1.5万名科学家对人类发出“第二次警告”

先说好消息。25年前1700名顶尖科学家大声疾呼，说人类正在让地球越过支撑现有生命的极限。而今，我们已经设法稳定住了让他们担心的臭氧层消失问题。非常棒！

坏消息是，1992年他们告诫我们的其他问题都在不断恶化。因此，现在有几乎是上次人数10倍的科学家，确切地说是15364人，共同向我们发出了“第二次警告”。这是历史上联合署名科学家最多的一篇新闻刊物文章，其中包括动物学家珍•古道尔和博物学家E·O·威尔森，而且看到他们的告诫后，没有理由还会感觉良好。

总的来说，让专家们倍感担忧的是两大趋势。一是气候变化——我们燃烧化石燃料，砍伐森林以及我们的农业作业方式（特别是肉类畜牧养殖）所释放的温室气体让这个问题变得更加严重。二是正在发生的大规模灭绝事件，它威胁着许多我们习以为常的生命形式。

这些科学家本周一指出，其根本原因在于人类数量太多以及我们的消费脱离了控制：

“人类并未采取急需的措施来保护陷入危机的生物圈，他们没能有效限制人口增长，没能对植根于增长的经济所扮演的角色进行再评估，没能减少温室气体排放，没能鼓励使用可再生能源，没能保护生物栖息地、恢复生态系统，也没能治理污染、终止物种毁灭并控制外来物种入侵。”

不过，庆幸的是：我们已经淘汰了破坏臭氧层的化学品（含氯氟烃），从而终结了造成臭氧层空洞的行为，这使臭氧层空洞不断缩小，进而避免了皮肤癌患者比现在多数百万人的局面。

这些科学家写道：“臭氧破坏物质在全球范围内迅速减少，这表明只要果断行动，我们就可以做出积极的改变。我们还在消灭极端贫困和饥饿方面取得了进展”，此外，通过改善女童和女性的教育状况，在降低人口出生率方面也有进步。

科学家们成立了名为“世界科学家联盟”的组织，他们认为，现在我们的决策者需要大力推进其他方面的工作。作为消费者和公民，我们也要这样做。

他们提出了许多建议，让我们从可以令人铭记于心的那些开始：

1. 生育

我们不能再要那么多孩子了。理想情况是把出生人口控制在“最多和死亡人口相当的水平”。也就是说，平均要一个或两个孩子。

2. 饮食和食物浪费

考虑到食品生产对环境的影响，我们可不能再浪费那么多食物了。由于对环境的最严重破坏来自牛羊等人类养殖的反刍动物，这些科学家们建议转向“主要以植物为基础的食品”。

3. 绿色购物

我们需要更注意我们购买和投资的东西，以确保它们“鼓励积极的环境变化”。

4. 了解自然

住在城市中的人越来越多，所以需要重新和自然建立一定的联系。专家们建议“增加孩子们的户外自然教育，并提高社会在了解自然方面的整体参与度”。

以下是他们对决策者的建议：

5. 有环境意识的经济体

我们需要调整经济，“以缩小贫富差距并确保价格、税收和激励制度都考虑到消费模式施加于环境的真实成本”。这些科学家还说：“我们的日常生活行为以及我们的政府部门必须有这样的意识：囊括所有生命的地球是我们唯一的家。”

6. 增加自然保护区

我们需要建立数量远多于现在而且“资金充足、管理完善”的保护区，以保护海洋、淡水、天空和陆地物种。

7. 停止毁灭生态系统

我们不能继续侵占森林、草地以及其他原生动植物栖息地，并且需要恢复已经被砍伐的植物群落，“特别是森林”。可别忘了，森林不光是许多物种不可或缺的家园，它还能吸收温室气体。另外，我们还需要让一些地区恢复野生状态。

8. 停止动物物种毁灭

地球上正在发生第六次大规模灭绝。要制止这场灭绝，我们就得和偷猎以及“威胁物种的开发和贸易”作斗争。

9. 绿色科技

需要停止补贴那些基于化石燃料的能源生产，还需要大量投资于可再生能源并加以使用。

本次警告的一大显著特点是它没有描绘如果人们不改弦易辙而将出现的凄惨局面。

本周一发表的另一篇文章提出了一种衡量全球变暖的方法，几位作者表示这比我们目前使用的方法更准确。但他们指出，现有评估方法看来一直低估了全球变暖的水平，这就造成实现《巴黎气候协定》目标的时间不像此前我们所想的那么多。

来自全世界的领导人目前正在德国波恩参加联合国气候变化大会。美国没有派出官方代表，但确实派人参加了一个并行会议——这一会议把推广“清洁煤炭”作为减少碳排放的一个途径，因而遭到了嘲笑。（财富中文网）

译者：Charlie

审校：夏林

First, the good news. Since 1,700 top scientists issued a dramatic warning 25 years ago about humanity pushing the Earth beyond its capacity to sustain life as we know it, we’ve managed to stabilize one of the things that was worrying them: the depletion of the ozone layer. Yay us!

