图片来源/New York Times
有生之年里，人类可能要完蛋了？
本文约3700字
上周一，各大西方主流媒体纷纷头条报道了联合国发布的《全球升温1.5℃特别报告》。这份重量级科学报告向世界各国领导人和人类发布了最后警报：人类必须在2040年之前控制气候升温低于1.5℃，否则后果将不堪设想。
A landmark report from the United Nations’ scientific panel on climate change paints a far more dire picture of the immediate consequences of climate change than previously thought and says that avoiding the damage requires transforming the world economy at a speed and scale that has “no documented historic precedent.”
上周一，联合国气候变化科学委员会发布了一份具有里程碑意义的气候变化报告。该报告描绘了气候变化带来的直接恶果的图景，远比之前想象的惨烈。报告同时称：若想避免灾难，人类须以“史无前例”的速度与规模转变世界经济。
The report, issued on Monday by the Intergovernmental Panel on Climate Change, a group of scientists convened by the United Nations to guide world leaders, describes a world of worsening food shortages and wildfires, and a mass die-off of coral reefs as soon as 2040 — a period well within the lifetime of much of the global population.
由政府间气候变化专门委员会发布的报告称，最快在2040年，世界粮食短缺与野外火灾情况会不断恶化，同时有大批量珊瑚礁相继死亡。这些恶果发生时，许多世界现有人口仍然在世。
注：政府间气候变化委员会(IPCC)：由联合国召集、给各国领导人提出建议的科学家团
The authors found that if greenhouse gas emissions continue at the current rate, the atmosphere will warm up by as much as 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels by 2040, inundating coastlines and intensifying droughts and poverty. Previous work had focused on estimating the damage if average temperatures were to rise by a larger number, 3.6 degrees Fahrenheit (2 degrees Celsius), because that was the threshold scientists previously considered for the most severe effects of climate change.
作者发现，如果温室气体排放仍维持在现有速率，到2040年大气温度将比工业化以前高出2.7华氏度(1.5摄氏度)之多，进而淹没海岸线地带，加剧干旱和贫困问题。科学家先前的工作一直集中在估测平均温度上升3.6华氏度(2.0摄氏度)后形成的损害，因为这是他们原本以为的引起最严重气候变化效应的临界值。
The new report, however, shows that many of those effects will come much sooner, at the 2.7-degree mark.
How serious can the change be if we don’t take urgent action
如果我们不采取紧急行动，气候变化会有多严重?
图片来源/IPCC《全球升温1.5℃特别报告》
The report makes it clear that climate change is already happening -- and what comes next could be even worse, unless urgent international action is taken.
"One of the key messages that comes out very strongly from this report is that we are already seeing the consequences of 1 degree C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice, among other changes," said Panmao Zhai, co-chair of IPCC Working Group I.
Even if warming is kept at or just below 1.5 degrees C, the impacts will be widespread and significant.
Temperatures during summer heatwaves, such as those just experienced across Europe this summer, can be expected to increase by 3 degrees C says the report.
More frequent or intense droughts, such as the one that nearly ran the taps dry in Cape Town, South Africa, as well as more frequent extreme rainfall events such as hurricanes Harvey and Florence in the United States, are also pointed to as expectations as we reach the warming threshold.
Coral reefs will also be drastically affected, with between 70 and 90% expected to die off, including Australia's Great Barrier Reef.
珊瑚礁也将受到严重影响，预计有70%到90%的珊瑚礁将消失，其中包括澳大利亚的大堡礁。
Countries in the southern hemisphere will be among the worse off, the report said, "projected to experience the largest impacts on economic growth due to climate change should global warming increase."
南半球国家的情况将更糟，“如果全球变暖加剧，该地区的经济增长预计将遭受最大打击。”
The report underlines how even the smallest increase in the base target would worsen the impact of recent natural disasters.
报告强调，即使是气温在基数之上增加一点点，也会加剧近期自然灾害的影响。
"Every extra bit of warming matters, especially since warming of 1.5 degrees C or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems," said Hans-Otto Pörtner, Co-Chair of IPCC Working Group II.
IPCC第二工作组的联合主席汉斯·奥托波特纳表示：“气温每升高一点都会带来严重后果。尤其当气温增幅大于等于1.5摄氏度时，长期或不可逆转的变化带来的风险会大幅增加，比如一些生态系统的破坏。”
The report cites specific examples of how impacts of global warming would be lessened with the 1.5 degrees C increase, compared to the 2 degrees C increase:
报告援引具体的例子来说明，和气温上升2摄氏度相比，全球变暖的影响是如何随着气温上升1.5摄氏度而减轻的：
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This chart from the IPCC shows how global temperatures would respond to a sudden and drastic reduction of greenhouse gas emissions. Even with immediate action, global temps will still overshoot the goal, but could reduce back to the target over time.
