User:Kycn77/sandbox: Difference between revisions – Wikipedia

 

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</ref> 尽管如此，在这些年份中，北极海冰覆盖面积的总体平均水平似乎已从800万平方公里下降到500万平方公里。

</ref> 尽管如此，在这些年份中，北极海冰覆盖面积的总体平均水平似乎已从800万平方公里下降到500万平方公里。

===South Pole===

======

”另见”: ”[[:zh:南极洲气候|南极洲气候]]”

{{See also|Climate of Antarctica}}

[[File:Antarctica 6400px from Blue Marble.jpg|thumb|A satellite composite image of Antarctica]]

[[File:Antarctica 6400px from Blue Marble.jpg|thumb|]]

地球的[[:zh:南极洲|南极洲]]被南极冰盖覆盖。南极冰盖面积约1460万平方公里，冰储量在2500万至3000万立方公里之间。地球上约70%的[[:zh:淡水|淡水]]蕴藏在这片冰盖中。

Earth’s [[South Pole|south polar]] land mass, [[Antarctica]], is covered by the [[Antarctic ice sheet]]. It covers an area of about 14.6&nbsp;million km² and contains between 25 and 30&nbsp;million km³ of ice. Around 70% of the [[fresh water]] on Earth is contained in this ice sheet.

美国国家冰雪数据中心的数据显示，过去三十年（1979-2009年）南极洲的海冰覆盖稍微有增加。<ref>{{cite web

Data from the National Snow and Ice Data Center shows that the sea ice coverage of Antarctica has a slightly positive trend over the last three decades (1979–2009).<ref>{{cite web

|url=http://nsidc.org/sotc/sea_ice.html

|url=http://nsidc.org/sotc/sea_ice.html

|title=State of the Cryosphere / Arctic and Antarctic Standardized Anomalies and Trends Jan 1979 – Jul 2009

|title=State of the Cryosphere / Arctic and Antarctic Standardized Anomalies and Trends Jan 1979 – Jul 2009

极地冰盖 或者 冰帽 是行星、矮行星或天然卫星上被冰盖的高-纬度 纬度区域。^[1]

对于冰体被称为极地冰盖，没有任何关于大小或成分的要求，也没有任何关于它必须位于陆地上的地质要求，而只是要求它必须是极地中的固相物质体。这使得“极地冰盖”这个术语成为一个误称，因为冰帽一词本身的应用范围更狭隘，指的是陆地上的冰体，面积小于 50,000 平方公里；更大的冰体被称为冰盖

冰的成分各不相同。例如，地球的极地冰盖主要由水冰组成，而火星的极地冰盖则由固体二氧化碳和水冰混合而成。

极地冰盖的形成是因为高纬度地区接收到的太阳辐射能量比赤道地区少，导致地表温度较低。

过去12,000年来，地球的极地冰盖发生了巨大的变化。由于行星或月球绕太阳旋转时对太阳能的吸收量不同，冰盖会发生季节性变化。此外，在地质时间尺度上，冰盖可能会因气候变化而增大或缩小。

主条目: 極地

• 

  1978 – 2002年9月北极海冰范围

• 

  1978 – 2002年2月北极海冰范围

• 
  藍色彈珠, 从阿波罗17号看到的地球，可见南极冰盖（由NASA提供)

更多信息：北极冰海消融

地球的北极被北冰洋上空的浮冰（海冰）覆盖。部分非季节性融化的冰块会变得非常厚，大面积厚度可达3至4米，脊线厚度可达20米。一年冰厚通常约为1米。海冰覆盖面积在900万至1200万平方公里之间。另外，格陵蘭冰原覆盖面积约为171万平方公里，冰量约为260万立方公里。冰块断裂（崩裂）时，会形成散布在北大西洋周围的冰山。^[2]

