Maureen E. Raymo | |
---|---|
Born | |
Alma mater |
|
Awards | Wollaston Medal, Milutin Milankovic Medal, Maurice Ewing Medal |
Scientific career | |
Fields | Climate Scientist and Marine Geologist |
Institutions |
Maureen E. Raymo (born 1959) is an American paleoclimatologist and marine geologist. She is the Co-Founding Dean Emerita of the Columbia Climate School [1] and the G. Unger Vetlesen Professor of Earth & Environmental Sciences at Columbia University. From 2011 to 2022, she was also Director of Lamont-Doherty Earth Observatory's (LDEO) Core Repository and, until 2024, was the Founding Director of the LDEO Hudson River Field Station. [2] From 2020 to 2023, she was first Interim Director then Director of Lamont-Doherty Earth Observatory, the first climate scientist and first female scientist to head the institution. [3]
Raymo has done pioneering work on the origin of the ice ages, the geologic temperature record of the Earth, and past sea level change, publishing over 100 peer-reviewed scientific articles. Her work underlies fundamental ideas in paleoceanography including the uplift weathering hypothesis, the "41,000-year problem," the Pliocene sea-level paradox, and the Lisiecki-Raymo δ18O stack. [4] [5] [6] [7]
In 2014, Raymo became the first woman to win the Wollaston Medal for geology, which had been awarded for 183 years at the time. She was described in her nomination as "one of the foremost and influential figures in the last 30 years." [8]
Raymo was born in Los Angeles, [9] and at the age of eight she sailed with her family to Europe on the ocean liner S.S. United States and resolved to dedicate her life to studying the ocean. The books and films of Jacques Cousteau were also important early influences. [10] Raymo attended Oliver Ames High School in Easton, Massachusetts, where she graduated with the Bausch and Lomb Honorary Science Award, and then attended Brown University, receiving her Sc.B. Geology in 1982. After a brief stint working in a lab, she then attended Columbia University, where she earned her M.A. in geological sciences in 1985, her M.Phil. in geology in 1988, and her Ph.D. in geology in 1989. [9]
Raymo is known for developing (along with William Ruddiman and Philip Froelich) the Uplift-Weathering Hypothesis. [11] [12] According to this hypothesis, tectonic uplift of areas such as the Himalayas and Tibetan plateau over the last 40 million years contributed to surface cooling and thus the Ice Ages. Mountain uplift enhances the chemical weathering of minerals, a process that removes carbon dioxide from the atmosphere. The resulting cooling led to the growth of large ice sheets at both poles. Raymo and her colleagues initially suggested that measuring the proportions of isotopes of strontium (Sr) in deep ocean sediments could substantiate the Uplift-Weathering Hypothesis but soon recognized that ambiguities in the sources of strontium to the ocean existed. Over 35 years later, the hypothesis continues to be debated and studied with many new lines of evidence proposed. [13] [14] [15] [16] Their proposed mechanism of CO2 removal, the chemical weathering of mechanically crushed rock, is also the scientific basis behind projects which aim to remove anthropogenic CO2 from the atmosphere via artificially enhanced chemical weathering. [17]
Raymo is known for her research using sedimentological and geochemical data from deep sea cores to better understand how the ocean's thermohaline circulation changed in the past, as well as how Earth's Milankovitch cycles have influenced the pacing of ice ages over the Pleistocene and Pliocene. [19] Raymo's Anti-phase Hypothesis [20] explains the 41,000 year pacing of Earth's climate cycles from 3 to 1 million years ago as due to the out-of-phase response of the northern and southern polar ice sheets to orbital precession at this time.
