What do ice cores provide evidence of?

past levels of carbon dioxide and past temperatures. Bubbles of ancient air are trapped in the ice.

Which is a natural cause of climate change?

changes in the Earth's orbit. Milankovitch cycles act over tens of thousands of years.

What is the enhanced greenhouse effect?

extra warming caused by greenhouse gases from human activity. People have added to a natural effect.

Which gas is released by cattle and rice fields?

methane. It is a powerful greenhouse gas.

What effect does a very large volcanic eruption have on global climate?

short-term cooling. Ash and gas reflect sunlight for a year or two.

Climate change: evidence and causes · Cambridge IGCSE Geography (9

In plain words

The Earth's climate has always changed, through ice ages and warm periods. What is different now is the speed, and the cause. The evidence comes from thermometers, from ancient ice and from the shrinking of ice at the poles.

7 things to know

Evidence: temperature records show that the average global temperature has risen by about 1 °C since the late 1800s.
Ice cores drilled from Antarctica and Greenland contain bubbles of air trapped when the snow fell. They show how carbon dioxide and temperature have changed over hundreds of thousands of years.
Sea ice in the Arctic covers less area than it did, and glaciers are retreating. Old paintings, diaries and harvest records describe past climates.
Natural causes. Orbital changes (Milankovitch cycles): the shape of the Earth's orbit, the tilt of its axis and its wobble change over tens of thousands of years, altering how much energy arrives from the sun.
Sunspots: the sun's output varies slightly, in a cycle of about eleven years. Volcanic activity: a large eruption puts ash and gas high into the atmosphere, reflecting sunlight and cooling the Earth for a year or two.
The greenhouse effect is natural: gases in the atmosphere trap heat and keep the Earth warm enough to live on.
The enhanced greenhouse effect is the extra warming caused by people adding greenhouse gases: carbon dioxide from burning fossil fuels and from deforestation, and methane from cattle, rice fields and waste.

Worked example

Explain how burning fossil fuels leads to global warming.

Burning coal, oil and gas releases carbon dioxide into the atmosphere.
Carbon dioxide is a greenhouse gas: it absorbs heat given off by the Earth's surface.
More of it means more heat is trapped and less escapes to space, so the average temperature rises.

Tips and tricks

The greenhouse effect is natural and necessary. The problem is the enhanced greenhouse effect. Use the word "enhanced".
Volcanic eruptions cool the climate, for a short time. Do not list them as a cause of warming.

5 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Climate change: evidence and causes: 5 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

What do ice cores provide evidence of?
- the size of volcanoes
- past levels of carbon dioxide and past temperatures (the answer)
- the speed of ocean currents
- the number of sunspots
Bubbles of ancient air are trapped in the ice.
Which is a natural cause of climate change?
- burning coal
- cattle farming
- changes in the Earth's orbit (the answer)
- deforestation
Milankovitch cycles act over tens of thousands of years.
What is the enhanced greenhouse effect?
- the natural trapping of heat by the atmosphere
- extra warming caused by greenhouse gases from human activity (the answer)
- cooling caused by volcanoes
- a hole in the ozone layer
People have added to a natural effect.
Which gas is released by cattle and rice fields?
- oxygen
- nitrogen
- methane (the answer)
- helium
It is a powerful greenhouse gas.
What effect does a very large volcanic eruption have on global climate?
- long-term warming
- short-term cooling (the answer)
- no effect
- more rainfall everywhere
Ash and gas reflect sunlight for a year or two.

5 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

3 questions, 10 marks. Write your answers on paper, then check them.

Climate change: evidence and causes

Cambridge IGCSE Geography (9–1) 0976 · 10 marks · papermunch.org

Name ______________________________ Date ______________

Describe three pieces of evidence for climate change.[3]
Show answerHide answer
Records show that global temperatures have risen. Ice cores show changes in carbon dioxide and temperature over time. The area of Arctic sea ice has decreased.
I got this one
Explain two natural causes of climate change.[4]
Show answerHide answer
Orbital changes: variations in the Earth's orbit and tilt change the amount of solar energy received. Volcanic activity: ash and gas from large eruptions reflect sunlight, cooling the Earth for a time.
I got this one
Name three human activities that add greenhouse gases to the atmosphere.[3]
Show answerHide answer
Burning fossil fuels. Deforestation. Farming, especially cattle and rice.
I got this one

Answers: Climate change: evidence and causes

1. Records show that global temperatures have risen. Ice cores show changes in carbon dioxide and temperature over time. The area of Arctic sea ice has decreased.
2. Orbital changes: variations in the Earth's orbit and tilt change the amount of solar energy received. Volcanic activity: ash and gas from large eruptions reflect sunlight, cooling the Earth for a time.
3. Burning fossil fuels. Deforestation. Farming, especially cattle and rice.