It’s April 10th, 1815, and in just a few moments, the sun is going to disappear. On an island in present-day Indonesia, Mount Tambora erupts with a boom that can be heard over 2,000 kilometers away. Sulfurous plumes of steam and ash billow thousands of meters into the sky, forming dark storm clouds of soot and lightning. This eruption will go down as the largest in recorded history, but, at this point, its impact is only just beginning. Ascending high into the atmosphere, Tambora’s emissions spread across the globe, blotting out the sun for almost an entire year. The hazy skies and cold weather of 1816 wreak havoc on agriculture, leading to famines all across the Northern Hemisphere. Nations struggle with epidemics, and artists craft bleak tributes to these seemingly apocalyptic times. This was the year without summer— literally one of the darkest periods in human history. So why are some modern researchers looking for ways to repeat it?
此刻是 1815 年四月十日, 再過一會兒 太陽就會消失。 在現今屬於印尼的一座島嶼上, 坦博拉火山砰一聲爆發了, 兩千公里外都能聽到這聲巨響。 熱氣和火山灰構成的硫磺熱柱 翻騰數千公尺直達天際, 形成黑暗的暴風雲, 充滿煤灰和閃電。 這次的噴發,是歷史 記錄上最大的一次, 但在此刻,它的衝擊 影響才剛剛開始。 衝升至大氣高空之後, 坦博拉火山的排放物散播至全球, 遮蔽了陽光將近一整年。 1816 年的朦朧天空和寒冷天氣 重創了農業, 造成北半球各地的飢荒。 國家為疫情所苦, 藝術家創作出悲傷的作品, 向這看似末日般的時代致意。 這是沒有夏天的那一年—— 真可說是人類歷史上 最黑暗的時期之一。 那為什麼有些現代的研究者 在想辦法讓它再次發生?
Obviously, no one wants to replicate this period’s famine and despair. But some scientists are interested in using sulfurous haze to block out the sun, and hopefully, slow the effects of global warming. This is one of many proposals in the realm of geoengineering— a class of deliberate, large-scale interventions in Earth’s natural systems intended to help restrain climate change. Different geoengineering schemes intervene in different systems. Any plans to cool the planet by blocking the amount of sunlight reaching the earth would fall in the category of solar radiation management. Some of these proposals are massive in scale, such as suggestions to create a helpful version of volcanic plumes or build a giant sunshade in Earth’s orbit. Others are more limited, focusing on enhancing natural cooling systems. For example, researchers might enlarge marine clouds or make Earth reflect more sunlight by building huge swaths of white surfaces.
很顯然,沒有人會想要重現 這段時期的饑荒和絕望。 但讓一些科學家感興趣的 是用硫磺霧靄來阻擋太陽光, 希望能讓全球暖化的效應緩下來。 這是地球工程學領域中的 眾多提案之一—— 這個領域在做的是: 刻意用大規模的方式干預 地球的自然系統, 旨在協助遏制氣候變遷。 不同的地球工程方案 干預不同的系統, 凡是打算用阻擋部分陽光照射到 地球的方式來讓地球冷卻的計畫 都列為太陽輻射管理的類別。 這類提案當中,有些的規模相當大, 比如建議創造出有助益的火山熱柱, 或者在地球的軌道上 建造巨型遮陽板。 其他提案則比較有限, 把焦點放在強化大自然的冷卻系統。 比如,研究者可能會擴大海洋雲層, 或者讓地球反射更多陽光, 用建造大片白色表面的方式來達成。
Many of these plans sound more than a little strange. But there’s reason to believe they might work, not least because of natural events like the eruption of Tambora. Scientists know that volcanic eruptions have periodically cooled the climate. Both the Pinatubo eruption in 1991 and 1883′s blast of Krakatoa reduced global average temperatures by at least half-a-degree Celsius for up to a year. These cooling effects are global and fast acting— but they're also incredibly risky. The Earth is a chaotic system where even the smallest changes can create countless unpredictable ripple effects. We know that cooling temperatures impacts precipitation, extreme weather, and other climate phenomena, but it’s difficult for even the most advanced computer models to predict how or where these consequences will occur. One country’s solar radiation management might be another country’s unnatural disaster, causing extreme weather or crop failures like those following Tambora’s eruption. And even if these schemes did safely cool the planet, solar radiation management doesn’t address the greenhouse gases that are causing global warming. These solutions are just highly experimental band-aids that the world would have to endure for at least a few decades while we work on actually removing CO2 from the air. And if we pulled that band-aid off prematurely, global temperatures could rapidly rebound, causing a period of intense super warming.
