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International Baccalaureate · IB Diploma · Economics · HL Topik 3 8:11 Narasi bahasa Inggris · Subtitle bahasa Inggris + 中文 disematkan langsung
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Since 2005 European firms have needed a permit for every tonne of carbon dioxide they emit.
自 2005 年起，欧洲企业每排放一吨二氧化碳都需要一张许可证。
For much of 2012 to 2017 a permit cost less than 10 euros, so firms had little reason to change.
2012 到 2017 年的大部分时间里，一张许可证不到 10 欧元，企业几乎没有改变的理由。
After surplus permits were removed, the price passed 100 euros a tonne in February 2023.
多余的许可证被移除后，价格在 2023 年 2 月突破每吨 100 欧元。
Why should pollution need a price at all?
为什么污染需要价格？
Because the market leaves out costs that fall on other people.
因为市场忽略了落在别人身上的成本。
That is market failure.
这就是市场失灵。
This topic covers four failures.
本主题涉及四种失灵。
Externalities make the market produce too much or too little.
外部性使市场生产过多或过少。
Common pool resources such as fisheries are over-used.
渔场等公共资源被过度使用。
Public goods are not provided at all.
公共物品根本得不到提供。
And even an efficient market gives no guarantee of fairness: the problem of equity.
即使市场有效率，也无法保证公平：这是公平问题。
An externality is a cost or benefit that falls on a third party outside the transaction.
外部性是落在交易之外的第三方身上的成本或收益。
Negative production externalities, such as pollution and congestion, put marginal social cost above marginal private cost.
负的生产外部性，如污染和拥堵，使边际社会成本高于边际私人成本。
Positive consumption externalities, such as vaccination and education, put marginal social benefit above marginal private benefit.
正的消费外部性，如疫苗接种和教育，使边际社会收益高于边际私人收益。
The market trades at 100 units and a price of 20, where marginal private benefit meets marginal private cost.
市场在数量 100、价格 20 处成交，即边际私人收益等于边际私人成本。
Add an external cost of 6 per unit: marginal social cost lies 6 above, and crosses marginal social benefit at 92 units and a price of 24.
加上每单位 6 的外部成本：边际社会成本高出 6，与边际社会收益在数量 92、价格 24 处相交。
The market over-produces by 8 units.
市场多生产了 8 个单位。
Each of those units costs society more than it is worth, so the welfare loss is the triangle, half times 8 times 6, which is 24.
每个这样的单位给社会带来的成本都高于其价值，所以福利损失是一个三角形：二分之一乘 8 乘 6，等于 24。
Now an external benefit of 6 on consumption.
现在是消费带来的每单位 6 的外部收益。
Marginal social benefit lies 6 above marginal private benefit, and meets marginal social cost at 108 units and a price of 22.
边际社会收益比边际私人收益高 6，与边际社会成本在数量 108、价格 22 处相交。
The market stops at 100, so it under-consumes by 8, and again 24 of welfare is lost.
市场停在 100，所以消费少了 8，同样损失 24 的福利。
Policy follows the diagnosis.
政策跟着诊断走。
A Pigouvian tax equal to the marginal external cost, 6 here, shifts private cost up to the social optimum.
等于边际外部成本的庇古税，这里是 6，把私人成本推高到社会最优。
A subsidy equal to the marginal external benefit does the reverse.
等于边际外部收益的补贴作用相反。
Regulation caps the quantity directly.
管制直接限制数量。
And tradable permits fix the total, and let the market find the price.
可交易许可证固定总量，让市场决定价格。
Suppose production carries an external cost of 3 per unit, and the government sets a tax of 3.
假设生产带来每单位 3 的外部成本，政府征收 3 的税。
On our market the new equilibrium has a price of 22 and a quantity of 96.
在我们的市场中，新均衡价格为 22，数量为 96。
Consumers pay 2 of the 3, since the price rises from 20 to 22; producers keep 19.