IPCC的这张图表显示了温室气体排放突然大幅减少对全球气温的影响。即使人类立即采取行动，全球气温仍然会超过目标值。但随着时间推移，全球气温可以降低回目标值。图片来源/CNN
What needs to be done: the controversies
需要做的事：解决争论
Avoiding the most serious damage requires transforming the world economy within just a few years, said the authors, who estimate that the damage would come at a cost of $54 trillion.
报告表明，为避免严重的气候损害，世界经济需要在短短几年间转变，否则可能造成高达540亿美金的损失。
The report shows that there are two main ways of removing carbon from the atmosphere: increasing natural processes that already do this, and experimental carbon storage or removal technologies.
该报告还提出，降低大气碳含量的方式主要有两种：一是促进已有的减少大气碳含量的自然过程，二是采用仍在试验阶段的碳存储和碳移除技术。
But while they conclude that it is technically possible to achieve the rapid changes required to avoid 2.7 degrees of warming, they concede that it may be politically unlikely.
研究小组认为完成经济上的快速转变，并避免2.7摄氏度的升温在技术上是可行的，但他们也承认在政治上难以实现这种转变。
For instance, the report says that heavy taxes or prices on carbon dioxide emissions — perhaps as high as $27,000 per ton by 2100 — would be required. But such a move would be almost politically impossible in the United States, the world’s largest economy and second-largest greenhouse gas emitter behind China. Lawmakers around the world, including in China, the European Union and California, have enacted carbon pricing programs.
比如，报告指出，各国必须针对碳排放收取高额税收或增价——预计到2100年将达到27,000美元（合计约186710.4元）每吨。但对于世界第一大经济体和第二大温室气体排放国的美国来说，这样的政策几乎不可能推行。而在世界范围内，中国、欧洲和加利福尼亚的立法者都已经制定了有关碳排放收费的法律。
President Trump, who has mocked the science of human-caused climate change, has vowed to increase the burning of coal and said he intends to withdraw from the Paris agreement. And on Sunday in Brazil, the world’s seventh-largest emitter of greenhouse gas, voters appeared on track to elect a new president, Jair Bolsonaro, who has said he also plans to withdraw from the accord.
特朗普总统对有关人为气候变化的科学研究不以为然。他宣布美国要增加煤炭的燃烧量，并宣称美国将退出巴黎协定。无独有偶，本周日，在世界温室气体排放第七大国的巴西，选民们似乎有意选举新任巴西总统为杰尔·波索纳洛，而杰尔·波索纳洛也曾宣称有意退出巴黎协定。
特朗普誓言增加煤炭的燃烧，并称其打算退出巴黎协定。图片来源/New York Times
At the current level of commitments, the world is on course for a disastrous 3C of warming.
就目前各国作出的承诺来看，全球气温很可能会上升3摄氏度——这将是灾难性的。
But the report authors are refusing to accept defeat, believing the increasingly visible damage caused by climate change will shift opinion their way.
但此报告的作者们拒绝认输，他们坚信气候变化带来的危害会更加显而易见，从而使得他们的观点变成主流。
“I hope this can change the world,” said Jiang Kejun of China’s semi-governmental Energy Research Institute, who is one of the authors.
此份报告的作者之一，来自中国半官方能源研究所的姜克隽说，“我希望这能够改变世界。”
“Two years ago, even I didn’t believe 1.5C was possible but when I look at the options I have confidence it can be done.
“两年前，我甚至不相信气温有可能只升高1.5摄氏度。但当看到今天有这么多的选择，我有信心一定可以做到。
"I want to use this report to do something big in China.”
我想用这篇报告在中国大有作为。”
The timing was good, he said, because the Chinese government was drawing up a long-term plan for 2050 and there was more awareness among the population about the problem of rising temperatures.
姜克隽说，当下时机正好，因为中国政府正在为2050年勾勒长期发展的蓝图并且国民对温度上升产生的问题也有了越来越多的认识。
“People in Beijing have never experienced so many hot days as this summer. It’s made them talk more about climate change.”
“住在北京的人从来没有经历过像今年夏天这么长的高温天气。这让他们更加频繁地提及气候变化这个话题。
Regardless of the US and Brazil, he said, China, Europe and major cities could push ahead.
他说，不管美国和巴西如何，中国、欧洲和主要城市会一直向前推进。
“We can set an example and show what can be done. This is more about technology than politics.”
“我们可以做出表率并且展示出可达成的目标。这关乎科技但更关乎政策。”
资料来源：
https://www.nytimes.com/2018/10/07/climate/ipcc-climate-report-2040.html?action=click&module=Top%20Stories&pgtype=Homepage
https://edition.cnn.com/2018/10/07/world/climate-change-new-ipcc-report-wxc/index.html
https://www.theguardian.com/environment/2018/oct/08/global-warming-must-not-exceed-15c-warns-landmark-un-report
https://www.theguardian.com/science/scienceofclimatechange
资料整合|张殷雯
编译|苏娟、陈宁、
张进宁、常慧、徐炜
排版|陈宁、张殷雯