章节大纲

  • 常规

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  • 全球变暖

    Comparison of Grinnell Glacier in 1940 and 2006, showing significant melting over time.
     

    How can things change so quickly?
    ::事情怎么这么快就变了?

     and ice sheets are melting. This can be seen clearly in photographs. The glaciers advanced during the Pleistocene  ice age . They have been melting back since then, except for during the Little Ice Age. However, the rate of melting has increased tremendously in recent decades.
    ::冰盖正在融化。 这在照片中可以清楚地看到。 冰川在冰河时代不断进步。 冰川从那时起就一直在融化, 但小冰时代除外。 然而, 融化的速度近几十年来急剧上升。

    Temperature Variations
    ::温度变化变化

    Since the end of the Pleistocene, Earth’s   has risen. The image below shows how it changed over just the last 1500 years ( Figure   ). The Medieval Warm Period was a time of somewhat higher average temperatures. The Little Ice Age was a time of somewhat lower average temperatures. But for each time, the anomaly (the difference from average temperature) was less than 1° C (1.8° F). Still, the overall trend is slightly upward.
    ::自Pleistocene结束以来,地球已经上升了。下面的图像显示了它在过去1500年中的变化(图 ) 。 中世纪温期是平均气温略高的时期。 小冰期是平均气温略低的时期。 但每次异常(与平均温度的差异)都低于1°C(与平均温度的差异 ) ( 1.8°F ) 。 尽管如此,总体趋势还是略有上升。

    Graph showing temperature anomalies over 1500 years, highlighting Medieval Warm Period and Little Ice Age.
     
    Earth’s temperature. Different sets of data all show an increase in temperature since about 1880 (the Industrial Revolution).

    Recent Temperature Trends
    ::最近温度趋势

    Since the mid 1800s, Earth has warmed up quickly ( Figure   ). By the end of 2017, 17 of the 18 hottest years on record have all occurred since 1998! This temperature rise is what is usually meant by  global warming .
    ::自1800年代中期以来,地球迅速变暖(图 ) 。 到2017年底,18个最热的年份中,有记录显示的17个年份都发生在1998年。 气温上升通常是指全球变暖。

    Graph showing Earth's temperature trends from 1850 to 2007 with annual and 5-year averages.
     
    Earth’s temperature (1850–2007). Earth has really heated up over the last 150 years. Do you know why?

    Summary
    ::摘要

    • Average global temperature has been rising since the end of the ice ages.
      ::自冰河时代结束以来,全球平均气温一直在上升。
    • The largest temperature rise has been in the past two decades.
      ::过去二十年来,气温上升幅度最大。
    • The rise in Earth's temperature since the late 19th century is referred to as global warming.
      ::自19世纪末以来地球温度的上升被称为全球变暖。

    Review
    ::回顾

    1. What have been the temperature trends in the past 1500 years?
      ::过去1500年的温度趋势是什么?
    1. How is the rise in temperatures in the past two decades different from the rise of the past 1500 years?
      ::过去20年的气温上升与过去1500年的上升有何不同?
    1. What is global warming?
      ::什么是全球变暖?