How climate has changed in the past and how do we
- Fossils of plants and animals that no longer live in the UK
- Landforms left by Glaciers
- Samples from ice sheets in Antarctica. Ice sheets are made up of layers of ice, a layer for each year. Trapped in the ice sheets are air bubbles. Climatologists study the CO2 levels to reconstruct past climates.
Natural causes of climate change
Eruption theory: very large and explosive volcanic eruptions change earth’s climate. Ash and gas spread around the stratosphere and stop sunlight reaching the earth’s surface.
Sunspot Theory: black areas on the sun’s surface. Sometimes there are more then they disappear. Spots mean greater activity and more solar energy being sent towards the earth.
Orbital Theory: Changes in the way the earth orbits the sun from circular to ellipse alters the amount of sunlight the earth receives. The earth’s axis also moves and wobbles about affecting how much sunlight is recieved.
Geological Climate Events
The dinosaur extinction was possibly caused by a massive asteroid hitting Mexico and a huge volcano in India combining- dust, ash, gas into the stratosphere- blocks the sun- cools the climate- plants don’t grow- dinosaurs have no food……..knock on effect through the food chain.
Megafauna extinction – big animals like the woolly mammoth. The climate was warming so they had to find new areas to live where the climate suited them. This disrupted food chains. Humans also hunted them to extinction.
How the greenhouse effect works and the types of h
Greenhouse gases (CO2 from the burning of fossil fuels, deforestation, Methane from paddy fields and cattle, Nitrous oxide from aircraft engines and fertilisers) trap heat from leaving the atmosphere and re-radiate that heat back down to earth.
Increase in concentraton = increase in heat trapped = warmer the earth beomes
We need the NATURAL grenhouse efect or the earth would be too cold.
How greenhouse gas levels have changed over time a
Since pre-industrial times, atmospheric concentrations of greenhouse gases have grown significantly as countries become more industrialised their people become consumers of energy and goods, as well as producers of air pollution through the burning of fossil fuels.
Most greenhouse gases are produced by developed countries.
The USA produces the most amout of Co2 each year.
Emerging powers such as China and India are now in line with older polluters such as USA and Europe due to the take off of their development. China is now the world’s largest single polluter.
What scientists think might happen to climate and
- Temperatures to rise between 1.1°c and 6.4°c by 2100
- Sea levels to rise between 30cm and 1 metre by 2100
- Floods, droughts and heat waves would become more common
- Storms and hurricanes would become stronger
Case Study: UK
Benefits of Climate Change:
- lower winter heating bills
- increase in levels of tourism
- growing seasons different = ability to grow new crops such as vines for wine
- more land can be farmed at higher altitudes
- fewer winter deaths from cold temperatures
Costs of Climate Change:
- droughts in summer
- more illnesses such as sun stroke and skin cancer
- melting of ice caps = increased sea levels = flooding of coastal areas
- milder winters = wetter winters = higher levels of flooding from rivers
- farmers have to hange crops they can grow
- extinction of some plants and animals
Case study: Bangladesh
Bangladesh is a developing country which often suffers from disastrous flooding. Global warming will only make the flooding worse. In Bangladesh increase in sea levels would lead to: · More and stronger cyclones · Accelerated coastal erosion · Reduced river flow because of increased evapotranspiration · Saltwater pollution of freshwater supplies in wells underground · Destruction of mangrove forests and other habitats along the coast · Increased pressure on land and resources inland
Case study: Bangladesh
Bangladesh is a developing country which often suffers from disastrous flooding.
Global warming will only make the flooding worse.
In Bangladesh increase in sea levels would lead to:
· More and stronger cyclones
· Accelerated coastal erosion
· Reduced river flow because of increased evapotranspiration
· Saltwater pollution of freshwater supplies in wells underground
· Destruction of mangrove forests and other habitats along the coast
· Increased pressure on land and resources inland