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SingaporeGeographySyllabus dot point

What is the evidence that the world's climate is changing?

Describe the main lines of evidence that show the climate is warming, and explain why scientists are confident in them

A clear, scaffolded answer to the N(A)-Level Geography outcome on climate change evidence. Rising temperatures, melting ice, rising seas and shifting species, why scientists are confident, and how to read the data.

Generated by Claude Opus 4.88 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The answer
  3. Examples in context
  4. Try this

What this dot point is asking

This outcome asks you to describe the evidence that the world's climate is warming and to explain why scientists are confident in it. The central idea is that no single measurement proves climate change on its own, but many separate lines of evidence all point the same way, which is what makes the conclusion so strong.

The answer

Rising temperatures

The clearest evidence is the record of global temperature. Thermometers around the world show that the average global temperature has risen by about 1 degree Celsius since the late 1800s, and the warmest years on record are recent. This is the most direct sign that the climate is warming.

Melting ice

A warming world melts ice, and this is happening:

  • Glaciers and ice sheets in places like Greenland and Antarctica are shrinking.
  • Arctic sea ice is getting smaller, especially in summer.

Shrinking ice is strong evidence of rising temperatures.

Rising sea levels

The sea is rising for two reasons: warmer water expands and takes up more space, and melting ice on land adds more water to the oceans. Tide gauges and satellites both record this rise, which threatens low-lying coasts.

Warming oceans and shifting species

Other evidence supports the picture:

  • The oceans are warming as they absorb extra heat.
  • Plants and animals are shifting their ranges toward cooler areas (toward the poles or higher up mountains), and some events like flowering happen earlier in the year.

Evidence from the past

Scientists also study the past climate using natural records such as ice cores (bubbles of old air trapped in ice) and tree rings. These show how temperature and carbon dioxide have changed over thousands of years and confirm that recent warming is unusually fast.

Examples in context

Example 1. Shrinking Arctic sea ice. Satellite images over recent decades show the area of Arctic sea ice in summer steadily shrinking. This is one of the most visible signs of a warming world and is often shown in data-response questions, where students describe the falling trend and link it to rising temperatures.

Example 2. Sea-level records and low-lying Singapore. Tide gauges and satellites record global sea level rising year on year. For a low-lying island like Singapore, this evidence is taken seriously: the rising trend is why the country studies future sea levels and plans coastal protection, linking global evidence to local action.

Try this

Q1. State two lines of evidence that the climate is warming. [2 marks]

  • Cue. Rising global temperatures and melting ice (also rising seas, warming oceans, shifting species).

Q2. Explain why a single hot day is not good evidence of climate change. [2 marks]

  • Cue. A single hot day is weather; climate change is shown by long-term trends over many decades, not one-off days.

Q3. Explain why rising sea levels are evidence of a warming world. [2 marks]

  • Cue. Warmer water expands and takes up more space, and melting ice on land adds more water to the oceans, so the sea rises.

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original6 marksDescribe three lines of evidence that show the world's climate is getting warmer.
Show worked answer →

Line one: rising temperatures. Records from thermometers around the world show the average global temperature has risen by about 1 degree Celsius since the late 1800s.

Line two: melting ice. Glaciers and ice sheets are shrinking and Arctic sea ice is getting smaller each year, which shows the world is warming.

Line three: rising sea levels. The sea is rising because warmer water expands and melting ice adds more water to the oceans.

What markers reward: three clear, distinct lines of evidence (rising temperatures, melting ice, rising seas; also warming oceans, shifting species, ice cores), each described with a fact or figure where possible.

Original4 marksExplain why scientists are confident that the climate really is warming, even though weather changes from day to day.
Show worked answer →

Scientists are confident because many different, independent lines of evidence all point the same way: rising temperatures, melting ice, rising seas, warming oceans and shifting species. When separate measurements agree, the conclusion is strong.

They also look at long-term averages (climate), not single hot or cold days (weather). A trend over many decades shows real warming, even though the weather goes up and down from day to day.

What markers reward: the idea that many independent lines of evidence agree, and the distinction between long-term climate trends and short-term weather.

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