Observing Climate - Proxy Data. Science Concepts Pollen analysis. Paleo Proxy Data (Con’t) Stable Isotope Analysis Palynology Midden Analysis Sedimentary Analysis. The Earth System (Kump, Kastin & Crane) • Chap. 15 (p. 292). The Earth System (Kump, Kastin & Crane) - PowerPoint PPT Presentation
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Climate and Global Change Notes
9-1
Observing Climate - Proxy Data
Paleo Proxy Data (Con’t)
Stable Isotope Analysis
Palynology
Midden Analysis
Sedimentary Analysis
Science Concepts
Pollen analysis
The Earth System (Kump, Kastin & Crane)
• Chap. 15 (p. 292)
The Earth System (Kump, Kastin & Crane)
• Chap. 15 (p. 292)
Climate and Global Change Notes
9-2
Stable Isotope Analysis
• 16O and 18O Isotope Analysis
- Oxygen isotope ratio (18O) is a measure of the ratio of heavy oxygen
(18O) to light oxygen (16O)
- Used as a proxy measure for paleotemperature
- More negative values indicate “colder” temperatures
• 12C/13C and 15N/14N Isotope Analysis
- “You are what you eat”, thus the building blocks that make your body,
have been taken from foods you have eaten over your lifetime.
- Specifically, the elements C and N in your bone are the same C and N
atoms that were in the foods you ate.
- Again we can measure the ratio of C isotopes and N isotopes to create
• Lennart von Post (1916) suggested that buried sediments of fossil pollen was
a precise method for determining past vegetation regimes and cycles of
vegetation change - Many plants produce great quantities of pollen or
spores that are dispersed by the wind
- Pollen and spores have very durable outer walls that can remain preserved
for thousands or even millions of years- Unique morphological features of each type of pollen
and spore remains consistent within each species, yet each different
species produces its own specific form
- Each pollen and spore-producing plant is restricted in its distribution by
environmental conditions that include moisture, temperature and soil type
- Most wind-dispersed pollen and spores rarely travel very far before falling
to the surface• Thus, by counting a sufficient number of fossil pollen and spores recovered
from each stratum in a deposit, one could reconstruct the types and abundance
of plants represented by those fossil grains
Observing Climate - Proxy Data
http://www.scirpus.ca/cap/articles/paper29.htm
Climate and Global Change Notes
9-10
Midden Analysis
• Middens are amalgamations of plant and animal remains encased in crystallized packrat urine
• First noted by military and scientific expeditions in the West as early as 1849
• During 1960s paleoecologists began to fully recognized potential for reconstructing past environmental change
• Packrats or woodrats gather and accumulate plant materials typically within 100 m of their den in dry caves and crevices
• Plant remains and other debris (including insect and vertebrate remains) are cemented into large massesof crystallized urine that can persevered for tens of thousands of years
• North Atlantic oceanic sediment cores are used to understand climatic variations during and since the last ice age but not just confined to local regions of the northeastern Atlantic
• Analyze cores by counting the number of both lithic (rock) and
plankton shell fragments
• Total number of particles fluctuate with climate changes
• Analysis of long cores indicate that plankton fragments dominated
(warm periods) for long stretches of time, while rock sediments
(cold periods) dominated in six spikes
• These sudden changes in sediments (referred to as Heinrich events; cold events) are also visible in X-rays of
sediment cores as sharp transitions between dark-colored (plankton-
dominated) and light-colored (lithic-dominated) segments
- Heinrich events: A significant SST drop occurs; reduces plankton fragments; extends the ice sheet onto the continental shelf; icebergs with lithic material breakoff; float off and melt depositing lithic
material over ocean bottom
- Non-Heinrich events: Deposited during warm periods with more plankton
material and fewer icebergs to transport lithic material