The greenhouse effect
- Greenhouse gases such as water vapour, carbon dioxide and methane keep the Earth warm enough to support life.
- Radiation from the Sun (mainly short wavelengths) passes through the atmosphere and warms the Earth's surface.
- The Earth radiates energy as infrared radiation (longer wavelength). Greenhouse gases absorb some of this and re-emit it in all directions, warming the atmosphere.
Human activities
- Burning fossil fuels and deforestation increase the amount of carbon dioxide in the atmosphere.
- Animal farming (digestion and waste) and decomposing rubbish in landfill sites increase the amount of methane.
- Based on peer-reviewed evidence, many scientists believe human activities are causing the Earth's surface temperature to rise, resulting in global climate change.
- Climate models are simplified and there is uncertainty; the media may give oversimplified or biased reports.
Effects of climate change
- Sea levels rise, causing flooding and coastal erosion.
- Storms become more frequent and severe.
- The amount, timing and distribution of rainfall change.
- Temperature and water stress for humans and wildlife; changes in the food-producing capacity of some regions; changes to the distribution of wildlife species.
Carbon footprints
- A carbon footprint is the total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
- Ways to reduce it: using renewable or nuclear energy, saving energy, carbon capture and storage, carbon taxes and licences, carbon offsetting (such as planting trees) and carbon-neutral products.
- Problems: scientific disagreement, lack of public information, reluctance to change lifestyles, economic costs, and incomplete international cooperation.
Key terms
- Greenhouse gas
- A gas, such as carbon dioxide, methane or water vapour, that absorbs infrared radiation.
- Greenhouse effect
- The warming of the atmosphere by greenhouse gases absorbing and re-emitting infrared radiation.
- Global warming
- The increase in the Earth's average surface temperature.
- Climate change
- Long-term changes in weather patterns, linked to global warming.
- Carbon footprint
- The total greenhouse gases emitted over the full life cycle of a product, service or event.
- Carbon capture and storage
- Collecting carbon dioxide from power stations and storing it underground.
- Carbon offsetting
- Balancing emissions by actions such as planting trees.
- Peer review
- Checking of scientific work by other experts before it is published.