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Climate Change,the Measure of Global Warming, May 11st, 2013, Economist
氣候變化，對全球變暖的測量，經(jīng)濟(jì)學(xué)人，2013年5月11日
AT NOON on May 4th the carbon dioxide concentration in the atmosphere around the Mauna Loa Observatory in Hawaii hit 400 parts per million (ppm).
5月4日中午，夏威夷莫納羅亞觀測站測量到在其附近大氣層中，二氧化碳的濃度達(dá)到了400ppm。
The average for the day was 399.73 and researchers at the observatory expect this figure，too, to exceed 400 in the next few days.
這天的平均濃度為399.73ppm。觀測站研究人員預(yù)計，在接下來的幾天，該數(shù)值將會超過400ppm。
The last time such values prevailed on Earth was in the Pliocene epoch，4m years ago, when jungles covered northern Canada.
距離上一次地球上出現(xiàn)這樣的濃度，是在4百萬年以前的上新世時期，那時候，加拿大北部地區(qū)被大片叢林所覆蓋。
Mauna Loa is the benchmark for CO2 measurement (and has been since 1958, see chart) because Hawaii is so far from large concentrations of humanity.
莫納羅亞地區(qū)是二氧化碳測量基準(zhǔn)（從1958年以來就是如此，如圖所示）。這是因為夏威夷遠(yuǎn)離人類大規(guī)模的聚齊地。
The Arctic,by contrast,gets a lot of polluted air from Europe and North America.
相比之下，北極有大量來自歐洲與北美洲的污染空氣。
This year the average reading for the whole month will probably also reach 400ppm，according to Pieter Tans，who is in charge of monitoring at Mauna Loa，and the seasonally adjusted annual figure will reach 400ppm in the spring of 2014 or 2015.
據(jù)在莫納羅亞負(fù)責(zé)監(jiān)控的Pieter Tans稱，今年5月的平均濃度可能也會達(dá)到400ppm，而在2014年或2015年的春季，數(shù)值將會達(dá)到400ppm。
Mauna Loa's readings are one of the world's longest-running measurement series.
莫納羅亞測量的測量值是世界上使用時間最長的測量標(biāo)準(zhǔn)之一。
The first，made in March 1958，was 315ppm. That means they have risen by a quarter in 55 years.
第一次的測量值是在1958年3月，為315ppm。這意味著，在55年內(nèi)，二氧化碳濃度增加了四分之一。
In the early 1960s they were going up by 0.7ppm a year.
在20世紀(jì)60年代早期，二氧化碳濃度以每年0.7ppm的速度增長。
The rate of increase is now 2.1 ppm—three times as fast—reflecting the relentless rise in greenhouse-gas emissions.
現(xiàn)在的增長速度為2.1ppm，相當(dāng)于那時的三倍，這說明溫室氣體的排放一直都有增無減。
As a rule of thumb，CO2 concentrations will have to be restricted to about 450ppm if global warming is to be kept below 20℃(a level that might possibly be safe).
一般來說，如果全球溫度上升保持在20攝氏度以下（可能安全的標(biāo)準(zhǔn)），二氧化碳的濃度必須限制在450ppm左右。
Because CO2 stays in the atmosphere for decades, artificial emissions of the gas would have to be cut immediately，and then fall to zero by 2075，in order to achieve 450ppm.
因為二氧化碳可以在大氣層中存在幾十年，所以要想達(dá)到450ppm，必須立刻減少對這種氣體的人工排放，然后在2075年達(dá)到零排放。
There seems no chance of that. Emissions are still going up. At current rates，the Mauna Loa reading will rise above 450ppm in 2037.Thank you.
照目前形勢看，這似乎是不可能的。廢氣依然有增無減。以目前的速度，2037年莫納羅亞測量的二氧化碳濃度將會超過450ppm。謝謝。
