(本文选自《经济学人》20210410期)
背景介绍：
近日，来自中国科学院和清华大学的学者在《自然-通讯》杂志上发表了一篇题为《中国比特币区块链运行的碳排放量与可持续性的政策评估》的论文。论文称，在没有任何政策干预的情况下，中国比特币区块链的年能耗预计将在2024年达到峰值296.59太瓦时，产生1.305亿公吨碳排放，将超过捷克和卡塔尔的年度温室气体排放总量。
Totting up bitcoin’s environmental costs
As coinbase’s Ipo shows,
cryptocurrencies
have many fans. But they have detractors, too. Environmentalists, in particular, fret about how much energy bitcoin uses.
正如 Coinbase 首次公开募股所显示的那样，加密货币拥有众多粉丝。但同时也不乏批评者。环保主义者尤其为比特币所的能源消耗量而担忧。
In a paper in Nature Communications, a group of academics led by Dabo Guan of Tsinghua University and Shouyang Wang at the Chinese Academy of Sciences examine bitcoin’s energy use in China.
在发表于《自然-通讯》杂志的一篇论文中，清华大学的关大博和中国科学院的王守阳带领一组学者对比特币在中国的能源消耗情况展开了研究。
They conclude that, in the absence of legal curbs, bitcoin could by 2024 become a “non-negligible” barrier to China’s efforts to decarbonise its economy.
他们得出结论称，在缺乏法律限制的情况下，到2024年，比特币可能会成为中国经济脱碳努力“不可忽视的”障碍。
Bitcoin’s hunger for energy stems from its design. It forgoes centralised record-keeping in favour of a “blockchain”, a
transaction
database that is distributed among users.
比特币对能源的渴求源于其设计。它放弃了中心化的记录储存方式，转而采用“区块链”（一种分布在用户之间的交易数据库）。
The blockchain is maintained by “miners”, who validate transactions by competing to crack mathematical puzzles with solutions that are hard to find but easy to check. Each successfully mined block of transactions generates a reward, currently 6.25 bitcoins ($357,000).
区块链由“矿工”维护，他们通过竞相破解数学难题来验证交易，这些难题的答案很难解出，但查验却很容易。每当人们成功挖出一个交易区块就会产生一笔奖励，目前是6.25个比特币（约合35.7万美元）。
The system varies the difficulty of the puzzles to ensure that one new block is created, on average, every ten minutes. High bitcoin prices make it worthwhile to spend more computing power—and therefore electricity—chasing mining rewards.
系统会调整题目的难度，以确保平均每10分钟就会生成一个新的区块。价值高昂的比特币值得人们花费更多的计算力（也可以说是电力）去追逐挖矿的奖励。
But bitcoin’s automatic stabilisers will ramp up the mathematical difficulty in response. Like the Red Queen in “Through the Looking-Glass”, competing miners find themselves running faster simply to stand still.
但比特币的自动稳定机制会相应地加大数学题目的难度。就像《爱丽丝镜中奇遇记》中的红皇后一样，相互竞争的矿工们发现，自己明明在加速奔跑，却仍停留在原地。
Despite the currency’s democratic ambitions, mining is concentrated among a handful of professional operators. About 70% takes place in China. The researchers use economic modelling to try to work out how much carbon all this make-work produces.
尽管比特币有着民主的野心，但挖矿主要还是被少数专业经营者所控制。比特币大约70%的矿是在中国挖出的。研究人员运用经济模型，试图计算所有这些无用功所产生的碳排放。
They conclude that, without regulation, Chinese bitcoin mining could consume around as much energy as Italy or Saudi Arabia by 2024. Annual carbon emissions, at 130m tonnes, would approach those of Nigeria.
他们的结论是，在缺乏监管的情况下，到2024年，中国比特币挖矿所消耗的能源将等同于意大利或沙特阿拉伯整个国家的能源消耗量。每年所产生的碳排放量将达到1.3亿吨，接近尼日利亚整个国家的碳排放量。
Such numbers should be taken with a good deal of salt. Bitcoin’s energy use depends crucially on its price, which swings wildly. The authors assume that the long-term trend will be upward, because the rate at which new bitcoins are created is designed to halve every four years.
当然，这些数据的可信度有待考证。比特币的能源消耗关键取决于其价格，而它的价格波动很大。作者认为，比特币价格的长期趋势是上升的，因为按照设计，新币的生成速度是每四年减缓一半。
Reality will doubtless prove more complicated. But the general picture—that bitcoin is a dirty business—fits with other research. One oft-cited model, which uses publicly available blockchain data, reckons its global energy consumption is already equal to that of Kazakhstan, and that its carbon footprint matches Hong Kong’s.
实际情况无疑更为复杂。但比特币作为一门污染环境的生意这一总体情况与其他研究相符。一个使用公开的区块链数据搭建的模型经常被引用，该模型估计，比特币的全球能源消耗量与哈萨克斯坦相当，其碳足迹与香港相当。
(红色标注词为重难点词汇)
本文翻译：Vinnie
校核：Vinnie
编辑：Vinnie
随着比特币的持续大热，与之相关的环境污染问题也引发了人们思考。近日，几位中国学者的一项研究认为，中国的矿工占比特币网络算力的75%以上，如果没有适当的干预措施和可行的政策，密集的比特币挖矿将可能破坏中国的减排努力。
重难点词汇：
cryptocurrency
[ˈkrɪptoʊkɜːrənsi] n. 加密货币
