不同的數(shù)據(jù)，同樣的趨勢(shì)

英國(guó)氣象局觀測(cè)數(shù)據(jù)

每一年，來(lái)自全球幾大主要?dú)庀笱芯克绹?guó)國(guó)家航天航空局下屬的戈達(dá)德太空研究所（GISS），美國(guó)國(guó)家海洋和大氣管理局的國(guó)家氣象數(shù)據(jù)中心（NCDC），日本氣象廳和英國(guó)氣象局的哈德利氣象中心——的科學(xué)家們會(huì)統(tǒng)計(jì)世界各地氣象站的數(shù)據(jù)，獨(dú)立的得出這一年與之前相比是更溫暖了還是更寒冷。

On January 12, 2011, the NASA group announced that 2010 had tied 2005 as the warmest year in their 131-year instrumental record. NOAA also declared 2010 to be tied with 2005. The Japanese Meteorological Agency noted in a preliminary analysis that 2010 was the second warmest. The Met Office Hadley Centre has yet to make its announcement.

2011年1月12日，美國(guó)國(guó)家航天航空局（NASA）宣布2010年和2005年的一樣，是在他們有儀器記錄的131年里最溫暖的一年。美國(guó)國(guó)家海洋和大氣管理局（NOAA）也宣布2010和2005年溫度持平。日本氣象廳的初步分析結(jié)果是2010年是歷史上第二溫暖的年份。哈德利氣象中心還沒(méi)有得出結(jié)論。

But how much does the ranking of a single year matter? Not all that much, said James Hansen, the director of NASA GISS. In his group’s analysis, 2010 differed from 2005 by less than 0.01°C (0.018 °F), a difference so small that the temperatures of the two years are almost indistinguishable, given the uncertainty of the calculation. Meanwhile, the third warmest year, 2009, is so close to 1998, 2002, 2003, 2006, and 2007 (the maximum difference between years is 0.03°C), that all six years are virtually tied.

但是僅一年的排名能說(shuō)明什么問(wèn)題呢？并沒(méi)有太大價(jià)值，戈達(dá)德太空研究所的主任James Hansen說(shuō)。在他小組的分析中，2010年的平均氣溫只比2005年低了不到0.01攝氏度（0.018華氏度），如果考慮到計(jì)算統(tǒng)計(jì)中的誤差，這點(diǎn)相差可以忽略。同時(shí)，歷史上第三溫暖的年份——2009年與1998、2002、2003、2006和2007年的平均氣溫最大相差只有0.03攝氏度；可以說(shuō)，這六年的氣溫實(shí)際上是一樣的。

What matters more than a yearly record from a single group is the longer trend, as shown in the plot at the top of this page. The four records are unequivocal: the world has warmed since 1880, and the last decade has been the warmest on record.

比研究一年一年的記錄更有價(jià)值的是研究長(zhǎng)期的趨勢(shì)，正如本文一開(kāi)始所展示的圖表。四個(gè)研究所的數(shù)據(jù)明確的說(shuō)明了地球從1880年溫度開(kāi)始逐年上升，近十年是記錄上最溫暖的年份。

When we focus on the annual rankings, the differences between the temperature analyses can be confusing. For example, GISS previously ranked 2005 as the warmest, while the Met Office listed 1998. The discrepancy helped fuel a misconception that findings from the research groups varied sharply or contained large degrees of uncertainty. It also fueled a misconception that global warming had stopped in 1998.

當(dāng)我們把注意力放在年份的排名上時(shí)，數(shù)據(jù)分析間的不同很讓人迷惑。例如GISS之前的記錄表明2005年是最溫暖的一年，而英國(guó)氣象局的記錄是1998年。這樣的分歧加劇了人們對(duì)于氣象研究數(shù)據(jù)的誤解。他們往往認(rèn)為不同研究所得研究結(jié)果有很大的差別并且有著相當(dāng)?shù)牟淮_定性。甚至還有人認(rèn)為全球變暖在1998年就已經(jīng)停止了。

“The official records vary slightly because of subtle differences in the way we analyze the data,” said Reto Ruedy, one of Hansen’s colleagues at GISS. “But they also agree extraordinarily well.”

“這些官方數(shù)據(jù)間微小的差別產(chǎn)生的主要原因是數(shù)據(jù)分析方法間的微妙差別，”Hansen在GISS的同事Reto Ruedy說(shuō)，“但大體上還是一致的。”

All four records above show peaks and valleys in sync with each other. All show particularly rapid warming in the past few decades. And all show the last decade as the warmest.

