GCSE · Geography · AQA · Spec 8035

Natural causes of climate change

Climate change isn't new. For millions of years, a wobbling planet, a spotty Sun, huge eruptions and asteroid strikes have been changing it, with no humans involved.

Follow the sunlight

Where does each cause change the sunlight?

Pick a cause, then pick where it belongs.

Where is the sunlight being changed?

Still to sort

At the Sun (0)

The Sun itself sends out more or less energy.

Where the line is: Nothing between the Sun and the Earth has changed. The source has.

In the Earth's orbit and tilt (0)

The Sun is the same, but the Earth's path and tilt change the energy it receives.

Where the line is: Nothing is blocking the sunlight. The Earth itself has moved.

In the atmosphere (0)

Something high in the air blocks sunlight or bounces it back.

Where the line is: The Sun and the orbit are unchanged. Something is in the way.

7 of 7 still to sort.

Seven natural causes of climate change. Sort them one way, then switch the rule and sort them again.

Start at the source

Sunspots are dark patches on the Sun's surface. Make your call before you read on.

The Sun goes through a spell with MORE sunspots than usual. What happens to the Earth?

Milankovitch cycles

Three ways the Earth's orbit and tilt change

View: All three. Showing 4 layers: Sun, orbit and Earth, Orbit shape, Tilt, Wobble

View

Layers

Explore

pick a view, then tap a cycle

Three separate movements, three different speeds. Tap each one to see what it does.

These changes are natural, and they play out over thousands of years.

Volcanic eruptions

Reason it through

How can a red-hot volcano end up cooling the whole planet?

Link 1 of 4

First link · your turn

A large volcano erupts. What does it release?

Locked — reveal the link above first

Check your thinking

Which of these sounds right to you?

Your friend says: "Climate change is a human thing. Before us, the climate just stayed the same. And a massive volcano would heat the planet up. It's full of lava!"

Which idea is closest to what you think right now?

Your friend is right: the climate only changes because of humans.Natural things can change the climate, but a volcano would warm it, because it's so hot.A big asteroid strike would warm the planet, because the impact releases so much energy.Natural causes change the climate too, and big eruptions and impacts cool it by blocking or reflecting sunlight.

How sure are you?

I'm sureI think soI'm guessing

Your friend is right: the climate only changes because of humans.

This is a common misconception

Natural factors have been changing the Earth's climate for millions of years, with no human influence at all. You've already met four of them in this lesson: the Milankovitch cycles, the Sun's changing output, volcanoes and asteroid collisions.

Natural things can change the climate, but a volcano would warm it, because it's so hot.

This is a common misconception

Half right. Natural factors do change the climate, but a large eruption cools it rather than warming it. The lava is hot, but what matters for the climate is what the eruption puts high in the atmosphere: particles that block and reflect sunlight.

A big asteroid strike would warm the planet, because the impact releases so much energy.

This is a common misconception

It works like the volcano, not like a heater. A large impact cools the Earth, because the dust, ash and gases it throws up block incoming sunlight. That's why you sorted it into 'in the atmosphere' at the start.

Natural causes change the climate too, and big eruptions and impacts cool it by blocking or reflecting sunlight.

This matches the evidence

Spot on. Natural factors have changed the climate for millions of years. And for eruptions and impacts, the question isn't how hot or violent they are. It's what they do to the sunlight.

Climate was changing naturally long before humans. And for any cause, hot or not, follow the sunlight.

Your turn

Write it, then mark it

Explain how natural factors can cause the Earth's climate to change. [4 marks]

Your answer

0 words · your answer stays on this page and is not sent anywhere.

The mark scheme

Milankovitch cycles: changes in the Earth's orbit and tilt affect the amount of solar energy the Earth receives. (1 mark)
Solar output: more sunspots mean greater solar output, which warms the Earth (fewer sunspots mean slightly cooler temperatures). (1 mark)
Volcanic eruptions release ash and dust that block sunlight, or sulfur dioxide that forms sulfate aerosols reflecting sunlight back into space. (1 mark)
Less sunlight reaching the surface causes cooling, e.g. short-term cooling after an eruption, or cooling after an asteroid impact blocks incoming sunlight. (1 mark)

Model answer

Natural factors change the climate by changing the Sun's energy that reaches the Earth. Over thousands of years, the Milankovitch cycles (changes in the shape of the Earth's orbit, the tilt of its axis and the wobble of that axis) affect how much solar energy the Earth receives. The Sun's output also changes: when there are more sunspots, solar output is greater and the Earth's surface warms, while fewer sunspots mean slightly cooler temperatures. Large volcanic eruptions throw ash and dust high into the atmosphere, where they block sunlight, and their sulfur dioxide forms sulfate aerosols that reflect sunlight back into space. With less sunlight reaching the surface, the Earth cools for a short time. A large asteroid impact cools the Earth in a similar way, because its dust, ash and gases block incoming sunlight.

