1. How has global climate changed
1.1. global warming and cooling
1.1.1. warming :increase in the global temperatures over a long period of time
1.1.2. cooling: decrease in global temperatures over a long period of time
1.2. changes in global climate since 1981
1.3. variation in the global climate or climatic patterns in the long term
2. natural causes of climate change
2.1. variations in solar output
2.1.1. sun emit varying amount of solar radiation due to changes in its magnetic field
2.1.2. increase in magnetic activity=increase in solar radiation
2.2. volcanic eruptions
2.2.1. global dimming
2.2.1.1. gradual reduction in the amount of sunlight reaching the earth's surface
2.2.1.2. temporarily cools the earth for months or years
2.2.1.3. particles reflect solar energy back into space
3. greenhouse effect work
3.1. natural process essential to life on earth
3.2. incoming shortwave radiation from the sun passes through the greenhouse gases found in the atmosphere.
3.3. some shortwave radiation is reflected by the earth and the atmosphere
3.4. most shortwave radiation is absorbed by the earth's surface which then heats up
3.5. the warmed surface emits long wave radiation to the atmoshpere
3.6. greenhouse gases absorb long wave radiation,warming the atmosphere
4. what is greenhouse effect
4.1. increase in the concentration of greenhouse gases in the atmosphere, leading to a rise in global temperature.
4.2. occured by human activity,gases released at a far greater rate than the natural emissions of GHGs
5. how does human activities lead to G.Warming?
5.1. Burning fossil fuels
5.1.1. formed from dead organic matter that decomposed over millions of years
5.1.2. important, produced more than 80% of global energy
5.1.3. large consumers: china,USA,Canda,UK
5.2. Deforestation
5.2.1. loss of forests due to the removal or clearance of trees in forested areas
5.2.2. fewer trees & plants to absorb c02
5.2.3. expose soil to sunlight,increase soil temp,rate of carbon oxidation in the soil. process which carbon in the soil reacts w oxygen in the atmosphere to produce c02
5.3. Changing land use
5.3.1. agriculture
5.3.1.1. cow farts,methane
5.3.1.2. tractors run on fossil fuels release c02
5.3.1.3. inorganic fertilisers,^ nitrous oxide in soil
5.3.2. industries
5.3.2.1. fossil fuels burned=GHGs,C02
5.3.3. Urbanisation
6. how it affects humans
6.1. sea level rise
6.1.1. increase in the mean height of the sea's surface between high tide and low tide.
6.1.2. melting glaciers, water in seas and oceans to expand
6.2. more frequent extreme weather events
6.2.1. ^ temp=^amt of water vapour and latent heat in a warmer atmpshere