聯(lián)合國氣候報告反復(fù)強調(diào)，要把全球升溫幅度控制在1.5℃以內(nèi)。此前《巴黎協(xié)定》提出的目標(biāo)是，要把升溫幅度控制在2℃以內(nèi)，同時盡力不超過1.5℃。那么，全球升溫1.5℃和 2℃的區(qū)別到底有多大？

Over and over at the UN climate summit in Glasgow， world leaders have stressed the need to limit global warming to 1.5℃.

The 2015 Paris Agreement commits countries to limit the global average temperature rise to well below 2℃ above pre-industrial levels， and to aim for 1.5℃.

Scientists? have said crossing the 1.5℃ threshold risks unleeshin6 far more severe climate change effects on people， wildlife and ecosystems.

But what is the difference between 1.5℃ and 2℃ of global warming？

Already， the world has heated to around 1.1℃ above pre-industrial levels. Each of the last four decades was hotter than any decade since 1850.

“We never had such a global warming in only a few decades，” said climate scientist Daniela Jacob at the Climate Service Center Germany.“Halfa? degree? means? much? more? extreme weather， and it can be more intense， or extended in duration.”

在英國格拉斯哥舉行的聯(lián)合國氣候變化大會上，世界各國領(lǐng)導(dǎo)人反復(fù)強調(diào)，必須把全球升溫幅度控制在1.5℃以內(nèi)。

2015年達(dá)成的《巴黎協(xié)定》中，各國政府承諾將全球平均溫度控制在比前工業(yè)化水平升溫2℃以內(nèi)，并努力達(dá)到升溫1.5℃以內(nèi)的目標(biāo)。

科學(xué)家指出，升溫幅度超過1.5℃意味著人類、野生動植物和生態(tài)系統(tǒng)都可能遭受氣候變化帶來的更嚴(yán)重后果。

但全球升溫1.5℃和2℃有什么不同呢？

當(dāng)前，全球溫度已經(jīng)比前工業(yè)化水平高出約1.1℃。過去四個十年的氣溫比1850年以來的任何一個十年都更高。

德國氣候服務(wù)中心的氣候科學(xué)家丹妮拉·雅各布說：“僅僅數(shù)十年就升溫這么多，這樣的全球變暖是從未發(fā)生過的。升溫0.5℃意味著更極端的天氣會更頻繁地出現(xiàn)，而且極端天氣會更惡劣或持續(xù)更長時間?！?/p>

“Climate change is already affecting every inhabited region across the globe，” said climate scientist Rachel Warren at the University of East Anglia in Britain.

More warming to 1.5℃ and beyond will worsen such impacts . For example， heatwaves would become both more frequent and more severe.

A warmer atmosphere can also hold more moisture， resulting in more extreme rainfall that raises flood risks . It also increases evaporation， leading to more intense droughts.

“At 1.5℃， there's a good chance we can prevent most of the Greenland and west Antarctic ice sheet from collapsing，” said climate scientist Michael Mann at Pennsylvania State University in the US.

But blow past 2℃ and the ice sheets could collapse， Mann said， with sea levels rising? up to 10 meters — though? how quickly that could happen is uncertain.

Warming of 1.5℃ would destroy at least 70% of coral reefs， but at 2℃ more than 99% would? be lost . That would destroy fish habitats and communities that rely on reefs for their food and livelihoods.

英國東英吉利亞大學(xué)的氣候科學(xué)家瑞秋·沃倫說：“氣候變化已經(jīng)影響到了人類居住的每個角落?！?/p>

全球升溫超過1.5℃將會加劇氣候變化的影響。比如，高溫將會更頻繁地來襲，程度也會更嚴(yán)重。

氣溫升高還會讓大氣聚集更多水汽，引發(fā)更多強降雨，從而增加洪水風(fēng)險。氣溫升高還會使得蒸發(fā)量增加，從而導(dǎo)致更嚴(yán)重的干旱。

美國賓夕法尼亞州立大學(xué)的氣候科學(xué)家邁克爾·曼恩說：“如果升溫幅度在1.5℃以內(nèi)，我們還有可能防止格陵蘭島和南極西部的大部分冰蓋融化崩塌。”

曼恩說，但是如果升溫幅度超過2℃，冰蓋就會瓦解，海平面會上升10米之多。不過，不確定這一天來得會有多快。

全球升溫1.5℃會摧毀至少70%的珊瑚礁，升溫2℃則會使得超過99%的珊瑚礁死亡。這對于依賴珊瑚覓食和棲息的魚群來說是一個毀滅性打擊。

Warming of 2℃， versus 1.5℃， would also increase the impact on food production.

“If you have crop failures in a couple of the breadbaskets of the world at the same time， then you could see extreme food price spikes and hunger and famine across wide swathes of the world，” said climate scientist Simon Lewis at University CollegeLondon.

A warmer world could see the mosquitoes that carry diseases such as malaria and dengue fever expand across a wider range. But 2℃ would also see a bigger share of insects and animals lose most of their habitat range， compared with 1.5℃， and increase the risk of forest fires—another risk to wildlife.

As the world heats up， the risk increases that the planet will reach “tipping points” ， where Earth's systems cross a threshold that triggers irreversible or cascading impacts. Exactly when those points would be reached is uncertain.

全球升溫由1.5℃到2℃，還會加大對糧食生產(chǎn)的影響。

倫敦大學(xué)學(xué)院的氣候科學(xué)家西蒙·路易斯說：“如果世界上的幾個糧食主產(chǎn)地同時發(fā)生農(nóng)作物歉收，大范圍的食品價格飛漲和饑荒將會席卷全球?！?/p>

全球變暖會導(dǎo)致攜帶瘧疾和登革熱病毒的蚊蟲大范圍滋生。相比升溫1.5℃，升溫2℃會讓更多昆蟲和動物失去大部分棲息地，還會增加森林火災(zāi)風(fēng)險，進(jìn)而危及野生動植物的生存。

隨著全球變暖，地球達(dá)到“臨界點”的風(fēng)險也會增加。一旦到達(dá)這個臨界點，就會觸發(fā)地球系統(tǒng)不可逆轉(zhuǎn)的連鎖效應(yīng)。但具體何時到達(dá)臨界點還不確定。”

Word Study

unleash /?n'li??/ v.突然釋放；使爆發(fā)

collapse /k?'l?ps/ v.崩塌；崩潰

The roof collapsed under the weight of snow.

price spike 價格飆升；價格激增