Raymo has also made contributions to the stratigraphy and dating of the past by means of oxygen isotope analysis of foraminifera from deep ocean sediments. This included publishing the first continuous oxygen isotope stratigraphy and time scale of the northern hemisphere Ice Ages from DSDP Site 607. [21] [22] In 2005, with her post-doc Lorraine Lisiecki who led the project, Raymo published the widely adopted 5-million-year LR04 benthic isotope stack which defines Marine isotope stages and continues to be the chronological benchmark against which most studies of the last 5.5 Ma are measured. [23]
In 1996, Raymo published the first paleo-CO2 estimate for the Middle Pliocene Warm Period using carbon isotopes of marine organic matter. [24] This was a time three million years ago when global temperatures were about 2-3 °C above preindustrial levels and their CO2 estimate, between 350 and 400 ppm, later became the inspiration for the name of the activist organization 350.org [25] which advocates for a return to 350 ppm as a safe level of carbon dioxide in the atmosphere.
In an analysis of collapsed polar ice sheets during the stage 11 Marine Isotope Interglacial (MIS), Raymo and Jerry X. Mitrovica computed global sea-level variations over the past 500 kyr. In their analysis, they assumed that the melting of the East Antarctic Ice Sheet (EAIS) and the Greenland Ice Sheet (GIS) happened towards the end of this interglacial period. [26] One of the methods they used in their examination involved using a “gravitationally self-consistent theory”. Additionally, the researchers performed a Monte Carlo parameter where they observed mantle viscosity, lithospheric thickness, and the duration of the break during MIS 11 (Raymo & Mitrovica, 2012). Raymo and Mitrovica have said that employing this method “yields a preferred bound on the peak eustatic sea level (ESL) during MIS 11”. Understanding the durability of existing ice sheets amidst climate change remains a significant concern for societal safety.
During the PLIOMAX project, Raymo formulated a method for correcting shorelines during the Pliocene period, for post-depositional isostatic changes (PLIOMAX, n.d.). [27] One of the main hurdles the PLIOMAX project faced was the ability to adjust and verify the model performance under CO2 and climate conditions (PLIOMAX, n.d.). [28] The accuracy of accessible paleoclimate data hindered these factors as mentioned earlier (PLIOMAX, n.d.). In another analysis, Raymo and her colleagues examined how polar ice sheets evolved during previous warm periods, specifically during the Pliocene period. For their research, the scientists examined existing evidence of previous sea levels and ice sheet constructions (Dutton et al., 2015). Despite many geological advances in the understanding of global mean sea level during previous warm periods, potential research hindrances still exist for future paleoclimate researchers. For instance, the peak heat temperatures during previous warm periods may have varied on the span of the respective interglacial period, which suggests that warm periods that lasted thousands of years may not represent “equilibrium conditions for the climate-cryosphere system” (Dutton et al., 2015). Additionally, it is currently not possible for researchers and scientists to make exact estimates of peak global mean sea level during the Pliocene period.
In a research paper by Raymo and her colleagues, they explained that the majority of existing sea level projections focus on shorter timelines of less than 2000 years, however, longer timeline projections are critical for predicting potential future sea-level heights to effectively develop long-term sea level defense infrastructure (Kemp et al., 2015). [29] The demand to present location-specific details regarding future sea level projections in the midst of climate change is a critical aspect of climatology research because of the growing concentration of socioeconomic and residential activity along global coastlines. [29]
In 2002, she was included by the illustrated magazine Discover in a list of the 50 most important women in science [30] [31] and in her nomination for the Wollaston Medal, Professor James Scourse described her as "one of the foremost and influential figures in the last 30 years...She's been an important role model to women scientists—you can get to the top. " [8] . Following this, in 2003 she became a fellow of John Simons. [32]
Raymo has won various prizes for her scientific work, including becoming in 2014 the first woman to be awarded the prestigious Wollaston Medal - the highest award of the Geological Society of London. [8] [33] In 2014, she received the Milutin Milankovic Medal [34] [31] at the European Geosciences Union’s annual meeting for her use of geochemistry, geology and geophysics to solve paleoclimatology’s big problems. [35] In 2016 she was elected a member of the National Academy of Sciences. [31] As well, in 2017 Raymo became a fellow of the Explores Club and became and received the Honoris Causa from the University of Lancaster, Great Britain. [31] In 2019 she was awarded the Maurice Ewing Medal by the American Geophysical Union. [36] Raymo is a fellow of the American Geophysical Union and the American Association for the Advancement of Science. In 2022 she was elected as a Member of the Royal Swedish Academy of Sciences, Class for Geosciences. [31]
There have been five or six major ice ages in the history of Earth over the past 3 billion years. The Late Cenozoic Ice Age began 34 million years ago, its latest phase being the Quaternary glaciation, in progress since 2.58 million years ago.
