到2070年，世界上1/3的人口将会笼罩在撒哈拉般的热浪中

A Third of the World's Population Could Be Blanketed in Sahara-Like Heat by 2070

到2070年，世界上三分之一的人口将会笼罩在撒哈拉般的热浪中

Brain geniuses like Elon Musk may want to colonize Mars, which sure. But for simpletons like me, keeping Earth mostly habitable seems like a better use of time and resources.

像埃隆·马斯克这样的大脑天才可能想要征服火星，好吧，这是肯定的。但是对于像我这样的傻瓜来说，让地球的大部分都适合人类居住似乎是对时间和资源的更好利用。

If carbon emissions are allowed to continue unchecked, though, that may be a tough proposition. According to a new study, extreme heat now only found in parts of the Sahara could spread to nearly 20 percent of the globe (and nearly a third of humanity) if carbon emissions aren’t curtailed. The paper, published on Monday in the Proceedings of the National Academy of Sciences, makes a pretty compelling case to cut carbon emissions and not fry the world.

然而，如果碳排放继续不受限制，这可能是一个艰难的事情。根据一项新研究，如果不减少碳排放，目前只在撒哈拉沙漠部分地区发现的极端高温可能会蔓延到全球近20%的地区（波及近三分之一的人类）。这篇周一发表在《美国国家科学院院刊》上的论文为减少碳排放，不让全球变暖提出了一个相当有说服力的理由。

The authors of the new paper use a host of historical data going back 6,000 years ago to uncover just what conditions make humans tick. It turns out people can make do with all levels of rainfall, with humans living in all but the very driest places on Earth. Civilization has also adapted to all types of soil fertility. The biggest limiting factor in terms of human habitation is how hot it gets.

这篇新论文的作者使用了近6000年的大量历史数据来揭示人类生存的条件。事实证明，除了在地球上最干旱的地方，人类都可以设法应对各种程度的降雨。文明也适应了各种类型的土壤肥力。人类居住的最大限制因素是温度会有多高。

The results of the study show people thrive in a narrow temperature band, where the average annual temperature spans 11 to 15 degrees Celsius or roughly the 50s if you’re into Fahrenheit. It’s in that belt where many staple crops grow best and livestock can be highly productive, and it’s why the authors define it as the “human climate niche.” That’s not say there aren’t other confounding factors for human thriving, but temperature is one of the key elements linked with well-being.

研究结果显示，人们只能在一个狭窄的温度范围内生活得很好，这一范围是年平均温度在11到15摄氏度之间，如果你喜欢华氏温度，那大概就在50多华氏度左右。正是在这一范围内，许多主食作物长势最好，牲畜产量也很高，这也就是作者将其定义为“人类气候生态位”的原因。这并不是说没有其他影响人类健康的因素，但温度是影响健康的关键因素之一。

Unfortunately for us, there’s a shock on the way if climate change continues unchecked. We’re already seeing the toll rising heat is taking on people around the world, from heat wave-related deaths to billions of hours in lost productivity because it was simply too hot to be outside. Still, humans have made it work in many hot places, from Phoenix to New Delhi to Dubai. But eventually, climate change could overwhelm us.

对我们来说不幸的是，如果气候变化继续不受控制，我们就会面临冲击。我们已经看到了不断上升的高温对世界各地的人们造成的影响，从热浪导致的死亡，到因天气太热而无法外出导致的数十亿小时的生产力损失。尽管如此，从凤凰城到新德里再到迪拜，人类已经在许多炎热的地方想办法克服高温。但最终，气候变化会压倒我们。

The study uses RCP8.5, a scenario where carbon emissions rise on an extreme level, to model what the end of the century would look like for our little human climate niche. The results show it would contract substantially. The Sahara is one of the only places on Earth where the annual average temperature cranks above 29 degrees Celsius (84 degrees Fahrenheit) and where the human climate niche basically ends. The areas with that much heat only cover 0.8 percent of the world’s land. But by 2070, that type of heat would become commonplace over nearly 20 percent of land on Earth. That area is home to up to 3 billion people who, if they don’t migrate, will be living in conditions humans have never been able to tolerate for year-round existence.

该研究使用了RCP8.5，即碳排放达到极端水平的情景，来模拟本世纪末人类气候生态位的状况。结果表明，它将大幅缩小。撒哈拉沙漠是地球上仅有的年平均气温超过29摄氏度（84华氏度）的地方之一，也是人类气候生态位基本结束的地方。拥有如此高热量的地区仅占世界陆地面积的0.8%。但到2070年，这种类型的高温将在地球近20%的土地上变得司空见惯。这么大的地区是多达30亿人的家园，如果他们不迁移，将会生活在人类永远无法忍受的环境中。

What’s more, this spike in temperature over the intervening 50 years will be more dramatic than anything experienced in at least 6,000 years. You know, the period where human civilization really hit its groove.

更重要的是，这50年间的温度峰值将比至少6000年来的任何一次都要剧烈。你要知道，这段时间也是人类文明真正达到巅峰的时期。

The results are truly shocking in map form. Nearly all of Brazil will become essentially uninhabitable, as will huge chunks of the Middle East and India, showing the poorest areas will be hit the hardest. But the impacts aren’t limited to developing countries; the U.S. South, parts of Australia, and Mediterranean Europe will also see temperatures beyond the niche. The flip, though, that North America and Europe will also make habitability gains. When scientists found last year that we were all going to want to move to Siberia by the end of the century, they weren’t kidding.

以地图形式呈现的结果确实令人震惊。几乎整个巴西都将变得无法居住，中东和印度的大部分地区也将如此，这表明最贫困的地区将受到最严重的打击。但影响并不仅限于发展中国家；美国南部、澳大利亚部分地区和欧洲地中海地区的气温也将超过生态位的范围。不过，反过来说，北美和欧洲的居住性会有所提高。当科学家们去年发现我们都会在本世纪末搬到西伯利亚时，他们并不是在开玩笑。

That’s what’s most alarming about the results. They show that, absent curbing emissions, there will almost certainly be mass migrations out of the hot zones. It won’t all happen in 2070 like a switch flipped. Rather, some areas will pass the climate niche threshold first, potentially triggering waves of migration. The results show that, first and foremost, we need to start cutting emissions now. But just as important is the need to prepare for climate-induced migration in the future. And not in the ecofascist kind of way.

这就是最令人担忧的结果。它们表明，如果不遏制排放，几乎可以肯定会有大量人口迁出高温地区。这一切并不会像开关一样在2070年开启。相反，一些地区将首先突破气候生态位阈值，可能引发移民潮。研究结果表明，首先，我们需要现在就开始减少碳排放。但同样重要的是，需要为未来因气候导致的移民做好准备，而不是用生态法西斯的方式应对它。