OCR GCSE (9-1) Geography B: Geography for Enquiring Minds (J384) · Spec 2.1a, 2.1b and 2.1c
Changing Climate
Read the notes, then try the questions. Each one is marked the moment you press Check, and shows the right answer and why.
Key ideas
- Climate is the pattern of weather over many years. Weather is what happens on one day.
- Evidence for past climate comes from ice cores (air bubbles from the past atmosphere), tree rings (wider rings in warm, wet years), pollen records, old paintings and diaries, sea ice records and temperature data.
- Natural causes include Milankovitch cycles (small changes in the Earth's orbit and tilt that change how sunlight is spread across seasons and latitudes) and volcanic eruptions. Ash and gases from a big eruption can cool the planet for a year or two.
- The greenhouse effect is natural. Greenhouse gases absorb heat leaving the Earth's surface and send some of it back, which keeps the planet warm.
- The enhanced greenhouse effect is the extra warming from human activity. Burning fossil fuels adds carbon dioxide. Cattle farming adds methane.
- Melting land ice (glaciers and ice sheets) raises sea level. Sea ice is already floating, so melting it adds almost nothing.
- Impacts are felt worldwide: rising sea level, more heatwaves, drought, and heavier rain and flooding in some places. In the UK, expect wetter winters, hotter and drier summers, and more flooding.
Key terms
- Greenhouse gas
- A gas, such as carbon dioxide or methane, that absorbs heat leaving the Earth and traps it.
- Enhanced greenhouse effect
- Extra warming caused by human activity adding more greenhouse gases.
- Milankovitch cycles
- Natural changes in the Earth's orbit and tilt over tens of thousands of years.
- Ice core
- A tube of ice drilled from an ice sheet. Its air bubbles show the past atmosphere.
- Fossil fuel
- Coal, oil or gas, formed from ancient living things. Burning them releases carbon dioxide.
Common mistakes
- Saying Milankovitch cycles move the Earth further from the Sun for the whole year, or that they change greenhouse gas levels. They change how sunlight is spread across the seasons and latitudes.
- Mixing up the ozone layer and the greenhouse effect. They are different things.
- Saying greenhouse gases make their own heat. They trap heat that is already leaving the surface.
- Saying volcanoes explain the rapid warming of the last two centuries. Eruptions cool the climate for a short time.
Exam tip
Changing Climate is the only Section A topic with no case study, so your levels-marked answer must be built from ideas and evidence, not a named place. For an explain question, give a reason and then develop it with a link: because, which leads to, so.
Free practice questions
7 questions, 13 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.
- Question 1 · Multiple choice[1 mark]
How do greenhouse gases warm the Earth's atmosphere?
- Question 2 · Fill the gaps[2 marks]
Burning ___ fuels releases carbon dioxide, which strengthens the ___ effect.
Word bank: ozone · fossil · greenhouse
- Question 3 · Matching[3 marks]
Match each type of evidence to what it can show.
- Question 4 · Sort into groups[3 marks]
Sort each cause of climate change into natural or human.
Volcanic eruptions
Changes in the Earth's orbit
Burning coal for electricity
- Question 5 · Choose more than one[2 marks]
Which TWO statements about greenhouse gases are correct?
Choose 2.
- Question 6 · Put in order[1 mark]
Put these steps in order, starting with the human activity.
Use the arrows to put these in the right order, first at the top.
- 1Sea level rises
- 2Ice melts and warming oceans expand
- 3More heat is trapped in the atmosphere
- 4Global temperatures rise
- 5Fossil fuels are burned and release CO2
- Question 7 · Multiple choice[1 mark]
Which statement about Milankovitch cycles is correct?