Short wavelength radiation pass through atmosphere and reaches Earth, while some long wavelength is reflected into the upper atmosphere.
The Earth radiates longer wavelength; infra-red. Some escape into space but because of the greenhouse gases some radiation is absorb and re-radiated back to Earth warming it.
Therefore we get the greenhouse effect- not all bad but if increased global warming occurs.
-CO₂ -Nitrous Oxide -Water vapour
-Methane -Chlorofluorocarbons (CFCs) -Ozone
Evidence of Global Warming
Actual data- measured directly
Proxies- data which has been inferred from other sources (frozen isotopes, dendrochronology- tree rings, coral records)
Frozen isotopes; proportion of O18 to O16 tells us the air temperature
-Atmospheric carbon dioxide level can be measured
-They show us INTERGLACIALS - periods of global warming (ICE CORES)
Coral; proportions of different isotopes taken up by coral as the sea temperature changes
Dendrochronology; dating of trees using rings. Looking at this we can see what the environment was like at different times. Thicker the ring, the warmer the climate.
Causes of Global Warming
Human activity is said to be the cause of global warming (so activities that release carbon dioxide and methane into the atmosphere)
But it is questionable when looking at studies done to see the relationship between increased carbon dioxide and increased global temperature because it fluctuates.
Risk of flooding: melting ice caps provokes sea level rises
Climate Change: rainfall patterns are changing- areas are becoming more desert like. Heavier rains in tropical areas.
Effect on organisms: Increase in enzyme activity and so faster metabolic reactions but up to a point as enzymes start to denature. Seasonal life cycles are disrupted. Some species rely on the temperature for development.
Change in species distribution: migration may change. Plants could suffer more than animals as they can't move. Increase in diseases will kill off plants reducing biodiversity.