions from fossil fuel combustion and cement production reached a record 9.5 ± 0.5 Pg C in 2011 and a new record of 9.7 ± 0.5 Pg C is estimated for 2012. Atmospheric CO2 concentrations
increased by 2.1 ppm in 2012, to 392.6 ppm. In spring 2012, for the first time, the atmospheric CO2 concentration exceeded 400 ppm at 7 of the 13 Arctic observation sites. Globally, other greenhouse gases including methane and nitrous oxide also
continued to rise in concentration and the combined effect now represents a 32% increase in radiative forcing over a 1990 baseline. Concentrations of most ozone depleting substances continued to fall. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Not available |
| GEOSCAN ID | 293576 |
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