What the Cell
D4.3

Climate change

HL extension
3 hours4 statementsTextbook pp. 834–837

Guiding questions

  1. What is driving climate change?
  2. How does climate change affect ecosystems?

Slides

Slides PDF
Slide 1 of 12

Notes

Written for this site from the class slides, with textbook page references for each statement. The chapter is on pages 834–837 of the course textbook. Image credits are on slide 12.

Timing

D4.3.9

Phenology

p. 834

Phenology is the study of the timing of biological events such as flowering, budburst, bud set, migration and nesting. Day length and temperature are the main cues.

D4.3.10

Loss of synchrony

pp. 835–836
Slide: graph of caterpillar peak moving earlier faster than the peak food demand of great tit chicks

Species may use different cues, so warming can put linked events out of step. Arctic plants grow earlier while reindeer still arrive by day length. Caterpillars peak earlier, and great tit chicks can hatch too late for them.

Life cycles and evolution

D4.3.11

More insect generations

pp. 836–837

Warmth speeds insect development. Spruce bark beetles in northern regions can move from one generation a year to two, so more beetles attack each tree and more trees die.

D4.3.12

Evolution

p. 837

With less snow, pale tawny owls are more visible and catch less food, so brown owls have become more common in Finland. In Scots pine, a longer growing season favours later bud set, so alleles for later bud set can rise in frequency.

Videos

Select a video to play it here. Select it again to close it.

Note-taking sheet

Print this guide and complete it as you work through the slides and videos. It asks for your own explanations, so close the notes while you try each section.

PDF to print

First page of the note-taking sheet

Quick self-check

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Practice questions

A printable worksheet covering all four statements, from quick recall to data questions and a longer answer. It has 30 marks and takes about 30 minutes, or you can do one section at a time.

Worksheet PDF

Your teacher has the mark scheme.

First page of the worksheet

Practical

Trends in the timing of spring

Data35 minD4.3.9, D4.3.10

You will need: Long-term phenology records, such as the published Kyoto cherry blossom dates, spreadsheet

  1. Plot flowering date against year
  2. Add a trend line, and calculate the change per decade
  3. Compare it with temperature data from the same period
  4. Discuss what would happen if pollinators did not shift at the same rate

Safety: No practical hazards.

Carry this out with your teacher's supervision and follow your school's lab rules.

Nature of science and TOK

Nature of science

Science as a shared endeavour

Phenology uses records from scientists, the public and even centuries-old documents, such as Kyoto's cherry blossom dates.

Theory of knowledge

How reliable are knowledge sources from outside science?

Old diaries were never meant to be scientific data. Consider how they can be checked before being used as evidence.

Syllabus statements

Summarised in our own words. Use each code to find the exact wording in your textbook or the IB subject guide.

  • D4.3.9Phenology: studying when biological events happenp. 834
  • D4.3.10How climate change puts linked phenological events out of stepp. 835
  • D4.3.11How climate change lets insects fit more life cycles into a yearp. 836
  • D4.3.12Evolution in response to climate changep. 837

More of D4.3 in this course

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