natural climate change Flashcards
what happens to the earths climate over time
It naturally changes, alternating between colder and warmer periods.
What is the Quaternary period?
The last 2.6 million years, with 60 cold and interglacial warm periods.
When did the last ice age end?
Approximately 25,000 years ago.
Name five periods shown on temperature graphs over the past 11,000 years.
Holocene Optimum, Roman Climate, Medieval Warm Period, Little Ice Age, Modern Warm Period.
What is a natural source of water vapour?
Evaporation from oceans, seas, and plants.
What are natural sources of carbon dioxide?
Volcanic eruptions, wildfires, and respiration.
How is methane naturally produced?
From oceans, soils (decomposition), and termites.
What natural sources emit nitrous oxide?
Soils and oceans.
What are Milankovitch cycles?
Changes in Earth’s orbit, tilt, and wobble affecting solar radiation received.
How often does Earth’s orbit change and what’s the effect?
Every 100,000 years; circular = cooler, elliptical = warmer.
How often does Earth’s tilt change, and what’s the impact?
Every 40,000 years; greater tilt = hotter summers, colder winters
What is Earth’s axial wobble and its effect?
Every 24,000 years, it changes seasonal temperatures
How do volcanic eruptions affect climate?
Ash blocks sunlight, causing cooling; CO₂ can also cause warming.
How do sunspots influence climate?
More sunspots = more solar energy = warmer periods.
What impact do asteroids and dust have on climate?
Dust blocks sunlight (cooling); asteroid fires release CO₂ (warming).
How do ocean currents affect global climate?
Warm currents raise temperatures; changes can shift climate patterns.
What do ice cores tell us about past climate?
They trap gases and ash, showing CO₂ levels and temperature data.
How does preserved pollen help in climate research?
Indicates past plant life, showing past climate conditions.
Why are historical sources like diaries and art used cautiously?
They may be subjective or inaccurate.
What do tree rings show about past climate?
Wider rings = warmer/wetter years; fossilized trees reveal ancient climate.
