Where does the heat that stays go? Almost all of it into the sea. Of every 100 units the planet has kept since 1970, about 91 went into the ocean, about 5 into the ground, about 3 into melting ice, and about 1 into the air. The air is what we feel. It is the smallest store.
The whole air1×
The top 2.5 metres of sea1×
The top 100 metres of sea40×
The whole ocean, 3,700 metres deep on average1,500×
How many times the air's whole heat store each one holds.
Water holds heat far better than air. The top two and a half metres of sea hold as much heat as the whole sky above them. So when the sea takes the heat, the air warms slowly and the sea warms only a little. That little is spread through a very large thing.
The ocean91%
The ground5%
Melting ice3%
The air1%
The air holds about 1 part in 100 of the extra heat. If the sea suddenly stopped taking any, what would happen to air temperatures?
Nothing. The air's share stays at 1 in 100.
Not yet. The share is not fixed. It is what is left after the sea has taken its part. Close the sea, and what is left is nearly everything.
They would climb much faster. The store that was taking nine tenths has closed.
Right. The sea has been taking heat away from the air for fifty years. Without it, nearly all the extra heat would have to sit in the smallest store, and the smallest store warms fastest.
They would fall. The sea is what warms the air.
Not yet. The sea has been taking heat, not giving it. It gives some back in an El Niño year, but over decades it has been the place the heat went to, which is why the air has warmed as slowly as it has.
Warm water swelling7 cm
Mountain glaciers melting7 cm
Greenland and Antarctica ice4 cm
Water people pumped from underground, ending in the sea2 cm
Sea level rise since 1900, by cause, rounded.
Water swells as it warms. Heat a full kettle and it spills a little. The sea does the same, and it has 3,700 metres of water to swell. Warming alone has lifted the sea by about 7 centimetres since 1900, before a single glacier is counted.
Greenland's loss each year270 billion tonnes
Ice needed for one millimetre of sea360 billion tonnes
Melting 360 billion tonnes of ice raises the whole sea by 1 millimetre. Greenland loses about 270 billion tonnes a year. About how many millimetres a year is that?
mm a year
Divide Greenland's loss by the amount that makes one millimetre.
Right. Under a millimetre from Greenland alone. Add Antarctica at about 150, mountain glaciers at about 250, and the swelling of warm water, and you reach today's rise of about 4 millimetres a year.
0 cm12 cm24 cm
19002024
Sea level since 1900, rounded.
The sea has risen about 21 centimetres since 1900, and the rise is speeding up. It ran under 2 millimetres a year through most of the last century. It runs about 4 a year now. It does not arrive as a flood on a Tuesday. It arrives as higher high tides, and storm floods reaching streets they used to miss.
Four stores for the extra heat. Tap the one that decides whether tonight feels warm.
Tap the part of the picture that answers it.
The ocean91%
The ground5%
Melting ice3%
The air1%
The air
Right. The smallest store is the one we live in. Every temperature headline is about this sliver. The other 99 are working out of sight, and slowly.
The ocean
Not yet. The biggest store, and what it does reaches us as sea level and storms, not as tonight's temperature. It sets the air's temperature over decades, not evenings.
The ground
Not yet. Soil and rock warm a metre or two down. You feel that as the ground, not the evening air.
Melting ice
Not yet. Ice takes heat without getting warmer: the heat goes into turning it to water. That store shows up as sea level, not as a warm night.
Slide the marker to how much the sea has risen since 1900.
Slide the marker to your guess, then lock it. Nothing is scored.
123
you said · 0 cm
actually · 21 cm
0 cm50 cm100 cm
1A phone, end to end15 cm
2A school ruler30 cm
3A kitchen worktop's height90 cm
Sea level rise since 1900: —
Guesses run high, because a metre is the number people remember from forecasts for 2100, or low, because 21 centimetres sounds like nothing. Twenty-one centimetres on every coast at once is the difference between a storm tide stopping at the wall and coming over it.
Put in order how a hot year in the air ends up as water in a street.
Tap them in order, first to last.
Heat kept→Into the sea→Water swells, ice melts→Sea rises→Tide reaches further
Right. The step people skip is the middle one. The sea does not rise because the air is hot. It rises because the water itself is warmer and bigger, and because ice that was on land is now in it.
Lesson complete
Nine tenths of the extra heat goes into the sea, and warm water takes up more room.