Paleoclimate
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Geology (main)
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Climate Study Project[1]
Paleoclimate is the circumstance of much earlier mean meteorological conditions, for times prior to instrumental weather measurements. Most discussions of paleoclimate relate to prehistoric times, where written records of meteorology are n,ot extant. Paleo-climatologists use information from natural climate proxies, such as tree rings, ice cores, stalagmites, corals, and ocean (Seas of the world) and lake sediments, that record variations in past climate.
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 (Groups Article) 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.
Contents
Drought
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Typhoon and Hurricane Frequency
On a decadal average, the twenty-year interval from 1660 to 1680 AD is the most intense typhoon period of record, with 28 to 37 typhoon landfalls per decade. The variability in typhoon landfalls in Guangdong parallels observations in other Asian paleoclimatic proxies (such as tree rings, ice cores). Notably, the two periods of highest typhoon landfalls in Guangdong (AD 1660-1680, 1850-1880) coincide with two of the coldest periods in China during the Little Ice Age. Thus, as in the case of hurricanes, there is no correlation of typhoon activity with industrialization, combustion of fossil fuels, global warming or greenhouse gases. In fact, highest typhoon frequency occurred in the coldest century of the last millennium.(Liu et al, 2003)
In North America, distinct sand layers survive in the nearshore sediments of Alabama's Lake Shelby as a result of storm-tide overwash of beaches and dunes. Sediment cores from the lake center hold multiple sand layers, suggesting that major hurricanes of category 4 or 5 intensity directly struck the coast at circa 3.2-3.0, 2.6, 2.2, 1.4, and 0.8 ka (14C year), with an average recurrence interval of approximately 600 years. There is no evidence to suggest prehistoric or historic hurricane frequencies have altered during the Holocene. (Liu & Mirriam, 1993)
Temperature
Polar sea mean temperature vs time (millions of years before present). Note: Only leftmost x-axis numbers in millions. Source: Robert A. Rohde
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 since 1870, after taking account of the overestimate of terrestrial warming due to the urban heat island effect.
See also
- Coral reef
- Global Cooling
- Holocene Climate
- Human History and Earth Temperature
- Isostatic Rebound
- Eemian
- Little Ice Age
- Shetland Islands, Scotland
- Sea Level
- The Cenozoic Era: Climate in the last 65 Million Years
References
- K. R. Briffa, P. D. Jones, T. S. Bartholin, D. Eckstein, F. H. Schweingruber, W. Karlén, P. Zetterberg, M. Eronen, Fennoscandian summers from A.D. 500: Temperature changes on short and long timescales. Clim. Dyn. 7, 111–119 (1992).
- U. Büntgen, W. Tegel, K. Nicolussi, M. McCormick, D. Frank, V. Trouet, J. O. Kaplan, F. Herzig, K.-U. Heussner, H. Wanner, J. Luterbacher, J. Esper, 2500 years of European climate variability and human susceptibility. Science 331, 578–582 (2011).
- Ed Cook. (2001) North American Drought Atlas. National Science Foundation, Division of Atmospheric Sciences, Paleoclimate Program, SGER Award ATM 03-22403
- R. J. Cooper, T. M. Melvin, I. Tyers, R. J. S. Wilson, K. R. Briffa, A tree-ring reconstruction of East Anglian (UK) hydroclimate variability over the last millennium. Clim. Dyn. 40, 1019–1039 (2013).wkins, E., and R. Sutton (2009) The potential to narrow uncertainty in regional climate predictions. Bull. Amer. Meteor. Soc., 90, 1095–1107
- Kam-biu Liu; Miriam L. Fearn (1993) Lake-sediment record of late Holocene hurricane activities from coastal Alabama. Geology (1993) 21 (9): 793–796. https://doi.org/10.1130/0091-7613(1993)021<0793:LSROLH>2.3.CO;2
- Kam-biu Liu, Caiming Shen and Kin-sheun Louie (2001) A 1,000-Year History of Typhoon Landfalls in Guangdong, Southern China, Reconstructed from Chinese Historical Documentary Records. Annals of the Association of American Geographe
- Malcolm K Hughes & Peter M Brown (1992) Drought frequency in central California since 101 B.C. recorded in giant sequoia tree rings. Climate Dynamics volume 6.
- Mann, Michael E.; Zhang, Zhihua; Hughes, Malcolm K.; Bradley, Raymond S.; Miller, Sonya K.; Rutherford, Scott; Ni, Fenbiao (9 September 2008), "Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia", Proceedings of the National Academy of Sciences of the United States of America, 105 (36): 13252–13257, Bibcode:2008PNAS..10513252M,
- Nangombe, Shingirai, Madyiwa, Simon, Wang, Jianhong, (2018) Precursor conditions related to Zimbabwe's summer droughts. Theoretical and Applied Climatology, Volume 131, Issue 1-2, pp. 413-431
- Jennings, Jesse (1957). Danger Cave. Salt Lake City: University of Utah Press Anthropological Papers, No. 27. ISBN 978-0874806120
- 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.
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