Can Ice Sheets Trigger Abrupt Climatic Change?

1996 ◽  
Vol 28 (4) ◽  
pp. 448 ◽  
Author(s):  
T. Hughes
Keyword(s):  
Climatic Change ◽  
Ice Sheets ◽  
Abrupt Climatic Change

Quaternary Climatic Changes and Landscape Evolution

2005 ◽  
Author(s):  
Jürgen Ehlers
Keyword(s):  
Climatic Change ◽  
Large Scale ◽  
Western Europe ◽  
Ice Sheets ◽  
Climatic Changes ◽  
Mountain Glaciers ◽  
Marine Deposits ◽  
The North ◽  
Terrestrial Sediments ◽  
International Geological Congress

The last 2–3 Ma have witnessed climatic changes of a scale unknown to the preceding 300 Ma. In the cold periods vegetation was reduced to a steppe, giving rise to large-scale aeolian deposition of sand and loess and river sands and gravels. In the warm stages, flora and fauna recolonized the region. Parts of Europe were repeatedly covered by mountain glaciers or continental ice sheets which brought along huge amounts of unweathered rock debris from their source areas. The ice sheets dammed rivers and redirected drainage towards the North Sea. They created a new, glacial landscape. This chapter presents an outline of the climatic history, and in particular the glacial processes involved in shaping the landscapes of western Europe. By convention, geologists generally tend to draw stratigraphical boundaries in marine deposits because they are more likely to represent continuous sedimentation and relatively consistent environments in comparison to terrestrial sediments. However, marine deposits from the period in question are relatively rarely exposed at the surface. According to a conclusion of the International Geological Congress 1948 the Tertiary/Quaternary boundary was defined as the base of the marine deposits of the Calabrian in southern Italy. In the Calabrian sediments fossils are found that reflect a very distinct climatic cooling (amongst others the foraminifer Hyalinea baltica). This climatic change roughly coincides with a reversal of the earth’s magnetic field; it is situated at the upper boundary of what is called the Olduvai Event. Consequently, it is relatively easy to identify; its age is today estimated at 1.77 Ma (Shackleton et al. 1990). However, in contrast to the older parts of the earth’s history, the significant changes within the Quaternary are not changes in faunal composition but changes in climate. For reasons of long-term climatic evolution the base of the Calabrian is not a very suitable global boundary. Its adoption excludes some of the major glaciations from the Quaternary. Therefore, in major parts of Europe another Tertiary/Quaternary boundary is in use, based on the stratigraphy of the Lower Rhine area (e.g. Zagwijn 1989). Here the most significant climatic change is already recorded as far back as the Gauss/Matuyama magnetic reversal (some 2.6 Ma ago).

Home sapiensorCastor fiber?

Antiquity ◽  
1983 ◽  
Vol 57 (220) ◽  
pp. 95-102 ◽  
Author(s):  
J. M. Coles ◽  
B. J. Orme
Keyword(s):  
Climatic Change ◽  
Pollen Analysis ◽  
Ice Sheets ◽  
Change Rate ◽  
Species Migration ◽  
Atlantic Period ◽  
Vegetational Change ◽  
Vegetational Succession ◽  
Glacial Refuges

Following the development of pollen analysis in the earlier part of this century, much effort was devoted to unravelling the sequence of vegetational change during and after the retreat of the last European ice-sheets. The outlines established, questions of causation came to the fore, and the debate focused on factors such as climatic change, rate of species migration from glacial refuges, and natural vegetational succession. In more recent decades, a further factor has been widely investigated, namely the possible influence of humans on the landscape, principally as farmers and smiths. The development and modification of hypotheses is well illustrated by the Elm Decline of the Atlantic period, where climate (Iversen, 1941) or man (Troels-Smith, 1960) and occasionally disease (see refs in Simmons & Tooley, 1981, 134) have been held responsible for a widespread but by no means straightforward decline in elm pollen.

Evidence for abrupt climatic change in northern Scotland between 3900 and 3500 calendar years BP

The Holocene ◽  
1998 ◽  
Vol 8 (1) ◽  
pp. 97-103 ◽  
Author(s):  
David E. Anderson ◽  
Heather A. Binney ◽  
Melanie A. Smith
Keyword(s):  
Climatic Change ◽  
Abrupt Climatic Change

Younger Dryas research and its implications for understanding abrupt climatic change

1997 ◽  
Vol 21 (2) ◽  
pp. 230-249 ◽  
Author(s):  
David E. Anderson
Keyword(s):  
Climatic Change ◽  
North Atlantic ◽  
Large Scale ◽  
Thermohaline Circulation ◽  
Younger Dryas ◽  
Theoretical Understanding ◽  
The North ◽  
Consequent Reduction ◽  
The North Atlantic ◽  
Abrupt Climatic Change

The Younger Dryas refers to the final phase of cold, glacial conditions preceding the abrupt climatic warming at the beginning of the Holocene. The existence of the Younger Dryas in Europe has been known for most of this century, although recent research suggests that the Younger Dryas cooling may have been global. Estimates of the timing of the event have also improved in recent years, showing that both the onset and termination of the Younger Dryas were abrupt, occurring within decades. The Younger Dryas has been linked with a large-scale shift of the North Atlantic thermohaline circulation (THC) to a near glacial mode with a consequent reduction in northward heat transport. This shift in the THC may have been triggered by a discharge of Laurentide ice, combined with meltwater inputs from several locations around the North Atlantic. Further study of the events leading up to the Younger Dryas is necessary for improving theoretical understanding of abrupt climatic change, and for evaluating GCM models which seek to simulate the response of the THC to freshwater forcing. With predicted increases in freshwater input to the North Atlantic resulting from increases in atmospheric CO2, a future shift in the THC is a possibility. Predicting the magnitude and climatic consequences of such an event depends upon further study of the Younger Dryas and of other abrupt palaeoclimatic changes which involved the THC.

Ice Sheets and Sea Level Change as a Response to Climatic Change at the Astronomical Time Scale

1990 ◽  
pp. 85-107 ◽  
Author(s):  
A. Berger ◽  
TH. Fichefet ◽  
H. Gallee ◽  
I. Marsiat ◽  
CH. Tricot ◽  
...  
Keyword(s):  
Climatic Change ◽  
Sea Level ◽  
Time Scale ◽  
Ice Sheets ◽  
Sea Level Change ◽  
Level Change ◽  
Astronomical Time ◽  
And Sea Level
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