消费者承担 3 中的 2，因为价格从 20 升到 22；生产者得到 19。
The state collects 3 times 96, which is 288, while the quantity moves toward the social optimum.
政府征得 3 乘 96，即 288，同时数量向社会最优移动。
Common pool resources, such as fisheries, groundwater and the atmosphere, are rival but non-excludable.
渔场、地下水和大气等公共资源具有竞争性，但不具有排他性。
Each fish caught is gone, yet no one can be stopped from fishing.
每捕一条鱼，鱼就少一条，但谁也无法被阻止捕鱼。
Each user imposes costs on the others, so without property rights or quotas the resource is over-used: the tragedy of the commons.
每个使用者都给别人带来成本，所以如果没有产权或配额，资源就会被过度使用：这就是公地悲剧。
Sustainability frames the long-run evaluation.
可持续性是长期评价的框架。
A public good is non-rival, so one person's use does not reduce another's, and non-excludable, so no one can be stopped from using it: street lighting, national defence, flood control.
公共物品具有非竞争性，一个人的使用不减少别人的使用；也具有非排他性，谁也无法被阻止使用：例如路灯、国防和防洪。
Compare common pool resources, which are non-excludable but rival.
对比公共资源，它们不具有排他性，但具有竞争性。
The two exam cases travel together.
这两种考试情形常常一起出现。
Non-excludability creates the free-rider problem.
非排他性造成搭便车问题。
Everyone can benefit without paying, so no private firm can collect revenue, and the market under-provides the good or does not provide it at all.
每个人都可以不付费而受益，所以私人企业收不到收入，市场就会供给不足，甚至根本不提供。
So the state provides public goods from taxation, valuing them at society's willingness to pay.
因此政府用税收提供公共物品，按社会的支付意愿来估价。
Markets reward scarce resources, not need.
市场奖励稀缺资源，而不是需要。
The price mechanism answers the question for whom by willingness and ability to pay.
价格机制按支付意愿和支付能力回答“为谁生产”。
So a market outcome can be efficient yet very unequal.
所以市场结果可以有效率，却非常不平等。
That is the equity half of the efficiency and equity pair of key concepts.
这就是“效率与公平”这对核心概念中的公平一面。
The Lorenz curve plots the cumulative share of income against the cumulative share of people, from the poorest.
洛伦兹曲线以人口累计百分比（从最穷的开始）为横轴、收入累计百分比为纵轴。
Suppose the five quintiles receive 5, 10, 15, 20 and 50 percent.
假设五个五分位组分别得到百分之 5、10、15、20 和 50 的收入。
The curve passes through 20 and 5, 40 and 15, 60 and 30, and 80 and 50.
曲线经过 (20, 5)、(40, 15)、(60, 30) 和 (80, 50)。
The area under it is 30 percent of the square, so the Gini coefficient is 1 minus 2 times 0.30, which is 0.40.
曲线下方面积是正方形的百分之 30，所以基尼系数是 1 减 2 乘 0.30，等于 0.40。
Gini runs from 0, perfect equality, to 1, one person takes everything.
基尼系数从 0（完全平等）到 1（一个人拿走一切）。
Poverty may be absolute, when basic needs are unmet, or relative, when people are deprived compared with the social norm.
贫困可以是绝对的，即基本需要得不到满足；也可以是相对的，即与社会常态相比处于匮乏。
Governments respond with progressive taxation, transfer payments, and access to education and health care.
政府的应对包括累进税、转移支付，以及提供教育和医疗。
Each weighs the equity gain against costs to incentives and efficiency: the trade-off every essay must evaluate.
每种做法都要权衡公平的收益与对激励和效率的代价：这是每篇论文都必须评价的取舍。
Now a data response.
下面是一道数据题。
The EU Emissions Trading System, started in 2005, caps the total carbon dioxide that power stations, factories and airlines may emit.
欧盟排放交易体系始于 2005 年，限定电厂、工厂和航空公司可以排放的二氧化碳总量。
Firms need one permit per tonne; firms that cut cheaply sell spare permits, and heavy polluters buy them.
