Climate is what you expect. Weather is what you get.
Scientists know climate was different in the past, due to evidence such as:
- Fossils of animals & plants that no longer live in the UK.
- Landforms, U-shaped valleys left by retreating glaciers.
- samples of ice sheets of Greenland.
Ice sheets: are like Time Capsules; layers of ice, oldest at bottom, youngest at top.
Interglacial: warm period.
Glacial: cold period.
Quaternary: last 2.6 million years of geological time.
The Eruption Theory & Case Study
The Eruption Theory:
Eruptions need to be large & explosive, they produce:
- Sulphur dioxide gas
Blanket of ash & gas will stop sunlight reaching Earth's surface Sunlight is reflected off the ask & gas, back into space. Lowers average temperature.
Mount Pinatubo, Philippines:
- Released 17 million tonnes of Sulphur Dioxide.
- Reduced global sunlight by 10%, cooling planet for a year.
Tambora, Indonesia: 'Year without summer'
- 2000 people died in Europe, Harvests failed.
- Effects lasted four to five years.
The Sunspot Theory
Sunspots: Black areas on the surface of the sun.
The darker or more sunspots there are, the more active the sun is.
Lots of spots mean more solar energy being fired out from the sun towards Earth.
- Little Ice Age & Medieval Warm Period may have been causes of sunspot activity.
- There were more volcanic eruptions during the Little Ice Age.
- Some climatic changes cannot be explained by eruption theory, but can be by sunspot cycles.
The Orbital Period
Earth's orbit changes over a long period.
- It is sometimes circular, and sometimes more of an eclipse.
- The Earth's axis tilts.
Changes alter the amount of sunlight Earth receives, also where the sunlight falls on Earth's surface.
Climate and Ecosystems
Ecosystems: Unit made up of living things & their non-living environment.
Food chain: Cycle in which plants & animals are linked together. Dependant on eachother.
2 possible causes to extinction:
- Strike by an asteroid.
- Volcanic eruption.
- Both would have thrown huge amounts of gas, ash and dust into the air, blocking out the sun. Plants would struggle to grow as climate cooled. Ecosystems would've broken down as food chains collapsed.
Extinction: a species of plant or animal dying out completely.
Ice Age: Megafauna Extinction
Mass Extinction: when a number of species died out together.
Megafauna: Big animals.
They were victims of 2 stresses humans and climate change.
- They migrated to find new areas where climate suited them, this disrupted the food chain.
- Climate change stress made them weaker than normal.
Humans also migrated to new areas. They hunted some of the megafauna, which mean't less food for carnivores.
- Agreement to reduce Carbon emissions.
- Some countries like UK & Germany have reduced emissions, but others like China have not. In future a tougher agreement is needed.
Changing the Atmosphere
Atmosphere: layer of Gases above Earth's surface
Greenhouse Effect: the way gases in the atmosphere trap heat. Let heat in, but prevent most of it getting out.
Extra Greenhouse gases which pollute the atmosphere are created by humans, by burning fossil fuels, and using energy. Most pollution is produced in MEDC's.
We need to think about:
- how to reduce emissions.
- how to persuade developing countries to slow down their growth in carbon emissions.
- how to protect vulnerable people from future impacts of climate change.
Enhanced: means working more strongly.
Thermal Expansion: Expansion as a result of heating, sea expands as it warms up.
- If ice sheets and glaciers continue to melt, sea levels could rise significantly.
- Over 90% of world's valley glaciers are shrinking
UK Climate Futures
Holding back rising sea levels is very expensive.
Costs of warmer UK:
- In summer; Droughts, and water shortages become more common.
- More illnesses such as heat stroke & skin cancer.
- Farmers might need to change crops to those that need less water & more sunshine.
- Some plants and animals might die out if it gets too hot.
Benefits of a warmer UK:
- In winter, heating costs could fall.
- More people could take more holidays in the UK, good for tourism industry.
- Fewer deaths in old people from cold.
- New crops might mean new sales opportunities.
STERN report: 'Spend now, or pay later'
- Spend 2% of our GDP reducing greenhouse gas pollution now, or global warming could reduce our GDP by 20%.