先說好消息。25年前1700名頂尖科學家大聲疾呼，說人類正在讓地球越過支撐現有生命的極限。而今，我們已經設法穩定住了讓他們擔心的臭氧層消失問題。非常棒！

壞消息是，1992年他們告誡我們的其他問題都在不斷惡化。因此，現在有幾乎是上次人數10倍的科學家，確切地說是15364人，共同向我們發出了“第二次警告”。這是歷史上聯合署名科學家最多的一篇新聞刊物文章，其中包括動物學家珍?古道爾和博物學家E·O·威爾森，而且看到他們的告誡后，沒有理由還會感覺良好。

總的來說，讓專家們倍感擔憂的是兩大趨勢。一是氣候變化——我們燃燒化石燃料，砍伐森林以及我們的農業作業方式（特別是肉類畜牧養殖）所釋放的溫室氣體讓這個問題變得更加嚴重。二是正在發生的大規模滅絕事件，它威脅著許多我們習以為常的生命形式。

這些科學家本周一指出，其根本原因在于人類數量太多以及我們的消費脫離了控制：

“人類并未采取急需的措施來保護陷入危機的生物圈，他們沒能有效限制人口增長，沒能對植根于增長的經濟所扮演的角色進行再評估，沒能減少溫室氣體排放，沒能鼓勵使用可再生能源，沒能保護生物棲息地、恢復生態系統，也沒能治理污染、終止物種毀滅并控制外來物種入侵。”

不過，慶幸的是：我們已經淘汰了破壞臭氧層的化學品（含氯氟烴），從而終結了造成臭氧層空洞的行為，這使臭氧層空洞不斷縮小，進而避免了皮膚癌患者比現在多數百萬人的局面。

這些科學家寫道：“臭氧破壞物質在全球范圍內迅速減少，這表明只要果斷行動，我們就可以做出積極的改變。我們還在消滅極端貧困和饑餓方面取得了進展”，此外，通過改善女童和女性的教育狀況，在降低人口出生率方面也有進步。

科學家們成立了名為“世界科學家聯盟”的組織，他們認為，現在我們的決策者需要大力推進其他方面的工作。作為消費者和公民，我們也要這樣做。

他們提出了許多建議，讓我們從可以令人銘記于心的那些開始：

1. 生育

我們不能再要那么多孩子了。理想情況是把出生人口控制在“最多和死亡人口相當的水平”。也就是說，平均要一個或兩個孩子。

2. 飲食和食物浪費

考慮到食品生產對環境的影響，我們可不能再浪費那么多食物了。由于對環境的最嚴重破壞來自牛羊等人類養殖的反芻動物，這些科學家們建議轉向“主要以植物為基礎的食品”。

3. 綠色購物

我們需要更注意我們購買和投資的東西，以確保它們“鼓勵積極的環境變化”。

4. 了解自然

住在城市中的人越來越多，所以需要重新和自然建立一定的聯系。專家們建議“增加孩子們的戶外自然教育，并提高社會在了解自然方面的整體參與度”。

以下是他們對決策者的建議：

5. 有環境意識的經濟體

我們需要調整經濟，“以縮小貧富差距并確保價格、稅收和激勵制度都考慮到消費模式施加于環境的真實成本”。這些科學家還說：“我們的日常生活行為以及我們的政府部門必須有這樣的意識：囊括所有生命的地球是我們唯一的家。”

6. 增加自然保護區

我們需要建立數量遠多于現在而且“資金充足、管理完善”的保護區，以保護海洋、淡水、天空和陸地物種。

7. 停止毀滅生態系統

我們不能繼續侵占森林、草地以及其他原生動植物棲息地，并且需要恢復已經被砍伐的植物群落，“特別是森林”。可別忘了，森林不光是許多物種不可或缺的家園，它還能吸收溫室氣體。另外，我們還需要讓一些地區恢復野生狀態。

8. 停止動物物種毀滅

地球上正在發生第六次大規模滅絕。要制止這場滅絕，我們就得和偷獵以及“威脅物種的開發和貿易”作斗爭。

9. 綠色科技

需要停止補貼那些基于化石燃料的能源生產，還需要大量投資于可再生能源并加以使用。

本次警告的一大顯著特點是它沒有描繪如果人們不改弦易轍而將出現的凄慘局面。

本周一發表的另一篇文章提出了一種衡量全球變暖的方法，幾位作者表示這比我們目前使用的方法更準確。但他們指出，現有評估方法看來一直低估了全球變暖的水平，這就造成實現《巴黎氣候協定》目標的時間不像此前我們所想的那么多。

來自全世界的領導人目前正在德國波恩參加聯合國氣候變化大會。美國沒有派出官方代表，但確實派人參加了一個并行會議——這一會議把推廣“清潔煤炭”作為減少碳排放的一個途徑，因而遭到了嘲笑。（財富中文網）

譯者：Charlie

審校：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.