Three ways to shut a drain. A price, like the bag charge. A cap, like the permits. And a rule: you may not. A rule says what may be sold, not what it costs. A price leaves the choice and makes it dearer. A rule takes the choice away.
1987: signed→A timetable, cut to zero→99 in 100 no longer made→About 2040: back
The rule that worked everywhere. In the 1980s chemicals in fridges and spray cans were eating the ozone layer. In 1987 countries signed the Montreal Protocol: a timetable for making less, later cut to zero; every country joined. Making them has all but stopped: 99 in 100 no longer made. The layer should be back around 2040, 2066 above Antarctica.
A few makers
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A ready swap
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A hole that would not wait
Why a rule and not a price for the ozone chemicals?
Because prices never work.
Not yet. Lesson 6 watched a five-pence charge remove 98 in 100 of something. Prices work. The question is which tool fits the drain.
Because nobody could count the chemicals.
Not yet. They could and did, which is how anyone knows 99 in 100 are no longer made. The count was the easy part; it is why the rule could be checked.
A few makers, a ready replacement, and a hole that would not wait. A timetable to zero was simpler to check than finding the right price.
Right. A rule is easy to police when there are few factories to inspect and a swap already on the shelf. Some countries used a tax or traded permits to meet their share of the timetable, inside the rule.
2009100 watts: the bulb banned that September
201075 watts: the bulb banned that September
201160 watts: the bulb banned that September
201240 watts: the bulb banned that September
The light bulb. From 1 September 2009 the EU banned the sale of the old filament bulbs, biggest first: the 100-watt that year, the 75-watt in 2010, the 60-watt in 2011, and the last 40- and 25-watt bulbs in September 2012. A rule often arrives in steps, so the makers have time to switch what they make.
Put the EU's bulb rule in the order it happened.
Tap them in the order they happen, first to last. Each tap gets a number.
2009: 100 W→2010: 75 W→2011: 60 W→2012: 40 and 25 W
Right. Biggest first, one step a year from 2009 to 2012. The order is the point: the bulbs that used the most power went first, and the makers had three years to fill the shelves with the replacement.
in 100 of jet fuel
01225
20252040
The UK's ladder
A newer rule, on jet fuel. From 2025, 2 in 100 of the UK's jet fuel must be made from waste or with clean electricity, never from crops or oil: 10 in 100 by 2030, 22 in 100 by 2040. The EU's ladder reaches 70 in 100 by 2050. The rule binds the fuel sellers, who pass on the cost.
Move the year and compare the two ladders. These are the rules as written; the shares are the law's own numbers.
UK2 in 100 of jet fuel
EU2 in 100 of jet fuel
Year: 2025
2025. Both start at 2 in 100 of the fuel.
UK10 in 100 of jet fuel
EU6 in 100 of jet fuel
Year: 2030
2030. The UK asks for 10 in 100, the EU for 6.
UK15 in 100 of jet fuel
EU20 in 100 of jet fuel
Year: 2035
2035. The EU jumps to 20 in 100; the UK is at 15.
UK22 in 100 of jet fuel
EU34 in 100 of jet fuel
Year: 2040
2040. The EU asks for 34 in 100, the UK for 22.
Which ladder is stricter?
The EU, because it reaches 70.
Not yet. Seventy is the EU's 2050 rung, outside these frames. In 2030, the EU's rung is the lower one.
It depends on the year. The UK is ahead in 2030; the EU is ahead from 2035.
Right. Two rules with the same start and different slopes cross. Reading one year tells you which is stricter that year, and nothing else.
The UK. Its first big number is higher.
Not yet. Ten beats six in 2030, and then the EU passes it. A rule is a ladder, not a single rung.
Move the control.
Each card is a bill on a drain. Is it a price, a cap, or a rule?
One card at a time. Tap the pile it belongs to.
Card 1 of 6
10p for a carrier bag
Permits for smoke, fewer printed each year, bought and sold
No new filament bulbs may be sold
£126 for every tonne buried in the ground
2 in 100 of jet fuel sold must be made from waste or clean electricity, not oil
A fixed number of fishing shares for the year, which boats can trade
10p for a carrier bag → A price
Not yet. A price. The bag is still allowed; it just costs something. The choice stays with the shopper.
Permits for smoke, fewer printed each year, bought and sold → A cap
Not yet. A cap. The total is fixed by the number printed, and the trading finds the price.
No new filament bulbs may be sold → A rule
Not yet. A rule. There is no price at which the shop may sell one. The choice is gone.
£126 for every tonne buried in the ground → A price
Not yet. A price, collected as a tax. Burying is still allowed, at that cost per tonne.
2 in 100 of jet fuel sold must be made from waste or clean electricity, not oil → A rule
Not yet. A rule, on the fuel sellers. It fixes a share that must be met. They may pay a set fee instead, so a price hides inside the rule.
A fixed number of fishing shares for the year, which boats can trade → A cap
Not yet. A cap. Lesson 3's halibut: the total is set by the count, and the shares are what trade.
2Price
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2Cap
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2Rule
Right. Two of each. A price makes the thing dearer. A cap fixes how much and lets the trade find the price. A rule removes the thing from the shelf. Every bill on a next-door cost is one of these three.
A few makers, a ready swapozone, bulbs
vsvs
Carbonfrom everything, no one swap
The ozone rule worked and the bulb rule worked. A friend says: so rules always beat prices. What did those two cases have in common that a tonne of carbon does not?
They were both about the air.
Not yet. Carbon is about the air too. What differs is how many sources there are and whether a swap is on the shelf, not which part of the sky is involved.
A few makers and a ready replacement. Ban the old thing and the new one sells. Carbon comes from everything and has no single swap.
Right. A rule needs something to point at. The ozone chemicals came from a handful of plants; the bulb had a drop-in replacement. Carbon comes from every car, boiler, cow and furnace, which is why the price and the cap are used alongside the rules.
They were both European.
Not yet. Montreal has been joined by every country on Earth. The bulb rule was the EU's. Where a rule is made is not what made it work.
Lesson complete
A rule says what may be sold, not its price. It works best with few makers and a ready swap.