Maloof Home

Adam Maloof
Assistant Professor of Geosciences (Geology)

Department of Geosciences
213 Guyot Hall
Princeton University
Princeton, NJ 08544

Phone: (609) 258-2844
E-Mail: maloof@princeton.edu

Throughout the Phanerozoic (the past 543 million years), the Earth has alternated between two different modes of climate: Hothouse conditions and Icehouse conditions. Hothouse conditions are characterized by the absence or near-absence of polar ice, while in Icehouse times the Earth has stable polar ice sheets and consequently larger astronomically-driven climatic variability. The Earth is currently in the midst of an interglacial period of an Icehouse world. The most recent Hothouse period lasted from the Triassic through the Eocene, with permanent Antarctic ice sheets being established by the beginning of the Oligocene, about 35 million years ago.

Multiple proxies indicate that carbon dioxide levels during the warm early Eocene (about 55 million years ago) exceeded 900 ppm, with levels falling below twice the pre-industrial level in the late Eocene to middle Oligocene (about 30 million years ago) and attaining near pre-industrial levels in the late Oligocene to early Miocene (about 25 million years ago). For perhaps the first time since the Oligocene, atmospheric carbon dioxide levels will likely exceed twice the preindustrial levels by the middle of the current century. Under scenario A1FI of the Intergovernmental Panel on Climate Change (IPCC), the "business-as-usual" scenario, Eocene levels will be reached around the end of the century, which provides a strong motivation for developing a high temporal resolution record of the early Cenozoic Hothouse.

Moreover, the early Eocene includes several intervals in which carbon isotopes and carbonate dissolution horizons indicate the injection into the atmosphere of large amounts of carbon dioxide or methane over a period of less than about thirty thousand years, followed by a recovery period that lasted about one hundred to two hundred thousand years. Oxygen isotopes indicate temperature rises associated with these events of about 3-8 C. These "hyperthermal" events -- the Paleocene/Eocene Thermal Maximum (PETM) at about 55.5 million years ago and a few smaller events over the subsequent three million years -- provide analogs for the modern human experiment with increasing atmospheric greenhouse gases.

The early-to-middle Eocene Okanagan Highlands of British Columbia have provided a rich Eocene continental fossil record that has been studied for 130 years, but studies focused on other aspects of Okanagan sedimentary deposits have been scarce. Characteristic of the Okanagan are a suite of small, fault-bounded basins in which fossiliferous lacustrine sediments were often deposited during periods of volcanic inactivity.

In at least two localities, Horsefly and McAbee, diatomaceous shales preserve annual sub-millimeter varves for continuous lengths of up to several meters, representing as much as 10,000 years. These varved beds are of particular interest because they may preserve a time capsule of short-term environmental variability comparable to those extractable from Quaternary lacustrine sediments. In addition, as continental records, lacustrine deposits preserve a more direct signal of atmospheric conditions than do marine sediments. Palynological and paleontological studies, as well as a small number of U-Pb zircon ages, indicate that the Okanagan sediments were deposited between approximately 52 and 49 million years ago and might therefore record the last of the hyperthermal events. Using U-Pb analysis to date ashes and provide a temporal context for our studies, we are employing environmental magnetic and geochemical analyses, including studies of carbon isotopes, elemental composition, and ferromagnetic resonance, to extract paleoclimatic signals from the Okanagan sediments. -- Bob Kopp