Lecture 8 Flashcards
Quaternary
Quaternary
2.58ma - present
Mostly Pleistocene & 11.7ka holocene
- large scale glaciation of N hemi
- icehouse
importance of early Pleistocene periodical glaciations
marks gradual change from obliquity to eccentricity dominated cycling
- stronger, longer and less frequent glacial/interglacials
human evolution began around
2.5mya
LGM ended when
12ka, brought in holocene
marine isotope stages
record of repeated galc/interglac goiong back to pleiocene
- core samples
- like a thermometer and ice mass-ometer
warm periods are assigned ___ numbers, and cold are ___
odd, even
we are in 1 right now
104 total
8 major ones marked with roman numerals (terminations)
milankovitch cycles can push us into a steady state by
coinciding with a peak in insolation and timing of a temrination, paired with an amplifier
amplifiers occur when
cooling/warming is initiated
ice albedo feedback
amplifier
- positive feedback
- very important
vegetation albedo feedback
amplifier
- positive feedback
- interglacials have more forests and more ocean so lower albedo
- glacials have ice and lower sea level so higher albedo
carbon is sequestered during ____ and liberated during ____
glacials, interglacials
Iron fertilization
shelf-nutrient hypothesis
- iron in dust blows into ocean, glacial cooling, more wind/arid/exposed sea floor, more dust, more biologic production, CO2 sequestered into CaCO3 limestone, more cooling
during glacials ocean is a carbon ____
sink (iron fertilization and cold water is more co2 soluble), source in interglacials (upwelling from thermal gradient)
Dust during glacial times
drier, colder, increased number of dust sources, reduced washout , greater wind intensities
effects of increased dust
- more reflective/higher albedo
- negative feedback of snow and ice albedo
- indirect effect of clouds (nucleation, coverage)
- iron fertilization
- overall intensifictaion of glacials
