與很多人感受的一樣，這個夏季全國平均氣溫僅次于1961年，是有紀錄以來的歷史第二高，而且北京等地單日氣溫測出了歷史新高，40攝氏度以上已不鮮見；與很多人感受的不同，這個夏季平均降雨量并不大，但雨水在時間與空間上都高度集中，引發(fā)了洪澇與干旱并存的場景。再加上臺風(fēng)、雷暴、風(fēng)雹、龍卷風(fēng)等災(zāi)害天氣的出現(xiàn)，“極端”可以說是2023年夏天的第一關(guān)鍵詞。

To pick a key word for summer 2023, “extreme” must be a top candidate. We’ve had an average temperature of 22℃, the highest in recorded history except other than 1961. The rainfall has been limited but also concentrated, so much so that Beijing saw its heaviest rainfall since 2012 while some regions in the Northwest suffered from drought.

從過去幾個不幸很熱的夏天中總結(jié)經(jīng)驗，我們似乎發(fā)現(xiàn)，每個極熱的夏天背后都跟著一個極冷的冬天。那么2023年的冬天會很冷嗎？

Unfortunately, experience from the past several years show that after every extremely hot summer there follows an extremely cold winter. So what about the winter in 2023? Will it be extremely cold?

氣候極端化、天氣波動加大

與所有專家一樣，中國氣象局公共氣象服務(wù)中心原氣象服務(wù)首席專家朱定真教授并不愿意給這個問題一個“是”或者“否”的確定答案，畢竟2023年的冬天尚未到來。但可以確定的是，夏天極熱、暴雨極強、冬天極冷其實是反映的是一回事，都是氣候趨于極端化的表現(xiàn)。
For Zhu Dingzhen, retired chief expert for meteorological services at China Meteorological Administration Public Meteorological Service Center, it’s hard to answer with a definite “yes”, but the probability is very high. “There is no direct link between the temperatures of summer and winter,” he said, “but when the former is extremely high that’s a sign of the total climate system being turbulent, which means the latter has a much higher possibility of being extremely low.”

“極端的冷也好、熱也好、旱澇也好，都是大氣環(huán)流紊亂造成的，”朱定真表示，“夏天能熱出新高度說明我們的氣候的極端化程度加重了，這種背景下如果冬天冷出新紀錄也并不奇怪。”

就好比單擺，如果擺錘在一端擺幅已經(jīng)很大，那在另一端也可能會很大，因為整個單擺的閾值已經(jīng)提高了。但在擺錘沒有擺到另一邊之前，誰也沒法給出肯定的答案。

The climate radicalization is like a swinging pendulum — the left side is swinging at a higher amplitude, so it’s possible the right side might swing higher too, although no one can be 100 percent sure.

值得注意的是，冬天冷出新紀錄指的并不是平均氣溫低，而是指波動的單日氣溫可能很低。2021年北京冬天單日氣溫最低值打破歷史紀錄，但從整個冬天的平均溫度來看依然是暖冬。地球整體在升溫，每日氣溫的波動幅度、范圍、頻率都在變得更大。

朱定真教授特別提醒：“暖冬是個氣候概念，不等于冬季每天都很暖和，全球氣候極端化的背景下，暖冬里也很容易出現(xiàn)極端寒潮天氣事件，該做的防寒工作一定要做！”

Zhu stressed that extreme cold is more about weather than climate, referring to single-day temperatures rather the average temperatures of the whole season. A good example is the “warm winter” in Beijing 2021, which saw the lowest single-day temperature in history. “Warm winter doesn’t mean being warm every day,” Zhu warned: “especially with climate change intensifying, there might be quite frequent cold waves in warm winters, so one must always take caution.”

對“大氣環(huán)流紊亂”這個說法，中國科學(xué)院大氣物理研究所副研究員陳衛(wèi)博士給出了進一步的解釋。她拿出地球儀，演示了這一過程：

地球是赤道熱兩極冷，氣流自然會從熱帶亞熱帶的高壓地區(qū)往極地低壓地區(qū)流動。受地轉(zhuǎn)偏向力的作用，這一氣流在北半球中緯度向右偏轉(zhuǎn)為西風(fēng)。正常情況下，極地的“冷”與赤道的“暖”之間存在明顯的南北溫度梯度，這使得西風(fēng)帶很強盛，存在于其中的環(huán)流也很穩(wěn)定，起到阻擋北極冷空氣南下的重任。

Chen Wei, an associate researcher at Institute of Atmospheric Physics, Chinese Academy of Sciences, explained that further in terms of the global atmosphere movement. As the air pressure near the ground is higher in hot tropical regions than in cold poles, there is always a constant air flow from the former to the latter that turns right in the northern hemisphere and becomes western wind in the middle latitude. “Such western wind is a protection wall that turns any cold wave from the north into western wind, thus preventing it from going further south,” Chen said.

