對氣候變化的無所作為風險留下未來幾代人的債務為530萬億美元
藝術學分: 碳視覺 (CC by 2.0)

By continuing to delay significant reductions in greenhouse gas emissions, we risk handing young people alive today a bill of up to US$535 trillion. This would be the cost of the “negative emissions” technologies required to remove CO? from the air in order to avoid dangerous climate change.

這些是新研究的主要發現 地球系統動力學由美國氣候科學家詹姆斯·漢森(James Hansen)領導的一個國際小組進行,他曾擔任美國宇航局戈達德空間研究所所長。

巴黎協定 in 2015 saw the international community agree to limit warming to within 2°C. The Hansen team argue that the much safer approach is to reduce atmospheric concentrations of CO? from the current annual average of more than 400ppm (parts per million) back to 1980s levels of 350ppm. This is a moderately more ambitious goal than the aspiration announced in Paris to further attempt to limit warming to no more than 1.5°C. Many climate scientists and policymakers believe that either the 2°C or 1.5°C limits will 只有負排放才有可能 因為國際社會將無法及時減少所需的時間。

將碳放回地下

最有希望的負排放技術是BECCS-- 具有碳捕獲和封存的生物能源. It involves growing crops which are then burnt in power stations to generate electricity. The carbon dioxide produced is captured from the power station chimneys, compressed, and piped deep down into the Earth’s crust where it will be stored for many thousands of years. This scheme would allow us to both generate electricity and reduce the amount of CO? in the Earth’s atmosphere.

碳
其他能源充其量只是碳中性,但BECCS的排放量超過排放量。 Elrapto, CC BY-SA


內在自我訂閱圖形


BECCS有 重要的限制,例如滿足我們的能源需求所需的大量土地,水和肥料。 也許更重要的是,它不存在於它所需的規模之類的任何東西。 到目前為止只有很小 試點項目 已證明其可行性。 其他負面排放方法 涉及 給海洋施肥 增加光合作用,或 直接空中捕獲 which sucks CO? out of the air and converts it into plastics or other products.

The Hansen team estimate how much it will cost to extract excess CO? with BECCS. They conclude that it would be possible to move back to 350ppm mainly with reforestation and improving soils, leaving around 50 billion tonnes of CO? to be mopped up with negative emissions technologies (the plants grown for BECCS take in the CO?, which is then sequestered when burned).

But that’s only if we make significant reductions in rates of emissions right now. If we delay, then future generations would need to extract over ten times more CO? beyond the end of this century.

They estimate costs between US$150-350 for each tonne of carbon removed via negative emissions technologies. If global emissions are reduced by 6% each year – a very challenging but not impossible scenario – then bringing CO? concentrations back to 350ppm would cost US$8-18.5 trillion, spread over 80 years at US$100-230 billion a year.

如果排放量持平或每年增加2%,則總成本至少達到89萬億美元,可能高達535萬億美元。 八十年來每年的1.1到6.7萬億美元。

為了給這些數字一些背景, 整個美國聯邦預算 大約是4萬億美元,而所有國家的年度支出都在 軍事和國防 是1.7萬億美元。

氣候平衡法案

人類已經抽筋了 1.5萬億噸 of CO? into the atmosphere since 1750. It is not just the amount, but the rate at which this CO? has been added. The oceans can absorb extra CO? but not fast enough to remove all human inputs and so it has been 逐步建立起來的氛圍. This extra CO? traps more heat than would otherwise escape out into space. More energy is therefore entering the climate system than leaving it.

幾十年和幾個世紀以來,氣候將與進入的相同數量的能量重新平衡。 但這將是一個更高的溫度,其中包括更少的冰,更高的海平面,更多的熱浪和更多的洪水。 上一次地球氣候經歷了這種能量不平衡的原因是 Eemian間冰期 一些115,000多年前。 那時全球海平面比今天高出六到九米。

漢森團隊認為,即使保持目前的能源不平衡,也有可能鎖定幾米的海平面上升。 這是因為諸如融化冰蓋之類的緩慢過程仍然沒有“趕上”。 氣候失衡的時間越長,其影響就越大。

反對大幅削減溫室氣體排放的一個論點是,它將損害經濟,因為我們的產業仍然主要是化石燃料。 應對氣候變化需要平衡今天繼續發展經濟的願望,避免災難性的氣候變化或明天過於昂貴的補救措施。

無論您對經濟增長做出何種假設,或者無論您對未來成本的折扣多少,都難以想像可以獲得535萬億美元。 雖然這些費用將分散在80年,但也將是全球人口將從70億增加到可能的時期 11十億甚至更多. Humanity will need to grow enough crops to feed these billions while fuelling BECCS schemes at a time when climate change will already be impacting food production. There are also no guarantees that BECCS or any other negative emission technologies will actually work. If they fail then large amounts of CO? could be released very rapidly with disastrous consequences.

談話通過推遲大幅減少碳排放,我們有可能將不可能的財政和技術負擔交給後代。 我們的子孫可能無法理解我們如何代表他們談判這樣的安排。

關於作者

James Dyke,可持續發展科學講師, 英國南安普敦大學

這篇文章最初發表於 談話。 閱讀 原創文章.

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