changing climate

• Milankovitch cycles are changes to the Earth's orbit, tilt and rotation which affect how much solar radiation reaches the surface.
• The main cause of the ice age was the Milankovitch cycles
• The Milankovitch cycle is caused by gravitational forces from other planets that cause slight variations in the Earth’s orbit around the sun
• Eccentricity - The shape of the earth's orbit around the sun varies between circular and oval shaped over time
• Obliquity - The angle at which the axis tilts towards or away from the sun varies over time
• Ice sheets form when temperatures fall below freezing point (0 degrees) and snow falls on top of existing snow. The weight of new snow compresses it into ice. This process is called glaciation.
• Abrasion occurs when rocks rub against one another causing them to wear away. As the glacier moves, it picks up small pieces of rock and carries them with it. These rocks then scratch against the bedrock underneath the glacier, wearing it away.
• Natural Hazard vs Natural Disaster:

  • Natural Hazard: a natural process that can cause death, injury, disruption to humans, or destroy property and possessions (e.g. tropical storm, volcano)
  • Natural Disaster: a natural Hazard that has already occurred (e.g. Hurricane Katrina)
• Two main types of natural hazards:

  • Geological hazards: caused by land and tectonic processes (e.g. volcanoes, earthquakes, landslides)
  • Meteorological hazards: caused by weather and climate (e.g. tropical storms)
• Factors affecting hazard risk from natural hazards:

  • Human factors: population of the country, income level, coping mechanisms based on history
  • Natural factors: type, frequency, and magnitude of the natural Hazard, physical geography of the area (e.g. flat, mountainous, island, landlocked)
• Primary and secondary effects of natural hazards:

  • Primary effects: immediate impacts (e.g. building and road destruction, deaths and injuries, damage to crop and water supplies, infrastructure damage)
  • Secondary effects: effects that occur later (e.g. triggering of other hazards, blocked roads hindering aid, water and sanitation issues, economic weakening)
• Responses to natural hazards:

  • Immediate responses: evacuating people, treating the injured, rescuing, providing temporary supplies, foreign aid
  • Long-term responses: repairing infrastructure, improving forecasting and evacuation plans, promoting tourism for economic boost (e.g. Hawaii promoting volcanoes)
• Climate change is any significant change in the earth's climate over a long period
• Global warming describes the sharp rise in global temperature over the last century
• The Quaternary period is the most recent geological time period, spanning from about 2.6 million years ago to the present
• Before the Quaternary period, the earth was much warmer and stable before entering a cold glacial period lasting 100,000 years
• Evidence for climate change comes from various sources:
• Ice and sediment cores:

  • Ice sheets are made up of layers of ice, with one layer formed every year
  • By analyzing gases trapped in the layers of ice, scientists can determine the temperature each year
• Tree rings:

  • As a tree grows, it forms a new ring each year
  • Thicker rings indicate warm and wet conditions, helping scientists understand past climates
• Pollen analysis:

  • Pollen from plants preserved in sediment can show which species were living at a certain time
  • Comparing preserved pollen with current plant conditions helps scientists understand past climates
• Temperature records:

  • Global temperatures have been accurately measured since the 1850s using thermometers
  • Historical records like harvest states or newspaper weather reports extend the record of climate change further back
• Natural causes of climate change:
• Orbital change:

  • Earth's tilt and orbital shape affect solar radiation received, impacting temperature
• Volcanic activity:

  • Major eruptions release particles into the atmosphere, reflecting the sun's rays and cooling the earth's surface
• Solar output:

  • The sun's energy output varies due to short cycles, influencing climate
• Human causes of climate change:
• Burning fossil fuels:

  • Releases carbon dioxide into the atmosphere from coal, oil, natural gas, and petrol combustion
• Farming and livestock:

  • Produce methane, contributing to global warming
  • Rice paddies also contribute to global warming
• Deforestation:

  • Cutting down trees stops carbon dioxide absorption, impacting the atmosphere
• Cement production:

  • Made from limestone, releasing carbon dioxide into the atmosphere
• Mitigation strategies for climate change:
• Carbon capture:

  • Reduces emissions from power stations
• Planting trees:

  • Increases the amount of carbon dioxide absorbed
• Adaptation strategies for climate change:
• Changing agricultural systems:

  • Adapting to rainfall patterns and higher temperatures affecting crops
  • Using biotechnology to sustain optimum conditions or managing water supplies
• Recycling rainwater and wastewater to address water shortages in dry areas