Holocene
The Holocene is the name given to the recent 10,000 to 12,000 years of the Earth's history -- the time since the end of the last major glacial advance. and also the end of the last major global cooling epoch.
Since then, there have been small-scale climate shifts -- notably the Little Ice Age between about 1200 and 1700 A.D. The chief climate trend of the Holocene has been a warming period interspersed with minor Ice ages. However the Holocene itself can be regarded as a warming period of the previous Ice Age that began in the Pleistocene (the period beginning about two-and-a-half million years ago and lasting until the beginning of the Holocene).
Another name for the Holocene that is sometimes used is the Anthropocene, the Age of Man. This term may be somewhat misleading: humans of our own subspecies, Homo sapiens sapiens, had appeared and dispersed over most of the world well before the start of the Holocene. Yet the Holocene has witnessed the human population explosion and all of humanity's recorded history and the rise and fall of all its civilizations.
Humanity has greatly influenced the Holocene environment; while all organisms influence their environments to some degree, none have changed the globe as much, or as rapidly, as our species is doing. Many scientists argue that human activity is at least partially responsible for global warming, an increase in mean global temperatures; however, most atmospheric scientists assert the fundamental contributions of man to modern climate change began at several millennia ago, with broad scale deforestation and resultant carbon releases to the atmosphere (Earth's atmosphere).
Habitat destruction, habitat fragmentation, pollution, and other factors are causing an ongoing mass extinction of plant and animal species; according to some projections, 20% of all plant and animal species on Earth will become extinct within the next 25 years.
Yet the Holocene has also seen the great development of human knowledge and technology, which can be used -- and are being used -- to understand the changes that are occurring, to predict their effects, and to mitigate the damage they may do to the Earth and to us. Paleontologists are part of this effort to understand global change. Since many Fossils provide data on climates and environments of the past, paleontologists are contributing to our understanding of how future environmental change will affect the Earth's life.
Climate and Geology
While the time extent of the Holocene has not allowed for major tectonic movements or mountain uplift, the change in sea levels from net glacial melting has altered the lacustrine and coastal marine landform environment appreciably. For example, the formation of the Irish Sea and Baltic Sea, as well as the enlargement of the North Sea and Hudson Bay are products of Holocene sea level rise combined with post-glacial isostatic rebound.
The warming and glacial melt associated with the Holocene actually began early in the epoch. For example, the Norwegian Sea gyre pattern not only broke down abrubtly in the early Holocene (which began about 12,000 years before the present) with massive melting of Arctic ice, but the Holocene pattern appears to have shifted even within the last five thousand years, by examining Bischof's ice raft analysis. These Holocene vacillations in current pattern augur for the notion that man's impact on climate began thousands of years ago, probably with the massive deforestation and accompanying grazing (including considerable overgrazing) that accompanied his rise to planetary dominance beginning in the early Holocene.
However, it is notable that the warmest periods in human history were the Roman Warm Period and the Medieval Warm Period, both of which were warmer than the early 21st century AD; this is particularly notable since those early warm periods were lacking in greenhouse gases sometimes associated with global warming.
The climate of the Holocene resembles that of the Eemian epoch which was the prior interglacial era.
Human Dominance
A rapid population explosion of Homo sapiens began with the onset of the Holocene, when milder temperatures enabled the human species to expand his geographic range. More significantly the early Holocene marked a period of transition between man's status as a hunter-gatherer to his status as a farmer. The transition to sedentary agriculture allowed further amplification of the population of H. sapiens, but also occassioned the disruption of ecological systems throughout the world; in fact, clearing features of the natural environment for food production has likely comprised the largest suite of habitat destruction activity in the Holocene.
Wildfires
The early Holocene was a time of higher Wildfire frequency and intensity, baed upon proxy records.
See Also
- Dark Ages
- Eemian
- Edenic period
- Isostatic Rebound
- Minoan Warm Period
- Paleoclimate
- Sea Level
- Water Wastage
References
- Jens Bischof. 2000. Ice drift, ocean circulation, and climate change. (Google eBook). Springer. 215 pages
- The Holocene Journal
- University of California Museum of Paleontology Homepage
- E.O. Wilson. 2005. The Future of Life. Alfred A. Knopf. New York, New York, USA
Part of this article content was provided by Ben Waggoner for University of California Museum of Paleontology.
