Does planting trees actually cool the planet? - Carolyn Beans

翻译人员: Gia Hwang 校对人员: Yip Yan Yeung

In the fight to curb climate change,

在遏制气候变化的斗争中，

there are few solutions more discussed than planting lots and lots of trees.

讨论最多的方案莫过于大量植树。

It sounds simple enough— trees absorb CO2 from the atmosphere to grow,

听起来很简单：树木生长 会吸收大气中的二氧化碳，

so planting more of them should help eliminate greenhouse gases.

因此，种植更多树木 应该有助于消除温室气体。

The trouble is, tree planting efforts don't always work as planned.

问题是植树工作并非总按计划进行。

For example, between 1974 and 2012,

例如，在 1974 年至 2012 年间，

the Chilean government helped fund the planting

智利政府资助种植了

of over a million hectares of new trees.

超过一百万公顷的新树。

Yet a recent analysis suggests this multi-million dollar effort

然而，最近的一项分析表明， 这项数百万美元的努力

resulted in no major carbon storage gains.

并未带来重大的碳储量收益。

What went wrong?

出了什么问题？

Chile focused on afforestation:

智利侧重于植树造林，

the planting of trees in places long devoid of— or never home to— any forest,

即在长期没有 或从未有森林的地方植树，

as opposed to reforestation,

而不是森林恢复，

the practice of restoring recently degraded forests.

即恢复最近退化的森林的做法。

Many governments and international organizations champion afforestation

许多政府和国际组织倡导植树造林，

in their efforts to meet lofty tree planting goals

努力实现崇高植树目标，

that require massive amounts of land.

此举需要大量土地。

The Bonn Challenge, launched in 2011 by the German government

德国政府和国际自然保护联盟

and the International Union for Conservation of Nature,

于 2011 年发起了波恩挑战，

aims to restore 350 million hectares of degraded land

旨在到 2030 年

across the globe by 2030,

恢复全球 3.5 亿公顷的退化土地，

in part through afforestation.

部分方法就是植树造林。

Many companies have also seized on tree planting to offset emissions

许多公司还利用植树来抵消排放，

and, in some cases, negative PR from their contributions to the climate emergency.

而且某些情况下，还用对气候 紧急情况的贡献来抵消负面公关。

A 2021 Oxfam analysis found that the area needed to match the tree planting goals

乐施会 2021 年的一项分析发现，

set by four of the largest oil and gas producers

要实现四家最大的石油 和天然气生产商设定的植树目标，

would require land twice the size of the UK.

所需土地将是英国面积的两倍。

Here's where things get complicated.

这是事情变得复杂的地方。

In order to be a long-term carbon sink,

树木要成为长期碳汇，

trees need to grow to maturity and stay put.

需要长大成才并留在原地。

Most of Chile's afforestation funding went to the commercial forestry industry,

智利的大部分造林资金 都流向了商业林业，

which drastically expanded plantations of mostly non-native trees—

大幅扩大种植主要是非本地树木——

in some cases even by plowing into native forests.

某些情况下，甚至毁坏原始林去种植。

According to one study, on average,

根据一项研究，平均而言，

natural forests are 40 times better at carbon storage than plantations.

天然林的碳储量是人工林的 40 倍。

A mature tree can absorb up to 22 kilograms of carbon dioxide each year.

一棵成年树每年可吸收 多达 22 千克二氧化碳，

But plantation trees are harvested.

但是种植树成才会砍伐。

Further, pine and eucalyptus— two commonly grown plantation trees—

此外，松树和桉树—— 两种常见的种植树——

are highly flammable,

非常易燃，

so gains in carbon storage can quickly go up in smoke.

因此碳储存的增加很快会化为乌有。

And not all land should be forested.

而且，并非所有土地都应该是森林。

In 2019, researchers estimated that, of the 100 million hectares of land

2019 年，研究人员估计，

在非洲植树计划的一亿公顷土地中，

targeted for a tree planting initiative in Africa,

most is savanna.

大部分是稀树草原。

Dropping trees into Africa’s savannas threatens wildlife

向非洲稀树草原投放树木，

会危及在阳光和空地上 茁壮成长的野生动物。

that thrive in sunlight and open spaces.

And wildfires, not to mention a passing elephant,

而且，不用说途经的大象了，

can quickly stomp out years of tree growth.

野火可以迅速摧毁多年生长的树木。

Meanwhile, a savanna’s natural vegetation tucks most of its carbon

同时，稀树草原的自然植被

将其大部分碳安全地藏在地下，

safely away below ground,

where it’s protected from fire and hungry herbivores.

保护它免受火灾 和饥饿食草动物的侵害。

Planting trees can also have unintended consequences

在自然反射阳光的地方，

in places that naturally reflect sunlight

例如旱地或白雪皑皑的地方，

like drylands or snowy terrain.

植树也可能产生意想不到的后果。

Trees in these regions could absorb more of the Sun’s rays,

这些地区的树木会吸收更多阳光，

contributing to a warmer planet.

从而使地球变暖。

It’s not that we shouldn’t plant more trees.

并不是说我们不该种更多的树，

But for the best chance of success,

但是，为了获得最大的成功机会，

programs should consider which species to plant, which lands to forest,

项目应考虑要种哪些品种、 哪些土地可以种植，

and how to protect the land long-term.

以及如何长期保护土地。

Today, Chile is prioritizing planting native trees

如今，智利优先种植本地树木，

rather than timber plantations.

而不是木材种植园。

Some researchers argue that a more efficient way to re-green the planet

一些研究人员认为， 重新绿化地球的更有效方法

is to protect forests and let nature do the work.

是保护森林，让大自然发挥作用。

On recently deforested land,

在最近被砍伐的土地上，

seeds wait in soil and new sprouts grow from old stumps.

种子在土壤中蓄势，老桩长出新芽，

As time passes, birds and winds deliver seeds from forests nearby.

随着时间流逝，鸟类和风 会从附近的森林运来种子。

Others support programs that practice assisted natural regeneration—

其他人则支持开展 辅助自然再生的计划——

helping nature along by removing grasses that compete with saplings,

通过铲除与树苗竞争的草、

preventing grazing, and even planting trees in small patches.

防止放牧、甚至种植小片树 来帮助大自然。

So when is it bad to plant trees?

那什么时候种树不好呢？

When programs put the wrong trees in the wrong places.

当项目将错误的树种到错误地方时。

It’s bad when it’s mistakenly used as a catch-all solution,

如果它被误当作包罗万象的解决方案，

rather than addressing more complex issues like carbon emissions

而不是解决更复杂问题 如碳排放和主动毁林，

and active deforestation.

那就太糟糕了。

It’s also bad to plant trees when it allows companies and governments

当此举允许公司和政府进行漂绿，

to practice greenwashing,

throwing money at initiatives that have no real chance of achieving

将资金投入到

其不可能达标的碳补偿计划时，

the carbon offsets they promise.

植树也是不好的。

The best investments in a greener future are to cut carbon emissions,

对更绿未来的最佳投资 是减少碳排放，

while protecting these forests from being destroyed in the first place.

同时首先保护这些森林免遭破坏。