State of the Climate in 2012
State of the Climate in 2012
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DOI：
10.1175/2013bamsstateoftheclimate.1
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发表时间：
2013-08-01
影响因子：
8
通讯作者：
Zimmermann, S.
中科院分区：
文献类型：
--
作者：
Blunden, Jessica;Arndt, Derek S.;Zimmermann, S.
多年来，厄尔尼诺-南方涛动第一次没有主导地球仪周围的区域气候条件。一个微弱的拉尼娜现象在春季消散到ENSO中性条件，而厄尔尼诺现象似乎在夏季出现，这一阶段从未完全发展为东部条件下的海面温度。然而，其他大规模气候模式和极端天气事件在这一年中影响了各个区域。从1月中旬到2月初，北极涛动的负相位导致了北方非洲、东欧和西亚部分地区的寒冷天气。2012年雨季的干旱导致巴西东北部至少在过去三十年中最严重的干旱。北美中部也经历了有史以来最严重的干旱之一。加勒比经历了一个非常潮湿的旱季，这是萨赫勒地区50年来最潮湿的雨季，总体而言，2012年全球陆地和海洋表面的平均温度是有记录以来最热的10个年份之一。仅全球陆地表面温度也是有记录以来最热的10个国家之一。在高层大气中，平流层的平均温度是创纪录的或接近创纪录的寒冷，这取决于数据集。在1970年至1999年全球海洋表面温度出现30年的变暖趋势之后，2000年至2012年期间几乎没有进一步的趋势。这可能与世纪拉尼娜现象的流行有关。2012年，海洋上层700米的热含量仍接近创纪录的高水平。2011年至2012年，在700米至2 000米深度，甚至在下面的深海中，都观察到了净增加。受拉尼娜现象影响，海平面急剧下降，2012年海平面反弹至历史新高。近年来水文循环加剧的现象仍在继续，干旱地区蒸发量增加，多雨地区降水量增加。自2004年以来，海洋表面和次表面的咸区平均为高盐度，而淡水区则为高盐度。2012年的全球热带气旋活动接近平均水平，共有84场风暴，而1981年至2010年的平均水平为89场。与2010年和2011年类似，北大西洋是唯一一个活动超过正常水平的飓风盆地。在这个盆地，桑迪给古巴和北美东部沿海地区带来了破坏。所有其他盆地都经历了接近或低于正常的热带气旋活动。只有三个热带气旋达到5级强度--都在宝霞，成为历史记录中唯一一个在北纬7度以南产生风速超过130海里的风暴。这也是影响菲律宾的最昂贵的风暴，造成1000多名居民死亡。9月北极海冰的最小范围和6月北方积雪覆盖范围都达到了新的历史低点。6月积雪覆盖范围的下降速度（每十年-17.6%）比9月海冰覆盖范围（每十年-13.0%）更快。阿拉斯加最北部的永久冻土温度达到创纪录的高值。7月11日至12日，格陵兰冰盖出现了新的融化范围记录，97%的冰盖出现了某种形式的融化，比每年这个时候的平均融化量大四倍。南极洲的气候总体上相对稳定。2012年9月观测到自1978年有记录以来最大的海冰范围。在平流层，温暖的空气导致了过去二十年来第二小的臭氧空洞。尽管如此，南极洲上空的春季臭氧层可能要到2060年左右才能恢复到20世纪80年代初的状态。在全球2排放量略有下降之后，2011年化石燃料燃烧和水泥生产的排放量达到创纪录的9.5 +/- 0.5 Pg C，估计2012年将达到9.7 +/- 0.5 Pg C的新纪录。2012年，大气二氧化碳浓度增加了2.1 ppm，达到392.6 ppm。2012年春季，北极13个观测点中的7个观测点的2浓度超过400 ppm。在全球范围内，包括甲烷和一氧化二氮在内的其他温室气体的浓度也继续上升，综合效应现在表明辐射强迫比1990年基线增加了32%。大多数臭氧消耗物质的浓度继续下降。
For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern 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 Ni a-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 to the effects of La Ni a, 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 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 2 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, 2 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.