但隨著全球變暖加劇，北極增暖更為明顯，與赤道間的溫度梯度減弱，導(dǎo)致西風(fēng)帶減弱，極地渦旋變得不穩(wěn)定，極渦內(nèi)的冷空氣分裂南下，寒潮就能大舉南侵。所以，雖然全球溫度在升高，我們冬天感受到的寒潮反而更強。全球變暖與極冷天氣不沖突，緣由在此。

However, with climate change, the temperature in the arctic region is growing so the temperature gap with the celestial equator shrinks. Chen pointed out that this weakens the western wind in middle latitude regions thus weakening its ability to prevent cold waves from going south, which, combined with the increasingly frequent unstable polar vortex that unleashes more cold waves, the frequency of cold weather naturally gets higher.

更可怕的還在后邊。結(jié)滿了冰的北極本來像面大鏡子，能把照射來的絕大部分太陽光線反射回太空，但隨著海冰融化鏡子越來越弱，反照率越來越低，于是融化的更快，導(dǎo)致北極以兩倍于其他地區(qū)的速度增暖，稱之為“北極增暖放大”現(xiàn)象，這一惡性循環(huán)一旦開啟情況只會越來越壞。很多人都看過一張著名的照片，融化的浮冰上趴著一只瘦骨嶙峋的北極熊，在全球變暖趨勢被逆轉(zhuǎn)之前，這一情況只會越來越明顯。

In worse conditions the process can turn into a vicious circle. The huge piles of ice in the Arctic are like a big mirror that reflects part of the solar rays back into space, but as they melt the reflection gets weaker so more heat is accumulated, accelerating the meltdown process, which in turn further weakens the reflection. Chen said that this is called the “Arctic amplifying effect”, a process which has already begun and won’t be reversed until humankind pulls the brake on global warming activities.

災(zāi)難性天氣，不只是說說而已

波動多了出問題的可能性自然就越高。9月初中國氣象臺發(fā)布的官方報告中，清楚地給2023年的夏天做了總結(jié)：“暴雨過程頻繁，華北、東北等地強降水引發(fā)嚴重洪澇災(zāi)害，出現(xiàn)明顯‘旱澇急轉(zhuǎn)’；臺風(fēng)生成和登陸個數(shù)少，但破壞力強，“杜蘇芮”導(dǎo)致嚴重洪澇災(zāi)害；高溫日數(shù)多，極端性強；短時強降雨、雷暴、風(fēng)雹、龍卷等災(zāi)害多點散發(fā)，致災(zāi)性強?！?/p>

“Heavy rainfalls are getting more frequent and have caused severe flooding in North and Northeast China, causing U-turns between droughts and floods. Typhoons are few in number but more destructive in force, of which Typhoon Doksuri had caused heavy flooding. There are more days with high temperatures, of which some are highly extreme. More catastrophes such as short-term strong rainfall, lightening storm and hurricane are located more widely.”

京津冀特大暴雨霸屏熱搜榜時，西北內(nèi)陸正遭受旱災(zāi)，說這個夏天多災(zāi)多難一點都不夸張。中國人民大學(xué)生態(tài)文明研究院副院長王克教授指出，這種災(zāi)難是全方面的，甚至可以說是左右為難。

“過冷和過熱都會導(dǎo)致一些慢性病發(fā)病率上升；極端天氣下很多工程不得不停工，即使不停工效率也會低很多；糧食作物會因為極寒或者極冷而減產(chǎn)，從而危害糧食安全；暴雨與內(nèi)澇會在城市造成巨大的傷亡與財產(chǎn)損失，為防范這些損失又需要花巨資升級城市基礎(chǔ)設(shè)施，這些都是成本?！?/p>

While for urban residents, a “weather catastrophe” might mean inconveniences of travelling or having to stay at home, for agricultural production that may mean actual losses. Some outdoor construction or engineering projects have to suspend or face lower efficiency in cold or hot weather;Crops might wither in extreme cold or die in heat, thus posing a bigger challenge to the national food security;The cities have to either face losses of floods or raise the standards of buildings to withstand such floods, both of which cost money.

對于城市居民來說，氣候災(zāi)難可能意味著忽冷忽熱的氣溫、意味著街道上的積水、意味著下大雨無法出門而遲到被扣錢。但對農(nóng)業(yè)生產(chǎn)來說，氣候災(zāi)難給人的感受可能更深。西瓜、早稻等夏天成熟的作物都需要在早春育苗，一場寒潮來襲，人在室內(nèi)能夠躲過去，但可能地里就不再有存活的秧苗。早在2006年4月，湖南寧鄉(xiāng)縣就遭遇了氣溫劇降伴隨大風(fēng)的強寒潮，當?shù)卦绲狙砻缙毡榍嗫?、發(fā)黃，甚至死苗，而過去17年里氣候極端化程度可不止加劇了一點半點，寒潮襲擊的新聞頻繁許多。