The Hoxnian Stage was a middle Pleistocene stage of the geological history of the British Isles. It was an interglacial which preceded the Wolstonian Stage and followed the Anglian Stage. It is equivalent to Marine Isotope Stage 11. Marine Isotope Stage 11 started 424,000 years ago and ended 374,000 years ago. The Hoxnian is divided into sub-stages Ho I to Ho IV. It is likely equivalent to the Holstein Interglacial in Central Europe.
The Wolstonian Stage is a middle Pleistocene stage of the geological history of Earth from approximately 374,000 until 130,000 years ago. It precedes the Last Interglacial and follows the Hoxnian Stage in the British Isles.
The geologic temperature record are changes in Earth's environment as determined from geologic evidence on multi-million to billion (109) year time scales. The study of past temperatures provides an important paleoenvironmental insight because it is a component of the climate and oceanography of the time.
The Illinoian Stage is the name used by Quaternary geologists in North America to designate the Penultimate Glacial Period c.191,000 to c.130,000 years ago, during the late Middle Pleistocene (Chibanian), when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes the Sangamonian Stage and follows the Pre-Illinoian Stage in North America. The Illinoian Stage is defined as the period of geologic time during which the glacial tills and outwash, which comprise the bulk of the Glasford Formation, accumulated to create the Illinoian Glacial Lobe.
The Elster glaciation or, less commonly, the Elsterian glaciation, in the older and popular scientific literature also called the Elster Ice Age (Elster-Eiszeit), is the oldest known ice age that resulted in the large-scale glaciation of North Germany and other parts of Europe. It took place approximately 500,000–400,000 years ago. It succeeded a long period of rather warmer average temperatures, the Cromerian Complex. The Elster was followed by the Holstein interglacial, which was followed Saale glaciation. The glacial period is named after the White Elster, a right tributary of the Saale.
The Mindel glaciation is the third youngest glacial stage in the Alps. Its name was coined by Albrecht Penck and Eduard Brückner, who named it after the Swabian river, the Mindel. The Mindel glacial occurred in the Middle Pleistocene; it was preceded by the Haslach-Mindel interglacial and succeeded by the Mindel-Riss interglacial.
The Beestonian Stage is an early Pleistocene stage in the geological history of the British Isles. It is named after Beeston Cliffs near West Runton in Norfolk where deposits from this stage are preserved.
The Pastonian interglacial, now called the Pastonian Stage, is the name for an early or middle Pleistocene stage of geological history in the British Isles. It precedes the Beestonian Stage and follows the Pre-Pastonian Stage. Unfortunately the precise age of this stage cannot yet be defined in terms of absolute dating or MIS stages. The Pre-Pastonian Stage is equivalent to the Tiglian C5-6 Stage of Europe and the Pre-Illinoian I glaciation of the early Pre-Illinoian Stage of North America.
The Bramertonian Stage is the name for an early Pleistocene biostratigraphic stage of geological history the British Isles. It precedes the Pre-Pastonian Stage. It derives its name from Bramerton Pits in Norfolk, where the deposits can be found on the surface. The exact timing of the beginning and end of the Bramertonian Stage is currently unknown. It is only known that it is equivalent to the Tiglian C1-4b Stage of Europe and early Pre-Illinoian Stage of North America. It lies somewhere in time between Marine Oxygen Isotope stages 65 to 95 and somewhere between 1.816 and 2.427 Ma. The Bramertonian is correlated with the Antian stage identified from pollen assemblages in the Ludham borehole.
