Weather & Climate

Paleoclimate

April 4, 2013, 2:58 pm
Source: NOAA
Content Cover Image

Polar sea mean temperature vs time (millions of years before present). Source: Robert A.Rohde

Paleoclimate is the circumstance of much earlier mean meterological condtions, for times prior to instrumental weather measurements. Most discussions of paleoclimate relate to prehistoric times, where written records of meteorology are not extant. Paleoclimatologists use information from natural climate proxies, such as tree rings, ice cores, corals, and ocean and lake sediments, that record variations in past climate.

This article is written at a definitional level only. Authors wishing to improve this entry are inivited to expand the present treatment, which additions will be peer reviewed prior to publication of any expansion.

Records of past climate from these proxy records are important for several reasons. Instrumental records of climate are limited in many parts of the world to the past 100 years or less, and are too short to assess whether climate variability, events, and trends of the 20th and 21st centuries are representative of the long-term natural variability of past centuries and millennia. For example, was the 1930s Dust Bowl drought, a widespread and severe event in the United States, a rare occurrence or have similar events occurred in past centuries?

Knowledge of the long-term natural variability of the Earth Climate system, and its causes, will also allow an understanding of the roles of natural climate variability and human-induced climate change in the current and future climate. In particular, reconstructed temperatures from proxy data for the past 1000 years have allowed an assessment of the warming over recent decades and indicate that at least part of this warming is due to the impact of human activities on climate, according to the Intergovernmental Panel on Climate Change.

Geological evidence demonstrates that the Earth's climate is dynamic, and has varied widely from our everyday experience. Over the past two million years, numerous glacial periods have covered much of the northern hemisphere in glacial ice, dropped sea level as much as 125 meters, and significantly cooled even tropical regions. In the more distant past, the Cretaceous Period was significantly warmer than today, with less polar ice, raising sea levels and allowing warm weather organisms to thrive at higher latitudes than previous. In the past 150 years, instrumental weather records indicate that the Earth has warmed by approximately 0.6°C.

See also

References

  • J.Halfar, R.S.Steneck, M.Joachimski, A.Kronz and A.D.Wanamaker (2008). Coralline red algae as high-resolution climate recorders. Geology 36: 463.
  • International Partnerships in Ice Core Sciences (2011) The oldest ice core: A 1.5 million year record of climate and greenhouse gases from Antarctica.
  • Milutin Milankovitch  [1941] (1998). Canon of Insolation and the Ice Age Problem. Belgrade: Zavod za Udz?benike i Nastavna Sredstva. ISBN 8617066199.
  • S.Sahney and M.J.Benton (2008). Recovery from the most profound mass extinction of all time. Proceedings of the Royal Society: Biological 275 (1636): 759–65.
  • J. Schopf (1983). Earth’s Earliest Biosphere: Its Origin and Evolution. Princeton NJ: Princeton University Press. ISBN 0691083231.
  • J.Veizer (2005). Celestial climate driver: a perspective from four billion years of the carbon cycle. Geoscience Canada
  • Veizer (1976). Windley, B.F.. ed. The Early History of the Earth. London: John Wiley and Sons
  • Gabrielle Walker (2004). Palaeoclimate: Frozen time. Nature (429): 596-597.
  • B.Windley (1984). The Evolving Continents. New York: Wiley Press. ISBN 0471903760.
Glossary

Citation

Syste, N. (2013). Paleoclimate. Retrieved from http://www.eoearth.org/view/article/155121

0 Comments

To add a comment, please Log In.