Arctic summers could be ice-free once a decade in a two-degree world, but once a century in a one-and-a-half-degree one. 如果平均温度上升2°C，北极夏季可能十年就有一次不结冰，但是若平均温度上升1.5°C，就可能一个世纪一次。

Virtually all the ocean's coral might be irreversibly wiped out in a two-degree world, rather than 70-90% if temperatures rise by less. 平均温度上升2°C，几乎所有的海洋珊瑚都可能不可逆转地消亡，而如果温度上升的幅度小些，消亡数量可能减至70-90%。

Sea levels may rise an extra 10cm, washing away the livelihoods of millions more people. 海平面可能会再上升10厘米，使数百万人失去生命。

Permitting a rise of two degrees could also see an extra 420m people exposed to record heat. 如果允许气温上升2°C，还会有4.2亿人遭受创纪录的高温。

The 2°C target has been baked into climate policy for years— 多年来，气候政策都定为允许气温上升2°C——

the number was first put forward by William Nordhaus, who shared the Nobel economics prize this week. 但2°C的目标太松了。

It is too lax. 威廉·诺德豪斯第一次提出这个数字，他在本周共享诺贝尔经济学奖。

Hitting either target would entail transforming economies at a breakneck pace. 无论要达成哪一目标，都要求经济以极快速度转型。

To achieve 1.5°C, the world would by 2050 need to eliminate all 42bn tonnes of carbon-dioxide in annual emissions. 要达到控制温度上升不超过1.5°C的目标，到2050年，全球每年排放的420亿吨二氧化碳需要全部消除。

Renewables, including hydropower, would have at least to treble their share of electricity generation from today’s 25%. 包括水力发电在内的可再生能源在发电量中所占的比例至少要从目前的25%提高两倍。

Internal-combustion engines, which power 499 out of 500 cars on the road today, would have to all but vanish. 内燃机驱动汽车也得消失，如今，在公路上行驶的500辆汽车中，有499辆是由内燃机驱动的。

Progress is being made. 但我们也正逐步取得进展。

The number of electric cars on the road is rising fast; 路上的电动汽车数量正在迅速增加；

green finance is gathering momentum; 绿色金融蓄势待发；

zero-carbon technologies are being developed. 零碳技术正在开发中。

But the scale of the effort required is unprecedented. 但所需的努力规模是前所未有的。

That is why reaction to the IPCC's report matters. 这就是为什么对IPCC报告的反应很重要。

Some European Union environment ministers want to adopt 1.5°C as a guide to policy before a UN summit in Poland in December. 12月份，在联合国波兰峰会前，某些欧盟环境部长想采用1.5°C作为政策指导。

Their Australian counterpart called it "irresponsible" to phase out coal by 2050. 其澳大利亚同行称到2050年逐步淘汰煤炭是“不负责任的”。

Donald Trump, who plans to withdraw America from the Paris deal, has not read it. 计划让美国退出巴黎协议的唐纳德?特朗普没有读到这份协议。

A mix of alarm and apathy has both galvanised efforts to secure a 2°C future, and also bedevilled them. 警醒和冷漠的混杂态度鼓励了未来升温控制在2°C的目标设立，也阻碍着这个目标的实现。

A target of 1.5°C is no more likely to be met, but may nonetheless encourage the world to try harder. 尽管1.5°C的目标更难实现，但是可以鼓励世界各国朝此方向做出更多努力。