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Evidence for climate change
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- 1EVIDENCE FOR LONG-TERM, MEDIUM-TERM AND SHORT-TERM CLIMATE CHANGE:LONG TERM EVIDENCE: Ice cores are a reliable method of assessing long term temperature change. A core of ice is extracted from an ice sheet which is comprised of individual layers ( a new layer is formed each year). The gases trapped within each layer offer an indication of what temperatures were like when that particular layer was formed, allowing scientists to compare temperatures over time. For example, an ice core over 3000m deep was extracted from Antarctica, dating back to over 400,000 years ago.
- 2Pollen samples can also be used to measure long term change. Pollen can be preserved in sediment; scientists are then able to look at the particular species preserved and compare it with present day examples. By looking at the conditions required for certain species to grow, scientists can ascertain what conditions were like from the pollen sample.Raised beaches can offer an insight into how sea level has changed over time e.g. a raised beach suggests a higher water level, which suggests there was less water contained as ice, so temperatures must have been higher.
- 3MEDIUM-TERM CHANGE: For each year of a tree's life, a new tree ring is formed. If conditions that year were good, the tree ring will be thick. Using this knowledge, scientists can extract tree cores, measure the age of the tree and then assess how climate conditions have changed on a yearly basis. Tree rings can be used to show changing conditions for up to 10,000 years ago.Throughout history, humans have often documented weather patterns, seasonal changes and the success of a yearly harvest. This data can be used to see how conditions have changed and what impacts this may have had e.g. on agriculture.
- 4Glacial retreat can also indicate increasing temperatures; rocks that are deposited at the base of glaciers can be dated, so the further away the current base of the glacier is from the original rock shows the scale of retreat and temperature increase.SHORT-TERM CHANGE: Reliable weather records have been consistently kept since 1861, providing a measure of how conditions may have changed in recent years.
- 5Studies into the polar ice caps suggests that there has been a reduction in ice at both poles. Changes in the ice reflect the climatic changes occurring e.g. a loss of ice suggests increasing temperatures.Certain species rely on very specific conditions in order to survive, so by looking at changes in the distribution of species, scientists can determine how conditions might have changed. Similarly, new adaptations from animals indicates a need to adapt to changing environments.
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- A Levels Geography Karteikarten am Evidence for climate change, erstellt von caryyon am 18/02/2014.
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- caryyon · Feb 2014
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- 19 Feb 2016
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