很多人在網(wǎng)上看到過“全球變暖的十大好處”之類的帖文，這些帖文圖文并茂、繪聲繪色地講述著西北內(nèi)陸如何變得濕潤，一些熱帶亞熱帶水果種植線如何北移，曾經(jīng)的沙漠如何變成綠洲。陳衛(wèi)博士表示，畢竟大氣升溫后能容納的水汽增多了，全球降水不確定性增大，曾經(jīng)干旱的地區(qū)迎來更多強降雨并非不可能。

There have been doubts and challenges that climate change is a lie. There were even some articles that went viral carrying headlines such as “10 benefits of global warming”, which claim that with the global warming process, some tropical or sub-tropical fruits would be able to be planted in northern regions while northwestern dry regions would become wet.

但是干旱地區(qū)多出來的降雨會很有限，因為大氣輸送水汽能力有限，將水汽運送到內(nèi)陸損耗是很大的，指望這種極端天氣帶來的降水讓沙漠變綠洲不現(xiàn)實。反而是本來就濕潤的沿海地區(qū)會迎來更極端的降雨，甚至?xí)霈F(xiàn)海岸線上升、整座城市被淹沒的末日場景。跟這些損失比起來，沙漠多出來的那點毛毛雨真的不算什么……

沙漠發(fā)洪水，就能變綠洲嗎？

那怎么解釋塔克拉瑪干沙漠發(fā)洪水呢？2021年7月的視頻在網(wǎng)上已經(jīng)流傳兩年之久，洪水在沙漠里蔓延、駱駝游泳逃生是實實在在的。朱定真教授揭開了“沙漠發(fā)洪水”現(xiàn)象背后的真相：降水只占一部分，導(dǎo)致洪水的還有高原冰蓋加速融化的雪水！這可不是好事，雪山冰川是人類淡水的主要儲備，也是人類多條大江大河的發(fā)源地。這么加速融下去，人類的水塔就干涸了。

2022年，也就是塔克拉瑪干沙漠發(fā)洪水的第二年，世界水源地峰會發(fā)起人楊勇考察了長江源等幾條國內(nèi)主要河流的源頭。他發(fā)現(xiàn)，在原本應(yīng)該是豐水期的七八月，這里卻有大片沙灘裸露著。長江、雅魯藏布江、印度河、恒河都會受到影響。

甚至早在五年前，位于烏魯木齊的中國科學(xué)院天山冰川觀測試驗站就觀測到一組令人憂心的數(shù)據(jù)。在2016年4月到2017年4月間，1號冰川的東西兩支分別退縮6.3米和7.2米，其中西支退縮速率為1993 年1號冰川分裂以來的最大值。

As early as April 2017, the Tianshan Mountain Glacier Observatory found that two branches of the No.1 glacier in that area had retreated by 6.3 and 7.2 meters respectively, of which the western branch saw its biggest retreat since its formation in 1993.

夏天極熱、冬天極冷，旱的旱死、澇的澇死，海冰消融，大河枯水，這些問題有些初現(xiàn)端倪、有些則已經(jīng)十分嚴重，而這一切的原因只是在過去幾百年碳排放的積累效應(yīng)下，因為地球平均氣溫上升了一度半度。

2022年9月，牛津大學(xué)在一份報告中指出，截止2050年全球氣候變化可能將造成高達23萬億美元的經(jīng)濟損失。要知道，中國2022年GDP才不過18萬億美元。

In September 2022, a study by Oxford University researchers published on Joule, an online research magazine on global challenges, estimated that if the current trend continues, global climate change might cause a loss of $23 trillion by 2050. As a comparison, China’s GDP in 2022 was only $18 trillion.

2009年的哥本哈根會議設(shè)定了目標，要在本世紀末將全球升溫限定在2攝氏度以內(nèi)，2015年巴黎會議再度確認了這一與人類生死存亡相關(guān)的目標，但沒有達成任何有約束力的協(xié)議。直到今天，中國“雙碳”目標提出已久，各發(fā)達國家還在為誰分配多少碳排放額、誰提供多少補貼推諉扯皮。

It’s hard to imagine what would happen if the global temperature rises by 2 degrees, which is the dead limit set by Copenhagen Climate Change Conference in 2009 and stressed again by the Paris Conference in 2015. Unfortunately, even that goal will be hard to achieve because some key clauses of the Paris Agreement, such as the one about nationally determined contributions, are voluntary instead of legally binding, which means the participants have the choice to implement it or not as they wish.

王克教授特別指出，“氣候極端化的進程是非線性的，大自然不會給人類留下太多的時間去適應(yīng)。”2023年夏天，僅在北京就有29.7天氣溫超過35攝氏度，比往年平均數(shù)直接多出21.1天，且有5天超過40攝氏度，是非常危險的信號。

留給人類的時間不多了。