Unfortunately, everything else they were warning about has only got worse since 1992. So now almost ten times as many scientists—15,364 to be precise—have come together to give us a “second notice.” With signatories including the likes of Jane Goodall and E.O. Wilson, this is the most scientists to ever co-sign a published journal article. And there’s no reason to feel good about what they’re telling us.

Broadly speaking, there are two big trends that are freaking out the experts. The first is climate change, exacerbated by the greenhouse gases we encourage by burning fossil fuels, cutting down forests, and farming the way we do (particularly for meat production). The second is the mass extinction event that is taking place, threatening many life forms that we take for granted today.

The root cause, the scientists said on Monday, is that there are too many of us, and our consumption is out of control:

“By failing to adequately limit population growth, reassess the role of an economy rooted in growth, reduce greenhouse gases, incentivize renewable energy, protect habitat, restore ecosystems, curb pollution, halt defaunation, and constrain invasive alien species, humanity is not taking the urgent steps needed to safeguard our imperiled biosphere.”

But let’s go back to the good news. We managed to stop putting a hole in the ozone layer by phasing out the chemicals that were causing it (cholofluorocarbons) and, as a result, the hole is closing and there are millions fewer cases of skin cancer than there would otherwise have been.

“The rapid global decline in ozone-depleting substances shows that we can make positive change when we act decisively. We have also made advancements in reducing extreme poverty and hunger,” the scientists wrote, adding that we’ve made progress in lowering fertility rates too—largely by improving girls’ and women’s education.

Now, according to the scientists, which have formed a group called the Alliance of World Scientists, our policy-makers need to push hard on other fronts. And so do we, as consumers and citizens.

Their list of recommendations is extensive. Let’s start with those that we as individuals can take to heart:

1. Fertility

We need to stop having so many kids, ideally limiting our reproduction to “replacement level at most.” That means one or two children, on average.

2. Diet and food waste

We need to stop wasting so much food, given the environmental impacts of food production. As the worst environmental impacts come from farming ruminants such as cattle and sheep, the scientists also recommend a shift towards “mostly plant-based foods.”

3. Buy green

We need to pay more attention to the things we buy and invest in, to make sure that they “encourage positive environmental change.”

4. Nature appreciation

People are increasingly living in cities, so they need to retain some connection with nature. The experts recommend “increasing outdoor nature education for children, as well as the overall engagement of society in the appreciation of nature.”

And here are the recommendations for policy-makers:

5. Environmentally aware economies

We need to revise our economies “to reduce wealth inequality and ensure that prices, taxation, and incentive systems take into account the real costs which consumption patterns impose on our environment,” the scientists said, adding: “We must recognize, in our day-to-day lives and in our governing institutions, that Earth with all its life is our only home.”

6. More nature reserves

We need to establish a lot more “well-funded and well-managed” reserves to protect species in the sea and fresh water, in the air and on land.

7. Stop wiping out ecosystems

We need to stop converting forests, grasslands and other native habitats, and we need to restore plant communities that have already been slashed, “particularly forest landscapes.” Forests, lest we forget, aren’t just essential homes to many species; they also absorb greenhouse gases. Also, we need to re-wild certain areas.

8. Stop wiping out animal species

We’re undergoing the sixth mass extinction event in Earth’s history. To fight it, we need to fight poaching and the “exploitation and trade of threatened species.”

9. Green technologies

Fossil fuel-based energy production needs to stop getting subsidized, and we need massive investment in and adoption of renewable energy sources.

One notable aspect of the letter was the fact that it avoided spelling out the doomier scenarios that we face if we don’t change tack.

A separate paper published on Monday proposed what the authors said was a more accurate way of measuring global warming than those we currently use. And unfortunately, they said, it looks like our existing estimates have been underplaying how much warming is currently taking place, leaving us less time than we thought to achieve the targets set out in the Paris Climate Agreement.

Policy-makers from around the world are currently meeting in Bonn, Germany, under the auspices of the United Nations Climate Change Conference (COP 23). The U.S. did not send a formal delegation, but it did send delegates to a side event where they were derided for promoting “clean coal” as a way to reduce carbon emissions.