A5030322151- Geology and Paleoclimatology Research
- Cryospheric studies and observations
- Climate variability and models
- Isotope Analysis in Ecology
- Archaeology and ancient environmental studies
- Methane Hydrates and Related Phenomena
- Tree-ring climate responses
- Atmospheric and Environmental Gas Dynamics
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Arctic and Antarctic ice dynamics
- Climate change and permafrost
- Landslides and related hazards
- Paleontology and Stratigraphy of Fossils
- Polar Research and Ecology
- Aeolian processes and effects
- Atmospheric chemistry and aerosols
- Pleistocene-Era Hominins and Archaeology
- Geological formations and processes
- Marine and coastal ecosystems
- Atmospheric aerosols and clouds
- Oceanographic and Atmospheric Processes
- Marine animal studies overview
- Geochemistry and Geologic Mapping
- Geomagnetism and Paleomagnetism Studies
University of Maine
2015-2024
Smithsonian Institution
2020
University of Maine System
2001
Yale University
1984-1993
Although the dramatic climate disruptions of last glacial period have received considerable attention, relatively little has been directed toward variability in Holocene (11,500 cal yr B.P. to present). Examination ?50 globally distributed paleoclimate records reveals as many six periods significant rapid change during time 9000"8000, 6000"5000, 4200"3800, 3500"2500, 1200"1000, and 600"150 Most events these are characterized by polar cooling, tropical aridity, major atmospheric circulation...
This paper reviews developments in our understanding of the state Antarctic and Southern Ocean climate its relation to global system over last few millennia. Climate this earlier periods has not been stable, as evidenced by occurrence abrupt changes atmospheric circulation temperature recorded ice core proxies for past climate. Two most prominent change events are characterized intensification circumpolar westerlies (also known Annular Mode) between ∼6000 5000 years ago since 1200–1000 ago....
Oscillations of Pinus (pine) pollen in a 50,000-year sequence from Lake Tulane, Florida, indicate that there were major vegetation shifts during the last glacial cycle. Episodes abundant populations climate was more wet than intervening phases dominated by Quercus (oak) and Ambrosia -type (ragweed marsh-elder). The episodes seem to be temporally correlated with North Atlantic Heinrich events, which massive, periodic advances ice streams eastern margin Laurentide Ice Sheet. Possible links...
For the tropical west coast of South America, where El Niño/Southern Oscillation (ENSO) is most pronounced, archaeological and associated paleontological deposits in northern Peru revealed a major climate change at about 5000 years before present (yr B.P.). The data implied presence stable, warm water as far south 10°S during early mid-Holocene (about 8000 to yr These suggest that ENSO did not occur for some millennia preceding B.P., when global regional was warmer than today.
Research Article| July 01, 2001 Variation in Holocene El Niño frequencies: Climate records and cultural consequences ancient Peru Daniel H. Sandweiss; Sandweiss 1Department of Anthropology Institute for Quaternary Studies, South Stevens Hall, University Maine, Orono, Maine 04469, USA Search other works by this author on: GSW Google Scholar Kirk A. Maasch; Maasch 2Department Geological Sciences Bryand Global Center, Richard L. Burger; Burger 3Peabody Museum Natural History Department...
Between about 8000 and 3000 years ago, climate worldwide underwent substantial changes. At the same time, human cultures experienced a period of progress toward more complex societies, as exemplified by first temple mounds in South America, Egyptian pyramids, rise fall civilizations East Asia. Archeologists paleoclimotologists alike are now investigating possible causal connections between these simultaneous developments finding pattern cultural responses to climatic change.
A previously formulated dynamical model of the late Pleistocene ice ages (based on hypothesis that global CO 2 system can provide instability to drive a natural oscillation involving feedbacks between cryosphere, atmosphere, and ocean) is extended include (1) additive earth orbital forcing (summer insolation changes at 65°N) (2) tectonic in form postulated variation multiplicative parameters (rate constants) system. The structural (e.g., bifurcation) properties are examined detail reveal...
A climatic feedback system previously described, consisting of three prognostic nonlinear equations governing the mass ice sheets ζ, marine and continental marginal χ, mean ocean temperature θ is forced by a representation effects external earth-orbital variations. With reasonable amplitudes for eccentricity, obliquity, precession forcing, free oscillatory solutions major period near 100 kyr can be modified in way that substantially agrees with δ18O-derived observations evolution. In...
A highly resolved Mt. Everest ice core reveals a decrease in marine and increase continental air masses related to relatively high summer surface pressure over Mongolia, reduction northward incursions of the South Asian monsoon since ∼1400 AD. Previously published proxy records from lower sites south Himalayas indicate strengthening this time. These regional differences are consistent with south–north seesaw convective activity region, reflect southward shift mean position trough The change...