這些計畫有不少聽起來都挺奇怪的。 但有理由相信它們可能可行, 尤其是因為有像坦博拉爆發 這樣的事件發生。 科學家知道,火山爆發 會定期讓氣候冷卻下來。 1991 年的皮納圖博火山爆發 以及 1883 年的喀拉喀托火山爆發 都讓全球平均溫度下降了 至少攝氏半度,且時間長達一年。 這些冷卻效應是全球性的, 且作用迅速, 但風險也相當高。 地球是個很混亂的系統, 即使是最小的改變 都可能造成相當多 無法預測的漣漪效應。 我們知道冷卻溫度會影響水氣凝結、 極端天氣,以及其他氣候現象, 但即使用最先進的電腦模型也很難 預測這類後果會發生在 何處、如何發生。 一個國家的太陽輻射管理 可能是另一個國家的非天然災害, 造成極端天氣或者作物歉收, 如坦博拉火山爆發之後 發生的那些現象。 就算這些方案真的 安全地讓地球冷卻下來, 太陽輻射管理並沒有處理掉 造成全球暖化的溫室氣體。 這些解決方案只是高度實驗性的 OK 繃(權宜之計), 世界還得忍受它們至少幾十年, 等真正能夠將空氣中 二氧化碳除去的方法問世。 如果我們太早將那些 OK 繃撕掉, 全球氣溫可能會快速回彈, 引發一段劇烈升溫的時期。
For these reasons and more solar radiation management is risky. Today, researchers are running small-scale experiments, such as enhancing marine clouds to protect the Great Barrier Reef from further heating and bleaching. And most scientists agree that we should pursue ways to cut emissions and remove atmospheric CO2 first and foremost. However, there are reasons to keep studying these more aggressive approaches. Desperate times call for desperate measures, and in the future, geoengineering might be civilization’s last resort. Furthermore, some of these plans would be shockingly easy to execute by some rogue actor with enough cash. So we’ll want to be prepared if someone starts geoengineering without governmental approval. But perhaps the most important reason to investigate the impacts of geoengineering is that people are already making large scale interventions in the atmosphere. In many ways, climate change is an unintended geoengineering project fueled by the emissions generated from centuries of burning fossil fuels. And unless we take action to curb emissions and draw CO2 out of the atmosphere soon, summer may never be the same again.
基於這些理由和其他原因, 太陽輻射管理的風險很高。 現今的研究者在做小規模的實驗, 比如強化海洋雲層來保護大堡礁 避免更進一步的升溫和白化。 大部分的科學家同意, 想辦法減少排放 以及除去大氣中的二氧化碳 是我們首要的任務。 然而,要繼續研究這些比較 激進的方法也是有原因的。 在絕望的時刻需要用上絕望的措施, 而在未來, 地球工程學可能會是 文明的最後手段。 此外,這些計畫當中, 有些非常容易執行, 有足夠現金的流氓行動就辦得到。 如果有人未獲得政府批准 就進行地球工程, 我們會希望能做好準備。 但,也許研究地球工程 會造成什麼衝擊的最重要理由 是人已經大規模地干預大氣了。 在許多方面, 氣候變遷就像是個非蓄意 啟動的地球工程計畫, 由數世紀燃燒化石燃料 所產生的排放物所推動。 除非我們採取行動來抑制排放, 並盡快將二氧化碳從大氣中除去, 不然,夏天將永遠 不會跟以前一樣了。