The strongest answers link each cause to what it does to the sunlight, and then to warming or cooling. Naming the cause is only half the job.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

A wobbling planet, a spotty Sun, volcanoes and asteroids: how nature changes the sunlight the Earth receives.

What you need to know

Natural causes of climate change work without any human influence, and natural factors have changed the Earth's climate over millions of years.
The four natural causes are orbital changes (Milankovitch cycles), solar output, volcanic activity and asteroid collisions.
Each one changes the sunlight the Earth gets, in a different place: at the Sun, through the Earth's orbit and tilt, or in the atmosphere.

The big picture

Natural causes of climate change work without any human influence, and they have changed the Earth's climate for millions of years. There are four, and each changes the sunlight the Earth gets in a different place. Solar output changes at the Sun, rising and falling with sunspots over an 11-year cycle. The Milankovitch cycles change the Earth's orbit and tilt over thousands of years. Volcanic eruptions and asteroid collisions put material in the atmosphere that blocks or reflects sunlight, cooling the Earth.

Key points

1Milankovitch cycles are natural changes in the Earth's orbit and tilt over thousands of years. They affect how much solar energy the Earth receives, and so the timing of the seasons and the climate.

2Eccentricity: the orbit changes from more circular to slightly elliptical and back over about 100,000 years. A more elliptical orbit makes the Earth's distance from the Sun vary more, increasing seasonal differences.

3Axial tilt is currently about 23.5 degrees and moves over 41,000 years. The wobble (precession) takes 26,000 years and makes seasonal contrasts more extreme in one hemisphere and less extreme in the other.

4Solar output rises and falls with sunspots over an 11-year cycle. More sunspots mean greater output and warming; fewer mean slightly cooler temperatures.

5Large eruptions send ash and dust high into the atmosphere to block sunlight, and sulfur dioxide forms sulfate aerosols that reflect sunlight back into space. The result is short-term cooling, a volcanic winter.

6A large asteroid impact throws up masses of dust, ash and gases that block incoming sunlight, so it cools the Earth.

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Worked example

Problem

A student writes: 'Milankovitch cycles cause climate change because they make the Sun hotter.' What is wrong with this, and how should it be corrected?

⚠ Watch out

Mixing up the three Milankovitch cycles. Eccentricity is the SHAPE of the orbit (circular to slightly elliptical). Axial tilt is the ANGLE of the axis (about 23.5 degrees now). The wobble, or precession, is the axis slowly tracing a CIRCLE, like a spinning top. Shape, angle, circle.

🧠

Memory hook

Source, path, shade. The SOURCE changes (the Sun's output goes up and down with sunspots). The PATH changes (the Earth's orbit and tilt shift). Or something SHADES the Earth (volcanic ash and aerosols, asteroid dust). Follow the sunlight.

✓

Check yourself

Cover the page. Can you name all four natural causes of climate change, and say where each one changes the sunlight: at the Sun, through the Earth's orbit and tilt, or in the atmosphere?

Flashcards

(12)

What is a natural cause of climate change?

A factor or process that influences the Earth's climate without any human influence. Natural factors have changed the climate over millions of years.

What are the four natural causes of climate change?

Orbital changes (Milankovitch cycles), solar output, volcanic activity and asteroid collisions.

Name the three Milankovitch cycles.

Eccentricity, axial tilt and precession (the wobble).

What is eccentricity, and how long is its cycle?

The shape of the Earth's orbit around the Sun. It changes from more circular to slightly elliptical and back over about 100,000 years.

Why does a more elliptical orbit matter?

The Earth's distance from the Sun varies more, which increases the differences between the seasons.

What is axial tilt?

The tilt of the Earth's axis, currently about 23.5 degrees. It moves over a period of 41,000 years and affects the solar energy the Earth receives.

What is precession?

The wobble of the Earth's axis, like a spinning top. A complete wobble takes 26,000 years and makes seasonal contrasts more extreme in one hemisphere, less in the other.

What are sunspots?

Dark patches on the Sun's surface, caused by strong magnetic fields. Their number rises and falls over an 11-year cycle.

More sunspots: warmer or cooler Earth?

Warmer. More sunspots mean greater solar output. Fewer sunspots mean reduced output and slightly cooler temperatures.

How do volcanic ash and dust affect the climate?

A large eruption sends them high into the atmosphere, where they block sunlight. That causes short-term cooling, a 'volcanic winter'.

What do sulfate aerosols do?

They form from the sulfur dioxide an eruption releases. In the stratosphere they reflect sunlight back into space, cooling the Earth further.

How does an asteroid collision affect the climate?

It cools it. A large impact releases masses of dust, ash and gases that block incoming sunlight.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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Where does each cause change the sunlight?

Which of these sounds right to you?

Write it, then mark it

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