Global Warming and Greenhouse Effect

Causes
1. CO2
  1. Atmospheric CO2 conc has increased rapidly since the mid-19th century from 280ppm to nearly 380ppm
  2. CO2 conc is increasing as more fossil fuels like coal, oil, natural gas and petrol are burnt. Burning fossil fuels release CO2
  3. CO2 conc is also increased by the destruction of natural sinks (things that keep CO2 out of the atmosphere by storing carbon). They store the carbon as organic compounds
2. Methane
  1. Atmospheric CO2 has increased from 700ppb during the mid-19th century to nearly 1700 ppb in 2000
  2. Methane conc is increasing because more methane is being released into the atmosphere. E.g more fossil fuels are being extracted, there's more decaying waste and there are more cattle which give off methane as a waste gas.
  3. Methane is also being released from natural stores. As temperatures increase, it's thought these stores will thaw and release large amounts of methane.
3. Increase in human activities like burning fossil fuels, farming and deforestation has increased atmospheric conc of CO2 and methane. This has increased the greenhouse effect and caused a rise in average global temperature
Introduction
1. Global warming is the term for the increase in average global temperature.
2. Human activity has caused global warming by enhancing the greenhouse effect
3. The greenhouse effect is essential to keep the planet warm, but too much greenhouse gas in the atmosphere means the planet warms up.
4. Two of the main greenhouse gasses are CO2 and methane.
Effects of Global Warming
1. Crop Yield
  1. Increasing CO2 conc could also be increasing in crop yields (amounts of crops produced from an area)
  2. CO2 concentration is a limiting factor for photosynthesis, so increasing global CO2 concentration could mean crops grow faster, increasing crop yields.
2. Insect Pests
  1. May affect the life cycle of some insect species
  2. Increasing temperatures means some insects go through their larval stage quicker and emerge as adults earlier.
  3. Some species are becoming more abundant (e.g. warmer and wetter summers in some places have led to an increase in the number of mosquitoes
  4. Other species may become less abundant (e.g. some tropical insect species can only thrive in specific temperature ranges, so if it gets too hot fewer insects may be able to reproduce successfully.
3. Distribution of wild animals and plant species
  1. Some species may become more widely distributed (e.g. species that need warmer temperatures may spread further as the conditions they thrive in exist over a wider area
  2. Other species may become less widely distributed e.g. species that need cooler temperatures may have smaller ranges as the conditions they thrive in exist over a smaller area.
4. Climate change could also affect the number of wild animals and plants
  1. Some species are becoming more abundant because the temperatures are rising
  2. Other species are less abundant (e.g. polar bears because they need frozen ice and global warming is causing more sea ice to melt.

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