根据美国国家冰雪数据中心的数据，“自1979年以来，冬季北极海冰面积每十年减少约4.2%”。2008年和2009年的北极海冰最小面积略高于2007年。根据美国国家冰雪数据中心的数据，一年中其他时间的海冰面积有时仍接近1979-2000年的平均水平，例如2010年4月。^[3] 尽管如此，在这些年份中，北极海冰覆盖面积的总体平均水平似乎已从800万平方公里下降到500万平方公里。

另见: 南极洲气候

地球的南极洲被南极冰盖覆盖。南极冰盖面积约1460万平方公里，冰储量在2500万至3000万立方公里之间。地球上约70%的淡水蕴藏在这片冰盖中。

美国国家冰雪数据中心的数据显示，过去三十年（1979-2009年）南极洲的海冰覆盖稍微有增加。^[4]

Over the past several decades, Earth’s polar ice caps have gained significant attention because of the alarming decrease in land and sea ice. NASA reports that since the late 1970s, the Arctic has lost an average of 20,800 square miles (53,900 square kilometres) of sea ice per year while the Antarctic has gained an average of 7,300 square miles (18,900 km²) of sea ice per year. At the same time, the Arctic has been losing around 50 cubic kilometres (gigatons) of land ice per year, almost entirely from Greenland’s 2.6 million gigaton sheet. On 19 September 2014, for the first time since 1979, Antarctic sea ice extent exceeded 7.72 million square miles (20 million square kilometres), according to the National Snow and Ice Data Center (NSIDC). The ice extent stayed above this benchmark extent for several days. The average maximum extent between 1981 and 2010 was 7.23 million square miles (18.72 million square kilometres). The single-day maximum extent in 2014 was reached on 20 Sep, according to NSIDC data, when the sea ice covered 7.78 million square miles (20.14 million square kilometres). The 2014 five-day average maximum was reached on 22 Sep, when sea ice covered 7.76 million square miles (20.11 million square kilometres), according to NSIDC.^[5] This increase could be due to the reduction in the salinity of the Antarctic Ocean as a result of the previous melting of the ice sheet, by increasing the freezing point of the seawater.

The current rate of decline of the ice caps has caused many investigations and discoveries on glacier dynamics and their influence on the world’s climate. In the early 1950s, scientists and engineers from the US Army began drilling into polar ice caps for geological insight. These studies resulted in “nearly forty years of research experience and achievements in deep polar ice core drillings… and established the fundamental drilling technology for retrieving deep ice cores for climatologic archives.”^[6] Polar ice caps have been used to track current climate patterns but also patterns over the past several thousands years from the traces of CO₂ and CH₄ found trapped in the ice. In the past decade, polar ice caps have shown their most rapid decline in size with no true sign of recovery.^[7] Josefino Comiso, a senior research scientist at NASA, found that the “rate of warming in the Arctic over the last 20 years is eight times the rate of warming over the last 100 years.”^[8] In September 2012, sea ice reached its smallest size ever. Journalist John Vidal stated that sea ice is “700,000 sq km below the previous minimum of 4.17m sq km set in 2007”.^[9] In August 2013, Arctic sea ice extent averaged 6.09m km², which represents 1.13 million km² below the 1981–2010 average for that month.^[10]

In addition to Earth, the planet Mars also has polar ice caps. They consist of primarily water-ice with a few percent dust.^[11] Frozen carbon dioxide makes up a small permanent portion of the Planum Australe or the South Polar Layered Deposits. In both hemispheres a seasonal carbon dioxide frost deposits in the winter and sublimates during the spring.^{[citation needed]}

Data collected in 2001 from NASA missions to Mars show that the southern residual ice cap undergoes sublimation inter-annually. The most widely accepted explanation is that fluctuations in the planet’s orbit are causing the changes.^[12]

On 29 April 2015, NASA stated that its New Horizons missions had discovered a feature thought to be a polar ice cap on the dwarf planet Pluto.^[13] The probe’s flyby of Pluto in July 2015 allowed the Alice ultraviolet imaging spectrometer to confirm that the feature was in fact an ice cap composed of methane and nitrogen ices.^[14]