Is Dansgaard-Oeschger a global event?

Dansgaard-Oeschger event, also called D-O event, any of several dramatic but fleeting global climatic swings characterized by a period of abrupt warming followed by a period of slow cooling that occurred during the last ice age. This regular occurrence has led to the suggestion of a 1,500-year cycle of climate change.

What caused Dansgaard-Oeschger events?

The events may be caused by an amplification of solar forcings, or by a cause internal to the earth system – either a “binge-purge” cycle of ice sheets accumulating so much mass they become unstable, as postulated for Heinrich events, or an oscillation in deep ocean currents (Maslin et al.. 2001, p25).

How do we know that natural climate change has happened?

Scientists can track these earlier natural changes in climate by examining ice cores drilled from Greenland and Antarctica, which provide evidence about conditions as far back as 800,000 years ago. The ice cores have shown that rising CO2 levels and rising temperatures are closely linked.

What are Heinrich and Dansgaard-Oeschger events?

Scientists Willi Dansgaard and Hans Oeschger first reported the Dansgaard-Oeschger (D-O) events in Greenland ice cores. Each of the 25 observed D-O events consisted of an abrupt warming to near- interglacial conditions that occurred in a matter of decades and was followed by a gradual cooling.

How long are Dansgaard Oeschger events?

approximately 1460 years
Dansgaard–Oeschger cycles typically have a duration of approximately 1460 years, of which the last 600 years is represented by a distinct cold phase that ends abruptly with a pronounced change to warmer conditions.

When was the last Heinrich event?

Heinrich events are thought to be associated with sudden climate warming events that occurred between approximately 60,000 and 16,800 years ago during the most recent ice age of the Pleistocene Epoch (about 2.6 million to 11,700 years ago).

How long do Dansgaard Oeschger events last?

What happens to ocean circulation during a Heinrich event?

More specifically, D-O cold events, and their associated influx of meltwater, reduce the strength of the North Atlantic Deep Water current (NADW), weakening the northern-hemisphere circulation and therefore resulting in an increased transfer of heat polewards in the southern hemisphere.

How do Heinrich events occur?

Eventually, the accumulation of melting reaches a threshold, whereby it raises sea level enough to undercut the Laurentide Ice Sheet, thereby causing a Heinrich event and resetting the cycle. Hunt & Malin (1998) proposed that Heinrich events are caused by earthquakes triggered near the ice margin by rapid deglaciation.