Notes

http://climate.geologist-1011.net/HoloceneTemperatures.png (Take Picture)
Overall there has been a clear rise in climate change.
⦁ variations in solar energy - sunspot activity raises global temperature
⦁ volcanic eruptions - large quantities of volcanic dust in the ⦁ atmosphere shield the earth from incoming ⦁ insolation, lowering global temperature. For example, the eruption of Mount Pinatubo in 1991 caused a dip in global temperatures in the early 1990s
⦁ Milankovitch cycles or variations in the tilt and/or orbit of the earth around the sun
⦁ Eccentricity - The greater the eccentricity of the orbit (the more elliptical it is), the greater the variation in solar energy received
⦁ Axial Tilt -Greater tilts mean that the hemispheres closer to the Sun, i.e., during summer, will experience a larger amount of heat than when the tilt is less. In other words, regions in the extreme upper and lower hemispheres will experience the hottest summers and the coldest winters during a maximum tilt.
⦁ Precession- Aside from the tilt, the axis also wobbles like a top, which can cause temperature to vary more
Human causes
Human factors are the result of growing population and economic developments.
They include:
⦁ the burning of fossil fuels for transport, industry and power, producing carbon dioxide
⦁ world-wide deforestation, sometimes involving rainforest burning, which also produces carbon dioxide
⦁ car exhausts and nitrogen fertilisers, producing nitrous oxide
⦁ CFCs found in fridges, air conditioning and aerosols and as a biproduct of the production of polystyrene packaging, like pizza and burger boxes
⦁ methane, produced from rice fields, landfill sites and from both ends of cattle as the food demand increases so do the number of animals
⦁

Ice cores - Glacial ice contains dust, air bubbles, or isotopes of oxygen that can be used to interpret the past climate (by interpreting the concentration) at the time the snow fell and formed the ice.The thick layers of ice that accumulated over thousands of years provide a convincing summary record of the past global climate and scientists drill deep into icecaps to collect ice cores in order to obtain this data.
Tree rings - Since tree growth is influenced by climatic conditions, such as temperature and precipitation, patterns in tree-ring widths, density, and isotopic composition reflect annual variations in climate. In temperate regions where there is a distinct growing season, trees generally produce one ring a year, and thus record the climatic conditions of each year. Trees can grow to be hundreds of years old and so contain annual records of climate conditions
Pollen - Each species of plants produces pollen grains, which have a distinct shape. These shapes can be used to identify the type of plant from which they came. Since pollen grains rarely rot, they are well preserved in the sediment layers that form at the bottom of a pond, lake or in blanket peat. An analysis of the pollen grains in each layer can tell us what types of plants were growing when the sediment was deposited and then inferences can then be made about the climate based on the types of plants found in each layer.
Historical soucres- Climate change can be seen through records which could document events like the freezing of the river Thames in earlier centuaries which shows that global warming has caused the average temperature of the planet to increse.
Agriculture
⦁ Crop yields are expected to decrease for all major world crops.
⦁ Agricultural land on the edge of deserts becomes unusable, through the process of desertification.
⦁ Crops could be wiped out in low-lying areas that suffer from flooding. With less crops available on the world market, prices are likely to increase.
⦁ The growing season in some areas will increase. This is a benefit to places such as the UK as more crops could be grown.
Sea level changes
⦁ Coastal land is at risk, especially land on deltas.
⦁ Sea defences are under more stress.
⦁ Low-lying land is threatened so the lives of 80 million people across the globe are threatened.
Water and ice
⦁ More mass movement can occur as glaciers melt.
⦁ Communities that use the melt water from glaciers may see this supply decrease. This is especially the case in Asia.
⦁ Economies that rely on skiing as a form of income may suffer as the skiing season is reduced or disappears through lack of snow.
⦁ Locations suffering from water stress will increase in number.
⦁ Less fresh water will be available in coastal areas as it will mix with sea water, which is salty.
Population
⦁ People will migrate from areas suffering drought. Any that remain will be in danger of dying from starvation and lack of water.
⦁ 17 million people in Bangladesh alone will be threatened by flooding.
⦁ As the world population increases, more people will be living in cities located on the coast. More people will be affected by coastal flooding as a result.