Planet Earth and Its Environment
Paleoclimatology is the study of prehistoric climates from evidence preserved in a wide range of geological settings. Paleoclimatologists study the evidence preserved in these geological settings, and search for the reasons behind climatic change throughout Earth’s history. By doing this, scientists may better predict future climate change and calculate the impact of humankind’s activities on the atmosphere and climate. Paleoclimatologists must piece together climatic history, but the further they look into the past, the more evidence has faded due to erosion and chemical processes. Scientists have been able to put together a detailed picture of the last 20, 000 years of climatic history, and a general picture of the past 150,000. Although the evidence is less complete further back in time, scientists have been able to identify major, often catastrophic climatic events throughout Earth’s 4.5 billion year history.
Evidence for climate change can be preserved in marine and lake sediments, ice sheets, fossil corals, glacial deposits, sedimentary structures, fossils and ice cores. Advances in laboratory techniques have allowed scientists to show how and why the climate has changed in the past.
Marine Sediments
The accumulated remains of marine organisms make much of the deep ocean floor. When these organisms were alive, they would absorb oxygen from the sea water. Scientists can deduce the past ocean temperatures, and therefore global climate by careful analysis of the oxygen in these organic sediments.
Studies have shown that oceanic sediments have preserved a record reaching back tens of millions of years, and in older sedimentary rocks the record extends to hundreds of millions of years.
Ice Cores
Scientists can directly analyse gases in ice cores from ancient atmospheres. Traces of the ancient atmospheres become trapped and compressed into the ice and the ice retains it there for as long as it remains frozen. Cores drilled through ice sheets contain a
Evidence for climate change can be preserved in marine and lake sediments, ice sheets, fossil corals, glacial deposits, sedimentary structures, fossils and ice cores. Advances in laboratory techniques have allowed scientists to show how and why the climate has changed in the past.
Marine Sediments
The accumulated remains of marine organisms make much of the deep ocean floor. When these organisms were alive, they would absorb oxygen from the sea water. Scientists can deduce the past ocean temperatures, and therefore global climate by careful analysis of the oxygen in these organic sediments.
Studies have shown that oceanic sediments have preserved a record reaching back tens of millions of years, and in older sedimentary rocks the record extends to hundreds of millions of years.
Ice Cores
Scientists can directly analyse gases in ice cores from ancient atmospheres. Traces of the ancient atmospheres become trapped and compressed into the ice and the ice retains it there for as long as it remains frozen. Cores drilled through ice sheets contain a
Bibliography: Nasif Nahle. 2007. Cycles of Global Climate Change. Biology Cabinet Journal Online. Article no. 295. http://www.biocab.org/Climate_Geologic_Timescale.html, and http://www.biocab.org/Carbon_Dioxide_Geological_Timescale.html. Accessed: (8th, March, 2011) David Heffernan. Rob Mahon. John McDougall. Kylie Gillies. 2009. Spotlight Earth and Environmental Science 1. Science Press: NSW Australia Accessed: (7th, March, 2011) http://CO2now.org and http://www.theclimatechangeclearinghouse.org and http://earthguide.ucsd.edu/virtualmuseum/climatechange2/ Accessed: (7th, March, 2011)