What evidence is there to suggest climate change is a

• Patterns of climate change

  • the last 2.6 million years are the Quaternary period when there have been 60 cold periods with warmer interglacial periods
  • the last ice age ended 25,000 years ago.

  
• Evidence for climate change

  • ice cores, these trap air bubbles containing CO2 and microbes, providing information about past temperatures from the last 2.6 million years.
  • tree rings, each ring of the tree shows a year's growth, warmer and wetter periods trees grow more so the rings are larger.
  • art and diaries, provide evidence seen by people during past colder and warmer periods, the frost fairs on the river Thames in London in the 19th century.
• Natural greenhouse effect

  • greenhouse gases in the atmosphere allow short-wave radiation from the sun through to Earth's surface.
  • greenhouse gases absorb some of the long-wave radiating and stop it from radiation out into space.
  • this maintains the Earth's average temperature.
  • without the greenhouse effect the average temperature would be -18 degrees Celsius
• Milankovitch cycles

  • changes how much solar radiation Earth recieves.
  • orbit changes every 100,000 years, more circular orbit leads to cooler periods, more elliptical orbit leads to warmer periods.
  • tilt changes every 40,000 years, greater the tilt the hotter summers are and the colder winters are.
  • wobbles every 24,000 years on its axis and this can affect the seasonal temperatures.
• Human sources of greenhouse gases and enhanced greenhouse effect

  • carbon dioxide, burning fossil fuels in power stations and wood, deforestation as the fewer trees there are the less CO2 is removed from the atmosphere.
  • methane, decay of organic matter, manure, waste in landfill, crops and released by cattle and during rice cultivation.
  • nitrous oxide, artificial fertilisers, burning fossil fuels.
  • chlorofluorocarbons, air conditioning, refrigeration units, aerosols.

  
• Volcanic eruptions

  • large scale eruptions lead to vast quantities of ash ejected into the atmosphere.
  • this blocks solar radiation leading to a decrease in temperatures.
• Sunspot activityand atmospheric dust

  • dark spots appearing on the sun's surface.
  • increased sun spot activity is linked to higher average temperatures, sunspots indicate that the sun's effectiveness at radiating heat is increasing.
  • minimal role in climate change.
  • atmospheric dust due to asteroids entering Earth's atmosphere may increase the amount of dust which decreases temperatures.
• Enhanced greenhouse effects

  • fossil fuels, account for 50% of global greenhouse gas emissions, used in transport, construction, heating and manufacturing.
  • agriculture, production of fertilisers uses fossil fuels, artificial fertilisers increase the amount of nitrogen oxide released.
  • construction, the manufacture of cement releases CO2.
  • transport, increasing global population has led to an increase in cars and planes, most transport uses petrol which releases CO2.
• Sea level rise

  • an impact of climate change, risen 20cm since 1880.
  • estimated that 410 million people will be at risk from sea level rise by 2100.
  • thermal expansion, water expands when warm increasing the volume of water in seas and oceans.
  • melting glaciers, adding water.
  • melting ice-sheets, ice in the Arctic and Antarctic is melting.
• Social impacts of sea level rise

  • displacement of people from their homes.
  • food and water supplies threatened by drought and flooding, which leads to malnutrition and famine.
  • lack of freshwater due to reduced precipitation.
  • spread of disease due to higher temperatures and flooding.
  • crop yields in sub-Saharan Africa are estimated to reduce by over 20%.
• Environmental impacts of sea level rise

  • destruction of ecosystems like coral reef bleaching and wildfires destroying forests which leads to reduced biodiversity due to loss of plant and animal species.
  • changing patterns of animal migration and behaviour.
  • increased water temperatures in oceans and seas.
  • increased wildfires due to drier conditions.
• Economic impacts of sea level rise

  • high costs of building flood defences.
  • relocation of people and building of new homes is expensive.
  • loss of jobs and reduction in tourism due to impact on coastal resorts.
  • loss of crops reduces farmer's income and exports.
• Maldives

  • over 80% of its islands are less than 1m above sea level.
  • is seas continue to rise the islands will be unhabitable by 2050.
  • the government is constructing an artificial island called Hulhmalé, and building flood walls and defences around islands.
• Extreme weather events

  • warmer sea temperatures increase the amount of evaporation leading to more frequent and severe storms.
  • drought and heatwaves are becoming more common due to increasing average global temperatures.
  • extreme weather events are forcing people to move, the UN states an annual average of 21 million people were displaced by weather-related events between 2008-2016.
  • 1.2 billion people could be displaced by 2050.
• Weather patterns in the UK

  • by 2050 the UK will have higher average temperatures, wetter winters and drier summers.
• Social impacts of changing weather patterns

  • increased deaths due to extreme heat but fewer deaths from cold.
  • people with heart conditions will be affected.
  • in 2022 the extremes in temperature in Europe led to 61,000 excess deaths.
• Environmental impacts of changing weather patterns

  • ecosystems may be affected by drought, flooding and wildfires.
  • increase in wildfires due to drier conditions in summer.
  • changes in species in the UK and water around the UK due to higher temperatures.
• Economic impacts of changing weather patterns

  • tourism may increase due to warmer, drier climate in summer.
  • growing seasons will be longer, increase income for farmers and exports.
  • less water available for irrigation and power stations.