以上的四組數(shù)據(jù)所展示的峰和谷都是一致的。他們都表明溫度在最近的幾十年中上升的速度很快以及近十年是歷史上最溫暖的十年。

The small discrepancies between the records are mostly due to the way scientists from each institution handle regions of the world where temperature-monitoring stations are scarce—parts of Africa, Antarctica, the Arctic, and the Amazon. For instance, GISS fills in the gaps (see the first global map above) with data from the nearest land stations. The Met Office analysis (second of the two global maps above) leaves areas of the Arctic Ocean out.

這些數(shù)據(jù)間的小差異大多是由于不同研究所在處理一些邊遠(yuǎn)地區(qū)氣候數(shù)據(jù)的方法不同而導(dǎo)致的。這些地方的氣象站很稀少，包括非洲的部分地區(qū)、南極洲、北極和亞馬遜雨林。例如，GISS記錄最近的陸地上的氣象站的數(shù)據(jù)（見(jiàn)第一張世界地圖）；英國(guó)氣象局的數(shù)據(jù)則未包括北極（見(jiàn)第二張世界地圖）

Both approaches pose problems. By not inferring data, the Met Office assumes that the areas without stations have a warming equal to that of the entire Northern Hemisphere—a value that satellite and field measurements suggest is too low, given the observed rate of Arctic sea ice loss. On the other hand, GISS’s approach may either overestimate or underestimate Arctic warming.

這兩種方法都有問(wèn)題。英國(guó)氣象局的方法是不估測(cè)數(shù)據(jù)，沒(méi)有氣象站的地區(qū)用整體北半球的暖化程度來(lái)代替。整體北半球的暖化程度是由衛(wèi)星和地球上的一系列的測(cè)量計(jì)算出的。這個(gè)值往往偏低，因?yàn)楫?dāng)中含有北極冰塊的消融。另一方面，GISS的方法也不能對(duì)北極的暖化程度有一個(gè)準(zhǔn)確的反映。

“There’s no doubt that estimates of Arctic warming are uncertain, and should be regarded with caution,” Hansen said. “Still, the rapid pace of Arctic ice retreat leaves little question that temperatures in the region are rising fast, perhaps faster than we assume in our analysis.”

“毫無(wú)疑問(wèn)，對(duì)于北極暖化得現(xiàn)象的估計(jì)是不確定的，所以應(yīng)該謹(jǐn)慎評(píng)估，”Hansen說(shuō)。“然而，北極冰塊融化的速度逐漸加快也表明該地區(qū)的溫度在迅速升高，速度可能超過(guò)我們?cè)诜治鰣?bào)告里的假設(shè)。”

The temperature records also differ slightly because the point of reference that each group uses to calculate global temperature is different. It is not possible to reliably calculate absolute global average surface temperatures, so scientists instead calculate a relative measure called a “temperature anomaly.” They compare average temperatures at any given time and place to a long-term average, or base period, for each area. GISS uses a base period of 1951 to 1980; the Met Office uses 1961 to 1990; the Japanese Meteorological Agency uses 1971 to 2000; and NCDC uses the entire 20th century.

溫度的記錄間的細(xì)微差別的原因還有一點(diǎn)是不同研究所運(yùn)用的測(cè)量溫度的參考不一樣。要直接得到真實(shí)的全球地表氣溫是不太可能的，所以科學(xué)家們要在計(jì)算結(jié)果中加入“氣候異常”的因素。在每個(gè)地區(qū)，他們都用一個(gè)時(shí)間點(diǎn)的平均氣溫和長(zhǎng)期或者一段時(shí)間內(nèi)的平均氣溫進(jìn)行比較。GISS用的是1951年到1980年的氣溫?cái)?shù)據(jù)；英國(guó)氣象局用的是1967年到1990年的氣溫?cái)?shù)據(jù)；日本氣象廳用的是1971到2000年的氣溫?cái)?shù)據(jù)；NCDC用得失整個(gè)20世紀(jì)的氣候數(shù)據(jù)。

This means that numerical values of the temperature anomalies differ. But it does not change the magnitude of temperature changes over the past century.

這意味著：盡管在數(shù)字上這些溫度反常會(huì)不一樣，但是上世紀(jì)氣溫變化的總量是不會(huì)變化的。

NASA images by Robert Simmon, based on data from the NASA Goddard Institute for Space Studies, NOAA National Climatic Data Center, Met Office Hadley Centre/Climatic Research Unit, and the Japanese Meteorological Agency. Caption by Adam Voiland and Mike Carlowicz.

制圖/Robert Simmon

數(shù)據(jù)來(lái)源/NASA Goddard Institute for Space Studies, NOAA National Climatic Data Center, Met Office Hadley Centre/Climatic Research Unit, and the Japanese Meteorological Agency

文字說(shuō)明/Adam Voiland and Mike Carlowicz