How natural and human processes affect the global energy balance

What is climate change?

A long-term change in average global temperature and weather patterns.

What is global warming?

The long-term increase in Earth’s average surface temperature.

What is the greenhouse effect?

The process by which greenhouse gases trap heat in the atmosphere.

What is the enhanced greenhouse effect?

The strengthening of the natural greenhouse effect due to human activities.

What are greenhouse gases?

Atmospheric gases that absorb and re-radiate infrared radiation.

Name four main greenhouse gases.

Carbon dioxide, methane, nitrous oxide and water vapour.

Which greenhouse gas contributes most to anthropogenic warming?

Carbon dioxide (CO₂).

Why is methane a powerful greenhouse gas?

It traps significantly more heat than CO₂ over a short time period.

How do volcanic eruptions affect climate?

They release ash and aerosols that reflect solar radiation, causing short-term cooling.

How do solar cycles influence climate?

Changes in solar output alter the amount of energy reaching Earth.

What are Milankovitch cycles?

Long-term changes in Earth’s orbit, tilt and wobble affecting climate over thousands of years.

Why are natural causes insufficient to explain current warming?

They operate over long timescales and cannot explain rapid recent temperature rise.

What is the main human cause of climate change?

Burning fossil fuels for energy, transport and industry.

How does fossil fuel combustion increase warming?

It releases large amounts of CO₂ into the atmosphere.

How does deforestation contribute to climate change?

It reduces carbon sinks and releases stored CO₂.

Why is agriculture a contributor to climate change?

Livestock produce methane and fertilisers release nitrous oxide.

How does industrial activity increase greenhouse gases?

Manufacturing and cement production release CO₂ and other gases.

What is the carbon cycle?

The movement of carbon between the atmosphere, biosphere, hydrosphere and lithosphere.

What is a carbon sink?

A system that absorbs more carbon than it releases (e.g. forests, oceans).

How have humans altered the carbon cycle?

By increasing emissions and reducing natural carbon sinks.

What is a positive feedback loop in climate change?

A process that accelerates warming once it begins.

Give an example of a positive feedback loop.

Melting ice reduces albedo, increasing heat absorption and further melting.

What evidence links humans to climate change?

Rising CO₂ levels closely match fossil fuel use since the Industrial Revolution.

What atmospheric evidence supports climate change?

CO₂ concentrations have risen above 420 ppm, higher than at any time in 800,000 years.

Why is the current rate of warming significant?

It is much faster than past natural climate variations.