When scientists scan the global horizon, over-fishing, loss of species habitat, water shortage, climate change, and invasive species look to be the biggest threats to the earth.

    研究者們環視全球，發現過度捕撈、物種棲息地缺失、水資源缺乏、氣候變化和外來物種入侵是對地球最大的威脅。

    What will our world be like in 2050?

    到2050年的時候，我們的世界會是什么樣子？
 
    Population Decrease and Increase 人口增減

    There are two features in the growth of world population. First, the annual increase in population in 15 European countries, in the past few years, has been only 300,000. The United Nations estimates that by 2050, the population of European countries will decrease from the current 0.72 billion to 0.63 billion. Second, the population in developing countries is growing rapidly. Over the past 50 years, the rate of increase in population has been fastest in the least developed countries. By 2050, the population of Africa is expected to reach 1.8 billion, 0.9 billion more than its current population.

    世界人口增長有兩個特點。首先，在過去的幾年中，歐洲15個國家每年僅增加人口30萬。聯合國預測，到2050年，歐洲人口將由目前的7.2億下降到 6.3億。其次，發展中國家人口正快速增長。在過去50年里，最不發達國家的人口增長率最高。到2050年，非洲總人口將達到18億，比目前多9億。
 
    Global Warming 全球變暖

    A recent research report published by the United Nations indicates that it is quite possible that the Earth's temperature is rising well above the previous estimate.

    最近由聯合國公布的研究報告指出，地球溫度的上升很可能遠高于以前的估計。

    Such an outcome would have severe consequences, such as the collapse of the Greenland ice sheet and disruption of the Gulf Stream ocean current.

    這樣的結果會造成嚴重后果，例如格陵蘭冰層崩塌以及墨西哥灣流受阻。

    The Antarctic ice sheet, which contains 90% of the world's ice, has lost significant mass in the past few years. The discovery comes as a surprise to scientists, who thought that the continent would gain ice this century because of increased snowfall in a warming climate.

    占有全世界冰川總量90%的南極洲冰層主體在過去幾年里顯著萎縮。對于科學家們來說，這個發現出乎意料，因為他們曾經認為溫暖的氣候會帶來更多降雪，從而在本世紀增加南極洲的總冰量。

    A research team from the University of Colorado used satellite data to estimate that the ice sheet will lose up to 48 cubic miles by 2050. In comparison, a city the size of Los Angeles uses one cubic mile of fresh water every year. Ice shelves in the Antarctic will have decreased by more than 7,200 square miles in the next four decades.

    科羅拉多州大學的研究小組利用衛星資料進行預測，到2050年（南極洲）冰層將會喪失多達48立方英里的冰量。與之相對的是，洛杉磯這樣規模的大城市一年消耗的淡水總量也不過1立方英里。在未來40年里，南極洲冰架將縮減7200多平方英里。

    At twice the size of Australia, Antarctica is the Earth's fifth largest continent and contains 70% of its total fresh water resources.

    南極洲是地球第五大洲，面積是澳大利亞的兩倍，擁有全球淡水資源的70%。
 
    Water Shortage 水資源短缺

    Africa's rivers face dramatic change that will leave a quarter of the continent severely short of water by the middle of the century, according to a global warming study published today.

    在今天出版的全球變暖問題研究報告稱，非洲河流正面臨巨變，這將導致在本世紀中葉，非洲四分之一的地區處于嚴重缺水狀態。

    Even modest decreases in rain in western Africa will see rivers lose as much as 80% of their water, triggering a surge of what the scientists call "water refugees".

    即便是在西非出現降雨的適度減少，也會造成河流損失多達80%的水量，引發專家們稱之為“水難民”的難民潮。

    "In those areas where there is already a water shortage, it's going to have a devastating affect," the study says. "If you're already walking 5 km to the nearest stream to get water, by 2050, it's going to mean walking 30 km or moving your whole household closer to the water source."

    該報告指出：“在那些水資源本來就很缺乏的地區，事情的發展將會帶來災難性的影響。如果現在需要徒步到5公里以外最近的水源地取水，到2050年就意味著要到30公里之外，或者只能搬到離水源更近的地方。”
 
    Four Wheels Good, Four Wheels Dad 成也汽車，敗也汽車

    The car has transformed the lives of people, but the planet is paying too high a price. It is almost incredible to think that when our grandparents were born cars were a rarity. Today there are 620 million private cars worldwide, to say nothing of buses, vans and lorries. With current growth trends, that number is expected to reach a staggering three billion cars worldwide by 2050.

    小汽車改變了我們的生活，然而這個世界現在正為此付出高昂的代價。幾乎讓人難以想象的是，在我們祖輩出生的年代，汽車還為罕見之物。如今，全球光私人小汽車就有6億2千萬輛，更不用說公共汽車、貨車和卡車了。按照眼下的增長態勢來看，到了2050年，這個數字將達到驚人的30億輛。

    If we continue to burn fossil fuels at current rates, levels of carbon dioxide in the atmosphere will reach 550 ppm (parts per million)--double pre-industrial levels--by around 2050. This will increase global temperatures between 1.4 and 4.8℃ by 2050, and sea levels will rise between 0.09 and 0.78 meters.

    如果我們繼續按照目前的標準使用礦物燃料，到2050年全球大氣中的二氧化碳含量將達到550ppm（百萬分率）。這個數字是人類進入工業化社會前的兩倍。受此影響，到2050年為止，全球溫度將增長1.4到4.8攝氏度，海平面將升高0.09到0.78米。