Climate Change

Climate Change

Past climate change.
1. Some natural causes of climate change.
  1. Earth's orbit changes a small amount once every 100000 years (Milankovitch cycles).
  2. Amount of energy from the Sun changes over an 11-year cycle.
  3. Volcanic eruptions put ash dust into the atmosphere causing a cooling effect.
  4. Large asteroid collisions can cause cooling as material blocks out the Sun. Asteroids hitting the Earth can cause huge fires which release massive amounts of carbon dioxide which has a warming effect.
  5. Ocean current changes can cause cooling and warming (e.g. UK, warm and wet climate because of warm Atlantic currents. Current can sometimes shift so there is a cooler climate for a short period of time.
The impact of climate change.
1. Case study: The Little Ice Age.
  1. A colder period in Northern Europe starting in the 15th century and lasting the mid 19th century.
  2. Crops did not grow well which meant less productivity and less food for people.
  3. The winters were very cold and the summers were short.
  4. Causes: Could be caused by... fewer sunspots or volcanic ash in the atmosphere. Unlikely to be caused by... humans because not enough industry to cause climate change.
  5. Evidence: Diaries, newspapers and paintings and the tree rings in the old trees are thinner during cold years.
2. The impact of climate change on megafauna.
  1. Megafauna such as mammoths, giant beavers and sabre-toothed tigers, had evolved during the Ice Age.
  2. The Ice Age ended and temperatures rose 5°C in 10000 years.
  3. The megafauna couldn't adapt to the warmer climate and became extinct. Hunting by early humans could also have been a factor in their extinction.
Present and future climate change.
1. Pollution.
  1. 1. Carbon dioxide and methane are greenhouse gases linked to human activity.
  2. 2. The rise in greenhouse gas emissions matches the start of the Industrial Revolution.
  3. 3. Current levels of carbon dioxide are thought to be at their highest for at least 650000 years.
  4. 4. Current levels of methane are thought to be at their highest for at least 900000 years.
  5. 5. Methane is 21 times more potent than carbon dioxide.
2. Greenhouse effect.
  1. 1. The Sun warms up the Earth's surface.
  2. 2. Some warmth radiates up from the surface and into the atmosphere.
  3. 3. Without greenhouse gases the warmth escapes back into space.
  4. 4. With the greenhouse gases, some warmth is trapped, in the same way the glass in a greenhouse traps warm air. We need greenhouse gases - Just not too many!
3. Greenhouse gases.
  1. As a country develops, the amount of greenhouse gases it releases into the atmosphere is increased. More carbon dioxide is produced because: there is more industry, e.g. steel and cement making, more energy is needed so more fossil fuels are burned, transport increases so more oil is burned as petrol and diesel and land is needed so there is deforestation (trees are often burned). More methane is produced because there is more demand for meat so there are more farm animals.
Climate change challenges.
1. The UK climate.
  1. Climate of the UK is mild (cool) and wet. Described as temperature maritime. Several factors impact om the UK's climate. Latitude affects how much Sun the UK gets and how strong it is during the seasons. The North Atlantic current (or drift) keeps the UK warmer than other places of the same latitude. Air masses bring weather conditions with them from where they originated. The UK is affected by five air masses. The prevailing winds are from the Atlantic Ocean in the south west. They pick up moisture from the sea and often bring rain to the UK.
2. UK climate change.
  1. Possible changes to the UK's climate include: average temperature rise. Less predictable rainfall patterns with drier summers. Changing seasons - possible longer summers and more extreme cold in winter. Changes will happen because: the North Atlantic current is likely to move which will probably reduce sea temperatures and bring less rainfall. More air masses will come from the north, bringing storms and perhaps more extreme cold in winter. The paths of depressions (which bring rain) may be altered by these changes in air masses and ocean currents.
3. Predicting the effects of climate change.
  1. In 2008 global carbon dioxide reached 380 ppm (parts per million).
    1. If concentrations go over 550 ppm, predictions are that global temperature rises will be 6°C or more.
      1. Possible consequences: Millions of people would lose their homes due to sea-level rises. Changes to world weather patterns would cause droughts and storms leading to famines and disasters. Animal and plant species would not be able to adapt fast enough to the changes.
    2. If concentrations stay under 550 ppm, predictions are that global temperature rises will not go over 2°C.
      1. Possible consequences: Sea level might rise by 1 m, causing coastal flooding. More storms and hurricanes. Some species may become extinct, others would shift to new zones.
Climate change in the UK.
1. Environmental impacts.
  1. Sea level rise will lead to loss of coastal land and increased erosion. Risk on low-lying cities flooding, e.g. London. More severe storms and longer summer droughts. Changes to fishing industries if fish species move to different waters. Ecosystem change could mean some plant and animal species move into new areas and new (invasive) species emerge. Warmer temperatures could encourage diseases such as malaria.
2. Economic impacts.
  1. And increase in refugees from other countries hit hard by climate change coming to the UK. Warmer weather may mean farmers can grow different crops and enjoy a longer growing season. Hotter summers could mean more people have holidays in the UK (so less air travel overseas). Damage to cities such as London from flooding would be extremely expensive and very disruptive. Cost of protecting places from flooding will be expensive and in some cases not practical. Housing design might need to be altered so that less water is wasted and higher temperatures are dealt with.
Climate change in Bangladesh.
1. Environmental impacts.
  1. River flooding (which is already severe) would become worse from heavier rains and sea level rise. Tropical storms could become even more frequent and may move further inland, doing more damage. The dry season is already getting longer and this could cause more droughts.
2. Economic impacts.
  1. A small rise in sea level (just a few cm) could massively reduce Bangladesh’s farmland and agricultural output. More river flooding would mean more damage to people’s homes and more disruption to lives and the economy. More intense tropical storms and storms spreading inland would increase damage to homes, lives and infrastructure. Bangladesh has a large, fast growing population; many are farmers who need land to work. The cost of protecting homes and businesses from flooding is more than people or the government can afford. Coastal flooding damages farmland by making the land too salty to grow crops. Shrimp farming is very important but rising sea temperatures may damage this from the aquaculture. Increased flooding will increase the spread of water-borne diseases.

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