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Climate Change The Evidence (Ice and Sediment Cores (ice sheets are made…
Climate Change
The Evidence
The Quaternary Period is the most recent geological time period, Spanning from about 2.6 million years ago to the present day.
In the period before the Quaternary, the earths climate was warmer and quite stable. then things changed a lot.
During the Quaternary, global temperature has shifted between cold glacial periods that last for around 100000 years, and warmer inter-glacial periods that last for around 10000 years.
The last glacial period ended around 15000 years ago. since then the climate has been warming.
Global Warming is the term used to describe the sharp rise in global temperatures over the last century. Its a types of climate change.
Ice and Sediment Cores
ice sheets are made up of layers of ice, one layer for each year.
Scientists drill into ice sheets to get long cores of ice.
By analyzing the gases trapped in the layers of ice, they can tell what the temperature was that years.
One ice core from Antarctica shows the temperature changes over 400 000 years.
The remains or organism found in cores taken from ocean sediment can also be analysed.
Temperature Records
Since the 1850s global temperatures have been measured accurately using thermometers.
Historical records can extend the records of climate changes a bit further.
Pollen Analysis
Pollen from plants gets preserved in sediment.
Scientists can identify and date the preserved pollon to show which spices were living at the time.
Tree rings
As a tree grows it forms rings for a new years and depending on how big the rings are it can tell us how much rainfall or how warm it was that years and it can also tell us how old the tree is by the amount of rings it has.