Fourteen lessons, five ideas. The tap: what we pour in each year. The bath: what is already in the air. The store: where the heat goes and how slowly it answers. The edge: what a small shift in the average does to rare days. The swap: where energy comes from and what changing it runs into.
Emissions in 202240.4 billion tonnes
Emissions in 202340.9 billion tonnes
Take a headline: emissions hit a record high, but growth slows to 1 in 100. Both halves are about the tap. It opened a little wider than last year, and more slowly than it used to. It says nothing about the bath, which rose by about the usual amount either way.
0 per million238 per million476 per million
19902024
A headline reads: carbon dioxide in the air passes 425 parts per million. Which idea is it about?
The bath. It is a level, not a rate of pouring.
Right. Parts per million is how full the bath is. It goes up whether the tap opened or closed a little this year, because the tap is still far bigger than the drain.
The edge. It is a record.
Not yet. It is a record, but a record of the level in the air, not of a hot day. The edge is about what the warming does to rare weather; this is about the cause behind it.
The tap. It is about this year's emissions.
Not yet. This year's emissions would be in tonnes for the year. A level in the air, in parts per million, is what all the years have added up to.
Sort the headlines by which idea each one is about.
One card at a time. Tap the pile it belongs to.
Card 1 of 6
Emissions fell 2 in 100 last year
Carbon dioxide is now half again what it was in 1750
Delhi has its hottest June on record
The sea rose 4 millimetres this year
Airline emissions are back to where they were before the pandemic
The last ten years are the warmest ten
Emissions fell 2 in 100 last year → The tap
Not yet. This is the tap. Emissions in a year is how much was poured in that year.
Carbon dioxide is now half again what it was in 1750 → The bath
Not yet. This is the bath. It compares two levels of what is in the air, then and now.
Delhi has its hottest June on record → The edge or store
Not yet. This is the edge. A record month is the temperature crossing a line, which is what the bath has done so far.
The sea rose 4 millimetres this year → The edge or store
Not yet. This is the store. Sea level is where the warmth has ended up, deep in the water and the ice.
Airline emissions are back to where they were before the pandemic → The tap
Not yet. This is the tap. It is about how much airlines pour in each year, not what is already in the air.
The last ten years are the warmest ten → The edge or store
Not yet. This is the edge and the store. Temperatures are what the bath has done to the planet so far.
Tap: tonnes a year→Bath: parts per million→Edge and store: degrees and millimetres
Right. Rates for a year are the tap. Levels in the air are the bath. Temperatures and sea levels are what the bath has done so far: the edge and the store. A headline about the tap tells you nothing about the other two this year.
0°C0.9°C1.79°C
20212025
Warmer than the late 1800s, rounded.
Another headline: the world cooled in 2025 after a record 2024. True, and about the wobble. 2024 was an El Niño year and 2025 was not. Read the decade, not the year. The right question for any temperature headline is whether it is about one year or about thirty.
Britain's emissions have fallen by about half since 1990. In 1990 the air held 354 parts per million of carbon dioxide. Slide to where the level stood in 2023.
Slide the marker to your guess, then lock it. Nothing is scored.
12
you said · 250 per million
actually · 421 per million
250 per million350 per million450 per million
11750280 per million
21990354 per million
The level in 2023: —
Many people slide down, or barely up. One country's tap closing halfway hardly shows in a bath the whole world fills; the level rose from 354 to about 421. Britain's fall is real and it is the tap. The bath is everyone's.
A headline says solar is now 6 in 100 of the world's electricity. Tap the number that tells you what that is as a share of ALL energy.
Tap the part of the picture that answers it.
Electricity is only part of energy.
Solar's share of electricity6%
Electricity's share of all energy20%
Share of all energy from coal, oil and gas81%
Electricity's share of all energy
Right. Six in 100 of a fifth is about one in 100 of all energy, or two, depending how you count. The headline is true, and much smaller than it sounds. Every clean-electricity headline needs this bar beside it.
Solar's share of electricity
Not yet. That is the headline's own number. It is about electricity only, which is a fifth of the energy the world uses.
Share of all energy from coal, oil and gas
Not yet. That is the whole picture the headline sits inside, and worth keeping in view. It does not tell you what the headline's 6 means in the whole; the middle bar does.
Each year. A straight-line cut from today to zero in 2050.
One more: net zero by 2050. This is the tap closed to the size of the drain, by a date. Net means what we pour in minus what we take out. It is the one headline about stopping the bath's rise, not slowing it. Whether the date is early enough is a bath question: how full by then?
If the world cut emissions in a straight line from today's 41 billion tonnes a year to zero in 2050, about how much more carbon dioxide would go into the air first?
About 500 billion tonnes.About 500 billion tonnes: twenty-five years of a closing tap, which is half of twenty-five full years. That adds roughly a quarter of a degree, and it is why 1.5 degrees is now expected to be crossed in the 2030s whatever happens after.
A headline reads: record heat in Europe as emissions fall for the third year. Someone says the two halves cannot both be true. Who is right?
Both halves are true. The tap narrowed while the bath, the store and the edge all kept moving.
Right. A narrower tap still fills the bath. A fuller bath still warms the store. A warmer store still pushes rare days over the line. Three years of a smaller tap changes none of that yet.
The heat proves the emissions cut is not real.
Not yet. The cut is about the tap. The heat is about the edge, which follows the bath, which is still filling. A real cut and a record hot summer in the same year is what the course predicts.
The cut proves the heat is just weather.
Not yet. A heat record can be the wobble or the edge, and nothing about this year's tap decides which. The bath sets the edge, and the bath rose this year as it did last year.
Lesson complete
Every climate headline is about one of five things: the tap, the bath, the store, the edge, or the swap.