企业每排放一吨需要一张许可证；减排便宜的企业出售多余许可证，排放多的企业购买许可证。
Firms outside the EU pay no such price, so the EU is adding a carbon charge on some imports such as steel and cement, with payments due from 2026.
欧盟以外的企业不付这一价格，所以欧盟正对钢铁和水泥等部分进口商品征收碳费用，从 2026 年起缴纳。
China's national carbon market began trading in July 2021; it covers more emissions than any other, but its price has been far lower.
中国全国碳市场于 2021 年 7 月开始交易，覆盖的排放量居世界首位，但价格低得多。
Firm K, an EU steel maker, emits one million tonnes a year but holds permits for only 0.8 million.
欧盟钢铁企业 K 每年排放 100 万吨，但只持有 80 万吨的许可证。
It can cut 0.2 million tonnes at 60 euros a tonne, while permits cost 90 euros.
它能以每吨 60 欧元的成本减排 20 万吨，而许可证每吨 90 欧元。
Cutting costs 0.2 times 60, 12 million euros; buying permits costs 0.2 times 90, 18 million euros.
减排成本是 0.2 乘 60，即 1200 万欧元；购买许可证是 0.2 乘 90，即 1800 万欧元。
So Firm K cuts its own emissions and saves 6 million.
所以 K 选择自己减排，节省 600 万。
A permit price above the cost of cutting is what makes firms cut.
许可证价格高于减排成本，正是促使企业减排的原因。
Evaluate permits against a carbon tax.
评价许可证和碳税。
A permit scheme fixes total emissions and lets the market find the price; a tax fixes the price and leaves the quantity uncertain.
许可证制度固定排放总量，由市场决定价格；碳税固定价格，数量不确定。
Both give every firm the same price per tonne, so the cheapest cuts happen first.
两者都让每家企业面对相同的每吨价格，所以最便宜的减排先发生。
But the EU price stayed below 10 euros for years because too many permits were issued, while a tax gives a steady price that firms can plan around; Sweden has used one since 1991.
但因为发放的许可证太多，欧盟价格多年低于 10 欧元；而碳税给出稳定的价格，便于企业规划，瑞典自 1991 年起就在征收。
Both raise revenue if permits are auctioned, both face carbon leakage, and both need accurate monitoring.
如果许可证拍卖，两者都能带来收入；两者都面临碳泄漏，也都需要准确监测。
Judgement: tradable permits are better when the aim is a fixed emissions target and the cap is tight and falls over time.
结论：当目标是固定的排放总量，且上限严格并逐年降低时，可交易许可证更好。
A carbon tax is better when price stability matters most and the government cannot judge the right cap.
当价格稳定最重要、政府又无法判断合适上限时，碳税更好。
In practice the EU combined them: a tighter cap with a reserve that removes surplus permits works like a price floor.
实际上欧盟把两者结合：更严格的上限加上移除多余许可证的储备，作用类似价格下限。
China's low price shows that design matters as much as the choice of tool.
中国的低价格说明，设计和工具的选择同样重要。
Check yourself.
自我检查。
Can you define an externality, and draw the negative production case from 100 and 20 to 92 and 24, and the positive consumption case to 108 and 22, with a welfare loss of 24 each time?
你能定义外部性，画出从 (100, 20) 到 (92, 24) 的负生产外部性和到 (108, 22) 的正消费外部性，每次福利损失都是 24 吗？
Explain the Pigouvian tax, the subsidy, regulation and permits?
能解释庇古税、补贴、管制和许可证吗？
Tell a common pool resource from a public good, and explain the free-rider problem?
能区分公共资源和公共物品，并解释搭便车问题吗？
Explain why markets fail on equity, read a Lorenz curve and find a Gini of 0.40?
能解释市场为何无法实现公平，读懂洛伦兹曲线并算出 0.40 的基尼系数吗？
And weigh permits against a carbon tax with the extract's numbers?
能用材料中的数字权衡许可证和碳税吗？