A primary goal of the SCAR (Scientific Committee for Antarctic Research) initiated AntClim21 (Antarctic Climate in 21st Century) Scientific Research Programme is to develop analogs understanding past, present and future climates Southern Hemisphere. In this contribution we provide a framework achieving that includes: description basic climate parameters; comparison existing reanalyses; ice core sodium records as proxies frequencies marine air mass intrusion spanning past ∼2000 years. The...
Archaeological evidence plays a key role in longitudinal studies of humans and climate. Climate proxy data from Peruvian archaeological sites provide case study through insight into the history "flavors" or varieties El Niño (EN) events after ∼11 ka: eastern Pacific EN, La Niña, coastal EN (COA), central Modoki (CP). proxies are important to because more commonly used paleoclimate unavailable equivocal. Previously, multiproxy coast elsewhere suggested that frequency varied over Holocene: 1)...
ABSTRACT The theory of the Quaternary climate will be incomplete unless it is embedded in a more general for fuller Cenozoic that can accommodate onset ice-age fluctuations. Here we construct simple mathematical model late climatic changes based on hypothesis forced and free variations concentration atmospheric greenhouse gases (notably CO 2 ) coupled with global ocean state ice mass, under additional influence or earth-orbital forcing, are primary determinants over this long period. Our...
A dynamical model of the Pleistocene ice ages, incorporating many qualitative ideas advanced recently regarding possible role ocean circulation, chemistry, temperature, and productivity in regulating long‐term atmospheric carbon dioxide variations, has been constructed. This involves one additional term (and free parameter) beyond that included a previous (B. Saltzman A. Sutera, 1987), providing capacity for an asymmetic (for example, “saw‐toothed”) response. It is shown main features...
Abstract A 200‐year proxy for northerly air mass incursions (NAMI) into central and western West Antarctica is developed from the examination of 19 shallow (21–150 m deep) Antarctic ice‐core non‐sea‐salt (nss) Ca 2+ concentration records. The NAMI reveals a significant rise in recent decades. This unprecedented at least past 200 years coincident with anthropogenically driven changes other large‐scale Southern Hemisphere (SH) environmental phenomena such as greenhouse gas (GHG) induced...
ABSTRACT The abrupt climate shifts identified in Greenland ice cores transformed understanding of the system. Although primarily studied paleoclimate record, change induced by greenhouse gas rise poses a serious threat to modern humans and ecosystems. We present first ultra‐high‐resolution view (hundreds samples per year) onset (within 1 current interglacial (warm) retrieved from Ice Sheet Project Two (GISP2) core archive. This is manifested marked reduction storm event frequency increase...
Abstract Dust events originating from the Saharan desert have far‐reaching environmental impacts, but causal mechanism of magnitude and occurrence dust (SDEs) during preinstrumental era requires further research, particularly as a potential analog for future climate. Using an ultrahigh resolution glacio‐chemical record 2013 Colle Gnifetti ice core drilled in Swiss‐Italian Alps, we reconstructed 2000‐year‐long summer record. We analyzed both modern (1780–2006) premodern Common Era (CE) major...
Abstract Continuous, high‐resolution paleoclimate records from the North Pacific region spanning past 1500 years are rare; and behavior of Aleutian Low (ALow) pressure center, dominant climatological feature in Gulf Alaska, remains poorly constrained. Here we present a continuous, year long, calibrated proxy record for strength wintertime (December–March) ALow Mount Logan summit (PR Col; 5200 m asl) ice core soluble sodium time series. We show that concentrations statistically correlated...
Abstract Understanding past atmospheric dust variability is necessary to put modern into historical context and assess the impacts of on climate. In Asia, meteorological data temporally limited, beginning only in 1950s. High‐resolution ice cores provide ideal archive for reconstructing preinstrumental concentrations. Using a ~500 year (1477–1982 A.D.) annually resolved calcium (Ca) proxy from Tibetan Plateau (TP) core, we demonstrate lowest concentrations years during latter twentieth...
Abstract The Atlantic multidecadal oscillation (AMO) is a 60–70 year pattern of sea-surface temperature (SST) variability in the North commonly ascribed to internal ocean dynamics and changes northward heat transport. Recent modeling studies, however, suggest that SSTs fluctuate primarily response major volcanic eruptions atmospheric circulation. Here, we utilize historical SST, reanalysis, stratospheric aerosol optical depth data examine basic evidence supporting link. We find cool...