Tree Rings: The growth of a tree is influenced significantly by climate. Tree ring widths, density of the trees, and isotopic composition are a reflection on the climate a tree is in. For example in a balmy climate a tree usually produces only one ring a year thus providing a record of climatic conditions each given year. Trees can grow to be hundreds or even thousands of years old and hold records of climate for centuries to millennia. The webpage, compiled by Henri D.
Grissino-Mayer of the University of Tennessee at Knoxville, focuses on the science of Dendochronology carbon dating of remains. Ice Cores: Ice is located in polar ice caps and high in mountains and has accumulated due to snowfall over many millions of years.
Climatologists dig through the ice with drills to collect ice cores. These cores contain many things such as dust, air bubbles and oxygen isotopes. Expert scan use what they have collected to determine the past climate of an area. Ocean and Lake Sediments: There are billions of tons of sediments that gather in lakes and oceans each and every year.
The carbonate also contains isotopes of oxygen as well as trace metals that can be used to determine the temperature of the water in which the coral grew. Scientists can then use this information to reconstruct the climate when the coral lived. All flowering plants produce pollen grains , which are another type of proxy data. Scientists can use the distinctive shapes of pollen grains to identify the type of plant from which they came.
Since pollen grains are well preserved in the sediment layers in the bottom of a pond, lake, or ocean, an analysis of the pollen grains in each layer tells scientists what kinds of plants were growing at the time the sediment was deposited. Scientists can then make inferences about the climate of the area based on the types of plants found in each layer.
Located high in the mountains and near the poles, ice —another type of proxy data—has accumulated from snowfall over many millennia. Scientists drill through the deep ice to collect ice cores, which often have distinct layers in them.
These layers contain dust, air bubbles, or isotopes of oxygen, differing from year to year based on the surrounding environment, that can be used to interpret the past climate of an area. Ice cores can tell scientists about temperature, precipitation, atmospheric composition, volcanic activity, and even wind patterns. Trees and their unique rings also serve as proxy data. Because climate conditions influence tree growth, patterns in tree-ring widths, density, and isotopic composition reflect variations in climate.
In temperate regions where there is a distinct growing season, trees generally produce one ring a year, recording the climate conditions each year. Trees can also grow to be hundreds to thousands of years old and can contain annual records of climate for centuries to millennia. Caves and the unique rock formations inside them also serve as proxy data.
Because the amount of water making its way into caves determines the amount speleothems grow, their layers can indicate times of both heavy precipitation and drought. Plant-rich deposits called pack rat middens are another type of proxy data. Learn more in: Dendrochronology and Climate Change. Find more terms and definitions using our Dictionary Search.
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