Observing Climate - Proxy Data

1. 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) • Chap. 15 (p. 292)

2. Observing Climate - Proxy Data 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 13C and 15N values similar to the 18O ratio above http://www.staff.brad.ac.uk/ mprichar/PRGIntrotoIsotopes.html

3. Observing Climate - Proxy Data Stable Isotope Analysis (Con’t) • 12C/13C and 15N/14N Isotope Analysis (Con’t) - 13C and 15N values of various foods are fairly well known - 13C and 15N values are signatures specific to different types of foods, - Measuring the 13C and 15N values of your bone, we can infer from what foods the bone C and N came - Why bone - its is best preserved over time - Analysis of the extracted protein portion of the bone, collagen, (and for radiocarbon dating) reflect the protein part of our diets - Adult collagen in our bones is constantly being replaced and completely turned-over in about 10 years

4. Observing Climate - Proxy Data Stable Isotope Analysis (Con’t) • 12C/13C and 15N/14N Isotope Analysis (Con’t) - 13C indicates how much marine protein (e.g., fish, shellfish) was in the diet, compared to terrestrial proteins (e.g., grains, breads, cattle meat and milk) - 15N indicates how much plant food was in the diet, compared to animal foods (like meat and milk) - Typical collagen isotope values Holocene Western Europe > 13C distinguishes between terrestrial (-20%) and marine (-12%) ecosystems > 15N of terrestrial herbivores are approximately 5%, terrestrial carnivores are at about 9% > For omnivores like humans the 15N indicates if they are behaving more like herbivores (plant protein) or carnivores (animal protein) http://www.staff.brad.ac.uk/mprichar/ PRGIntrotoIsotopes.html Terrestrial Ecosystems fish 15N carnivore shellfish herbivore Marine Ecosystems 13C

5. Observing Climate - Proxy Data http://www.ngdc.noaa.gov/paleo/slides/ slideset/15/15_292_slide.html Stable Isotope Analysis (Con’t) • Example - Ice Core Analysis - 18O (green line) and glacial ice accumulation (blue line) for 10,000- 17,400 y B.P. > Colder climate associated with lower accumulation values > Note how quickly the climate shifted from cold to warm phases during the glacial-interglacial transition > Research suggests that major climatic changes such as these may have occurred over just a few years, i.e., climate during the last glacial period was inherently unstable and subject to rapid fluctuations > The last 10,000 years have been the most consistent and stable climate in the 200,000 Greenland ice record > This same period appears to have been less stable at lower latitudes Periods of Rapid Change Accumulation (m ice / year) 18O Years Before Present

6. Observing Climate - Proxy Data http://www.ncdc.noaa.gov/paleo/slides/ slideset/20/20_409_slide.html Stable Isotope Analysis (Con’t) • Example - Ice Core Analysis (Con’t) - Quelccaya ice cap (5,670 m altitude; 164 m thick) provides clues about South American tropical climatic variability - Note Little Ice Age is identified in the 18O between 1550 and 1900 A.D.
 http://www.ncdc.noaa.gov/paleo/slides/slideset/20/20_400_slide.html

7. Observing Climate - Proxy Data Stable Isotope Analysis (Con’t) • Example - Coral Analysis - Ambient water conditions (i.e., Sea Surface Temperature (SST) and, possibly, fresh water influx and precipitation) when a layer of coral skeletons was deposited determine the 18O within ice cores). Thus, analyses of 18O can yield information about past water conditions - Note that red spikes (high 18O anomaly) in 18O correspond to the red spikes (high SST anomaly) in SST - Yellow zones indicate El Nino/ Southern Oscillation (ENSO) warm phases - Coral records can yield information 500-800 years into the past in many tropical areas http://www.ncdc.noaa.gov/paleo/slides/ slideset/13/13_240_slide.html SST Anomaly (°C) 18O Anomaly

8. Observing Climate - Proxy Data Palynology • Pronounced pal-ih-nol-o-jee, the "a" as in "map” • “Palyn” comes from a Greek word that means “I sprinkle” that is also a cognate of the Latin word “Pollen” which means dust or fine flour. • Branch of science dealing with microscopic (5 m to about 500 m), decay- resistant remains (such as pollen and spores, living and fossil) of certain plants and animals Figs. 1-8. Examples of pollen from flowering plants. Scale bar = 10 µm. Fig. 9. Pollen from a cone-bearing plant (e.g., pine). Scale bar = 10 µm. Reference Milne, L., 1998: Forensic Palynology. Pollen and spores, Nature's Fingerprints of Plants. http://science.uniserve.edu.au/faces/milne/milne.html

9. Observing Climate - Proxy Data Palynology (Con’t) • 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 http://www.scirpus.ca/cap/articles/paper29.htm

10. Observing Climate - Proxy Data http://www.ncdc.noaa.gov/paleo/slides/ slideset/16/16_307_slide.html 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 masses of crystallized urine that can persevered for tens of thousands of years Bushy-tailed woodrat http://www.ncdc.noaa.gov/ paleo/slides/slideset/16/ 16_308_slide.html

11. Observing Climate - Proxy Data http://www.ncdc.noaa.gov/paleo/slides/ slideset/16/16_313_slide.html Midden Analysis (Con’t) • Thus, midden materials represent the local environment when material was collected • Middens tend to be preserved in some environments better than others; arid climates good • Midden analysis locations

12. Observing Climate - Proxy Data http://www.ncdc.noaa.gov/paleo/slides/ slideset/16/16_316_slide.html Midden Analysis (Con’t) • Results for 89 Packrat Middens - Elevation zones for vegetation has shifted over the last 24,000+ years in the Grand Canyon

13. Observing Climate - Proxy Data Midden Analysis (Con’t) • Summary - Plants have shifted upward on the Colorado Plateau from last glacial period to the present - During the last glacial period, the timber line was lower than today - Also tree species have shifted upward http://www.ncdc.noaa.gov/paleo/slides/ slideset/16/16_320_slide.html

14. Observing Climate - Proxy Data Sediment Analysis • 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 http://earthobservatory.nasa.gov/Study/Paleoclimatology_SedimentCores/

15. Observing Climate - Proxy Data http://www.ncdc.noaa.gov/paleo/slides/slideset/19/19_380_slide.html Sediment Analysis • What could cause these different sediments? - 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