Marine isotope stages (MIS), marine oxygen-isotope stages, or oxygen isotope stages (OIS), are alternating warm and cool periods in the Earth's paleoclimate, deduced from oxygen isotope data derived from deep sea core samples. Working backwards from the present, which is MIS 1 in the scale, stages with even numbers have high levels of oxygen-18 and represent cold glacial periods, while the odd-numbered stages are lows in the oxygen-18 figures, representing warm interglacial intervals. The data are derived from pollen and foraminifera (plankton) remains in drilled marine sediment cores, sapropels, and other data that reflect historic climate; these are called proxies.
The Plio-Pleistocene is an informally described geological pseudo-period, which begins about 5 million years ago (Mya) and, drawing forward, combines the time ranges of the formally defined Pliocene and Pleistocene epochs—marking from about 5 Mya to about 12 kya. Nominally, the Holocene epoch—the last 12 thousand years—would be excluded, but most Earth scientists would probably treat the current times as incorporated into the term "Plio-Pleistocene"; see below.
The Holstein or Holsteinian interglacial, also called the Mindel-Riss interglacial (Mindel-Riß-Interglazial) in the Alpine region, is the third to last major interglacial in Europe before the Holocene, the present warm period. It followed directly after the Elster glaciation and came before the Saale glaciation, during the Middle Pleistocene. The more precise timing was historically controversial since Holstein was commonly correlated to two different marine isotope stages, MIS 11 and MIS 9. Recent scholarship has supported a MIS 11 date, spanning approximately 421-395,000 years ago.
In geochemistry, paleoclimatology and paleoceanography δ18O or delta-O-18 is a measure of the deviation in ratio of stable isotopes oxygen-18 (18O) and oxygen-16 (16O). It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis. In paleosciences, 18O:16O data from corals, foraminifera and ice cores are used as a proxy for temperature.
The 100,000-year problem of the Milankovitch theory of orbital forcing refers to a discrepancy between the reconstructed geologic temperature record and the reconstructed amount of incoming solar radiation, or insolation over the past 800,000 years. Due to variations in the Earth's orbit, the amount of insolation varies with periods of around 21,000, 40,000, 100,000, and 400,000 years. Variations in the amount of incident solar energy drive changes in the climate of the Earth, and are recognised as a key factor in the timing of initiation and termination of glaciations.
Marine Isotope Stage 11 or MIS 11 is a Marine Isotope Stage in the geologic temperature record, covering the interglacial period between 424,000 and 374,000 years ago. It corresponds to the Hoxnian Stage in Britain.
Paleoceanography and Paleoclimatology is a peer-reviewed scientific journal published by the American Geophysical Union. It publishes original research articles dealing with all aspects of understanding and reconstructing Earth's past climate and environments from the Precambrian to modern analogs. Until the first of January 2018 the name of the journal was Paleoceanography.
Lorraine Lisiecki is an American paleoclimatologist. She is a professor in the Department of Earth Sciences at the University of California, Santa Barbara. She has proposed a new analysis of the 100,000-year problem in the Milankovitch theory of climate change. She also created the analytical software behind the LR04, a "standard representation of the climate history of the last five million years".
Marine Isotope Stage 9 was an interglacial period that consisted of two interstadial and one stadial period. It is the final period of the Lower Paleolithic and lasted from 337,000 to 300,000 years ago according to Lisiecki and Raymo's LR04 Benthic Stack. It corresponds to the Purfleet Interglacial in Britain, the Holstein Interglacial in continental Europe, and the Pre-Illinoian in North America.
The Don Glaciation, also known as the Donian Glaciation and the Donian Stage, was the major glaciation of the East European Plain, 0.8–0.5 million years ago, during the Cromerian Stage of the Middle Pleistocene. It is correlated to Marine Isotope Stage 16, approximately 650,000 years ago, which globally contained one of the largest glacial volumes of the Quaternary.