5: Weather, climate & ecosystems

• Weather: the state of the atmosphere at a particular place and time
• Climate: the weather conditions prevailing in an area in general or over a long period
• Ecosystem: a community of living organisms and their non-living environment
• Global warming: the increase in earth’s average surface temp due to rise of greenhouse gases
• Climate change: large scale, long term shift in the planet’s weather -patterns or average temps
• The earth’s climate has always changed long before humans existed. There were warmer and colder -droids e.g in the ice age it was 9C colder
• Short, medium & long term

  • There is currently 50% less sea ice over the Arctic Ocean than there was 30yrs ago (S)
  • In the northern hemisphere, certain s-Evie’s of plants and birds seem to be appearing earlier in the year than they did 30yrs ago (S&M)
  • The Arctic may be ice free in 2100 (M)
  • Fossils of dead plankton can be compared to the salinity of the oceans, indicating more precipitation and warmer climates (L)
  • Tree rings can show climate change because the rings are wider im warm and wet conditions. These trees can date back to 6000 years (L)
• Ice cores

  Each layer of snow holds chemical evidence, concentrations over the last 420,000 years, and trapped gases that show lvls of CO2 in the atmosphere have gone up and down as part of the natural cycle.
• Causes of global warming (natural):

  • Changes in the earth’s orbit - the course of the earth’s orbit is shaped like an avocado. The distance changes the heat that can be received. from the sun.
  • Variations in heat from the sun - black patches on the sun’s surface increases the heat the sun gives off
  • Volcanic activity - ashes block sun’s radiation - volcanic winter, droplets forming from sulphur dioxide reflect back the sun’s rays
• Causes of global warming (human): Agriculture

  Modern agriculture majorly contributes to greenhouse gases and responsible to 14% of greenhouse gas emissions. In the last years, 476b tons of carbon emitted from farmland soils. Cattle produce 120kg methane a year per animal. Manufacturing, tractor use, shipping and electricity for cooling and heating accounts for 25-30% of US emissions
• Causes of global warming (human): Deforestation

  When forests are cut, carbon absorption cease and the carbon stored in the tree is released into the atmosphere as CO2. Forests store up to 100x more carbon than agricultural fields. 1.5b tonnes of CO2 released every year due to deforestation
• Causes of global warming (human): Fossil Fuels

  Many power stations across the world burn fossil fuels. When burnt, it releases CO2 and pollutants in the atmosphere