California State University Long Beach 

Rapid climatic change

• Abrupt or shorter-lived than Milankovitch band cycles
• Related to switching on/off or changing the global conveyor belt
• Changes equator-pole heat flow
• Changes CO₂ reservoir
• I.e., Younger Dryas cold episode

• More than 2 dozen rapid warming events during last ice age (last 125,000 years)
• Previously unknown from marine sediment records
• Occur irregularly approximately every 1500-2000 years
• Discovered in the Greenland ice cores, and shown by:
• Oxygen isotopes (temperature)
• Up to 8-10°C in a few decades
• Dust (continental aridity and wind)
• Wetter when warm
• Snow (precipitation)
• Higher rates of accumulation
• CO₂ and Methane (CH₄)
• Greenhouse gases

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Heinrich events

• Huge iceberg armadas that covered the North Atlantic
• Recorded by 6 layers of ice-rafted sediment in deep sea ooze in the past Ice Age
• Occurred after about every 2-4 Dansgaard-Oeschger events
• During very cold intervals
• Approximately every 6100 years
• Finale of series of increasingly colder episodes
• In between the D-O warm events
• Sedimentation rates in the N. Atlantic are too low to record the more rapid D-O events

Rapid change in the Pacific Region

Santa Barbara basin

• Ultra-high-resolution sedimentary record
• Very high sedimentation rates (near land)
• Oceanographically & climatically sensitive location
• Combined record of land and sea environments
• Marine benthic organisms
• Land-derived pollen from plants
• Pines
• Oak/chapparral
• Minimal biological mixing
• Dansgaard-Oeschger interstadials
• Decreased oxygenation of bottom water
• Preservation of laminations
• Low-oxygen tolerant benthic foraminifera
• Surface water warmings
• Up to 7°C
• Also around the Pacific rim
• Japan Sea
• Offshore Oregon
• Gulf of California (Guaymas basin)
• Pacific circulation and environments influenced by global change
• Changed sources and character of intermediate water

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For any questions or problems with these pages contact>
John Francis
Email: jfrancis@csulb.edu
Phone: 562-985-4928
written by R. Behl.
Last changes: 24 Oct. 1997