L7 - Climate change

• the earth is believed to be 4.55 billion years old
• the entire quaternary period is often called an ice age due to presence of a permanent ice sheet on antarctica
• we are in an interglacial period where there are still ice sheets covering greenland and antarctica
• climate change is the long term change in the weather
• global climate change occurs very slowly over thousands of years
• since 1914, the met office has recorded reliable climate data change using weather stations, satellites, weather balloons, radar and ocean buoys
• the earths average surface air temperature has increased by approximately 1 degree over the last 100 years
• sea levels have risen by 19 centimetres since 1990 and are expected to continue to rise - this is due to thermal expansion and ice melting
• for the era before there were reliable data records, we need to take clues from the proxy data such as tree rings, fossil pollen, ice cores and ocean sediments to estimate what the climate was like
• antarctic ice cores are crucial in understanding long term climate change. antarctica is a wilderness with no permanent residents so the layers of snow remain unaltered, like time capsules holding information
• the ice cores in antarctica can be drilled so that the information about what climate change was like can be analysed
• the deeper the snow drilled, the older the snow
• ocean sediments can also be used to analyse climate change, the deeper the ocean sediment the older it is and they act as a timeline for evidence of climate change
• cause of climate change - solar output

  the output of the sun increased slightly from 1900 to 1940. satellites have recorded the intensity of solar energy output using radiometres since 1978.
• cause of climate change - solar output

  however, in fact, the sun has barely changed in the last 50 years and has even decreased, so it cant be a cause of climate change
• cause of climate change - orbital changes

  the distance between the earth and the sun changes as the earth orbits, as the earth orbits closer to the sun, the climate becomes warmer and vice versa the other way
• cause of climate change - orbital changes

  the earths axis angle changes due to the gravitational pull of the moon and as the angle of tilt increases, the summers get warmer and vice versa
• cause of climate change - orbital changes

  the earth is not a perfect sphere so wobbles on its axis in a 20,000 year cycle
• cause of climate change - orbital changes

  these affect the distribution of the suns energy on earth but scientists say that orbital changes would not cause an ice age for at least 30,000 years
• cause of climate change - volcanic activity

  volcanic eruptions can temporarily cause climate change due to the ash blocking the suns energy and reflect the sunlight away
• scientists have proved that natural causes are responsible for climate change but these natural causes cannot account for the rate of climate change we are experiencing
• cause of climate change - fossil fuels

  fossil fuels account for approximately 50 percent of greenhouse gas emissions, and burning these fossil fuels for transportation, heating and manufacturing releases carbon dioxide
• cause of climate change - agriculture

  agriculture contributes to approximately 20 percent of global greenhouse gas emissions and emits methane from cows digestion microbes
• cause of climate change - agriculture

  as the worlds population increases, people need more food which contributes to more gases, including rice paddy fields which release methane
• cause of climate change - deforestation

  deforestation is used for agriculture, logging and building roads. trees absorb carbon dioxide which reduces the amount in the atmosphere, but when people cut them down, there is less absorption and it is released again if people burn the trees
• effect of climate change - environmental

  flood risk from heavy rain is one of the main risks in UK
• effect of climate change - environmental

  the UK may be affected by sea level rise in europe, putting the UKs coastal defences under increased strain
• effect of climate change - environmental

  extreme weather such as drought, heat waves and flooding is expected to increase across the UK
• effect of climate change - human

  the estimated cost of damage from flooding in the UK is expected to be £12 billion by the 2080s
• effect of climate change - human

  the risk of diseases such as skin cancers and heat strokes will be on the rise due to stronger sun
• effect of climate change - human

  drought is likely to put a pressure on food and water supplies in Sub-Saharan africa due to higher temperatures and less rainfall