紐時賞析／復育森林有助減緩氣候變遷 但仍不夠

Climate Study Shows Restoration of Forests Isn’t Enough by Itself

森林對於因應氣候變遷很有幫助 但還不夠

Restoring global forests where they occur naturally could potentially capture an additional 226 gigatons of planet-warming carbon, equivalent to about one-third of the amount that humans have released since the beginning of the Industrial Era, according to a new study published in the journal Nature.

發表在「自然」期刊的新研究指出，復育全球自然森林可額外捕獲226十億噸造成全球暖化的碳，相當於工業化時代以來人類排碳量的三分之一。

The research, with input from more than 200 authors, leveraged vast troves of data collected by satellites and on the ground and was partly an effort to address the controversy surrounding an earlier paper. That study, in 2019, helped to spur the Trillion Trees movement but also caused a scientific uproar.

這份研究由超過200名作者投入，利用大量衛星和地面收集數據，部分是為了處理關於一份早期論文的爭議。那份2019年的研究協助推動了「兆樹計畫」，但也引起科學界議論。

The new conclusions were similar to those in a separate study published last year. Mainly, the extra storage capacity would come from allowing existing forests to recover to maturity.

新結論和去年發表的另一項研究類似。主要是額外的碳儲存容量源自將現有森林復育至完善。

The 226 gigatons of storage cannot be achieved without cutting greenhouse gas emissions, said Thomas Crowther, the study’s senior author and a professor of ecology at ETH Zurich, a university in Switzerland. “If we continue emitting carbon, as we’ve done to date, then droughts and fires and other extreme events will continue to threaten the scale of the global forest system, further limiting its potential to contribute.”

該研究資深作者、瑞士蘇黎世聯邦理工學院生態學教授克勞瑟表示，如果不減少溫室氣體排放，就無法達成226十億噸的存量。他說：「如果像我們至今為止所做的那樣繼續排碳，那麼乾旱、野火和其他極端事件將持續威脅全球森林系統，進一步限制其貢獻潛力。」

Forests are essential to tackling both the climate and biodiversity crises. And they pull climate-warming carbon out of the atmosphere.

森林對於應對氣候和生物多樣性危機至關重要。它們也從大氣吸收導致氣候暖化的碳。

Crowther was the senior author of a polarizing study on forest carbon in 2019 that drew scientific backlash but also inspired an effort by the World Economic Forum to grow and conserve 1 trillion trees.

克勞瑟是2019年引發兩極反應的森林碳研究資深作者。這份研究引起科學界強烈反彈，也激發世界經濟論壇努力種植和保護1兆棵樹。

In 2019, he acknowledged, careless language led to trees being wrongly painted as a silver bullet for climate change. Now, his biggest fear is that countries and companies will keep treating forests that way, using them for carbon offsets to enable the continued use of fossil fuels.

他承認，在2019年，粗心的語言導致樹木被錯誤地描繪成解決氣候變遷的良方。現在，他最怕的是國家和企業繼續以這種認知對待森林，利用它們抵銷排碳量，以繼續使用化石燃料。

His new study’s number of 226 gigatons of carbon approximates his previous one of 205, but it gets there differently. Both papers exclude urban areas, croplands and pastures but include rangelands, where animals may graze at lower densities. In the new research, 61% of the additional carbon storage would come from protecting existing forests and the other 39% from growing trees in deforested areas with low human footprints.

他的新研究所得出的226十億噸碳的數據，和先前的205十億噸近乎相同，但得出結果的方式截然不同。兩份論文都排除城市地區、農田和牧場，但包括牧地，那裡的動物吃草密集度較低。在新研究中，61%的額外碳存量來自保護現有森林，39%來自在低度人類足跡的森林砍伐區種樹。

In the 2019 study, all the carbon came from growing trees where they could occur naturally outside of existing forests. More than 50 scientists published seven critiques in Science that year, disputing both the analysis and its implications.

在2019年研究中，所有的碳都來自正在生長的樹木，能在現有森林外自然產生。當年超過50名科學家在「科學」期刊發表七篇評論，質疑這項研究的分析以及其含義。

文／Catrin Einhorn 譯／羅方妤

說文解字看新聞

【羅方妤】

COP28在杜拜盛大登場，會前傳出的消息卻不容樂觀。發表在「自然」期刊的研究指出，復育全球自然森林可額外捕獲226十億噸造成全球暖化的碳，相當於工業化時代以來碳排放量的三分之一。然而，科學家指出，人類如果持續像以往一樣排碳，乾旱和野火等極端天氣事件會威脅森林，限制其作用。

這篇研究是為了解決2019年研究引發的部分爭議。儘管當年研究推動了「兆樹計畫」，但當年研究資深作者、瑞士蘇黎世聯邦理工學院生態學教授克勞瑟也承認，樹木被錯誤描繪成解決氣候變遷的良方。他擔心國家和企業利用森林抵銷碳排放量，又繼續使用化石燃料。

Trillion Trees movement是指世界經濟論壇2020年發起的「兆樹計畫」，目標聯合政府、非政府組織、企業和個人在地球種植、復育和保留一兆棵樹。

文中gigaton是指十億噸（Gt），是常用於計算氣體量的單位。研究論文的資深作者（senior author）與第一作者（first author）不同。