Bette L. Otto-Bliesner | |
---|---|
Born | Bette Lou Otto 1950 |
Alma mater | University of Wisconsin-Madison |
Scientific career | |
Institutions | National Center for Atmospheric Research |
Thesis | The dynamics of seasonal change of the long waves as deduced from a low-order general cirulation model (1980) |
Bette Otto-Bliesner is an earth scientist known for her modeling of Earth's past climate and its changes over different geological eras.
Otto-Bliesner graduated from William Fremd High School in Palatine, Illinois in 1968. [2] She has a B.S. in meteorology from the University of Madison-Wisconsin (1972). [1] In 1974, she earned her M.S. from University of Wisconsin - Madison with a thesis titled "Isentropically time-averaged mass circulations in the Northern Hemisphere". [3] She earned her Ph.D. from the University of Wisconsin-Madison in 1980, [4] and was an associate scientist there from 1980 to 1986. [5] After two years as a contract scientist at ARC Technologies, Otto-Bliesner joined the Department of Geology at the University of Texas at Arlington where she worked from 1990 to 1996. She joined the National Center for Atmospheric Research (NCAR) in 1997 where she was promoted to senior scientist in 2007. [5]
Otto-Bliesner has worked on multiple chapters in the Assessment Review reports from the Intergovernmental Panel on Climate Change, an organization which was awarded the 2007 Nobel Peace Prize for its long series of such reports. [6] [7] She was one of the 16 lead authors on the 2007 chapter on "Paleoclimate". [8] She was one of the 17 lead authors on the 2013 chapter on "Information from the Paleoclimate Archives". [9]
Otto-Bliesner's research connects paleogeographic information with global climate models. Through this approach, she has examined interactions between continental weathering and atmospheric carbon dioxide levels in the period from 570 to 425 million years ago, [10] revealed that deciduous forests help regulate temperatures in the Cretaceous period, [11] and identified factors leading to the persistence of snow on continental ice sheets. [12] Her modeling work has also assessed temporal variability in El Niño/La Niña cycles [13] [14] and regional summer monsoons. [15] Through models jointly considering atmospheric conditions and the ocean, Otto-Bliesner's research has linked deep ocean circulation and global climate in the late Cretaceous (80 million years ago) [16] and the Last Glacial Maximum. [17] [18] [19] [20] This research focus has revealed that changes in the Atlantic Meridional Overturning Circulation are linked freshwater input into the ocean [21] [22] and the Bølling-Allerød warming at the end of the last glacial period. [23] Through a combination of direct sampling and modeling, her research has detailed the forcing that led to the Little Ice Age. [24] [25] In polar regions, Otto-Bliesner has modeled variability in Arctic temperatures [26] which result in the retreat [27] or collapse [28] of polar ice sheets followed by increases in sea level. [29] [30]
Otto-Bliesner also works on developing the methods used to establish climate models and through this has enabled low-resolution depictions of atmospheric conditions that can be coupled with high-resolution circulation models. [31] [32] Through collaborative analysis of the effectiveness of climate models, Otto-Bliesner has examined the connections between greenhouse gasses and global warming, [33] [34] she has weighed the impact of the sun, volcanic ash, and greenhouse gasses on temperatures on Earth [35] and she participated in projects that evaluate climate models through comparisons with paleoclimate data. [36] [37] [38] Most recently, she helped establish the framework of the Community Earth System Model that links model forcing parameters with data from the last thousand years. [39]
In 2020, Jiang Zhu, Christopher Poulsen, and Otto-Bliesner published an analysis of the Coupled Model Intercomparison Project phase 6 (CMIP6) which revealed that the model is overly sensitive to atmospheric carbon dioxide levels and produces higher surface temperatures than would be predicted when the model is validated using historical data. [40] [41] The next IPCC assessment report will use CMIP6 in its predictions of future climate change, Otto-Bliesner noted "Figuring out whether the high climate sensitivity in CMIP6 models is realistic is of tremendous importance for us to anticipate future warming and to make adaptation plans”. [42]
Cloud feedback is a type of climate change feedback, where the overall cloud frequency, height, and the relative fraction of the different types of clouds are altered due to climate change, and these changes then affect the Earth's energy balance. On their own, clouds are already an important part of the climate system, as they consist of water vapor, which acts as a greenhouse gas and so contributes to warming; at the same time, they are bright and reflective of the Sun, which causes cooling. Clouds at low altitudes have a stronger cooling effect, and those at high altitudes have a stronger warming effect. Altogether, clouds make the Earth cooler than it would have been without them.
A sudden stratospheric warming (SSW) is an event in which polar stratospheric temperatures rise by several tens of kelvins over the course of a few days. The warming is preceded by a slowing then reversal of the westerly winds in the stratospheric polar vortex, commonly measured at 60 ° latitude at the 10 hPa level. SSWs occur about six times per decade in the northern hemisphere (NH), and about once every 20-30 years in the southern hemisphere (SH). In the SH, SSW accompanied by a reversal of the vortex westerly was observed once during the period 1979–2024; this was in September 2002. Stratospheric warming in September 2019 was comparable to or even greater than that of 2002, but the wind reversal did not occur.
The Last Interglacial, also known as the Eemian, was the interglacial period which began about 130,000 years ago at the end of the Penultimate Glacial Period and ended about 115,000 years ago at the beginning of the Last Glacial Period. It corresponds to Marine Isotope Stage 5e. It was the second-to-latest interglacial period of the current Ice Age, the most recent being the Holocene which extends to the present day. During the Last Interglacial, the proportion of CO2 in the atmosphere was about 280 parts per million. The Last Interglacial was one of the warmest periods of the last 800,000 years, with temperatures comparable to and at times warmer than the contemporary Holocene interglacial, with the maximum sea level being up to 6 to 9 metres higher than at present, with global ice volume likely also being smaller than the Holocene interglacial.
A circumpolar vortex, or simply polar vortex, is a large region of cold, rotating air; polar vortices encircle both of Earth's polar regions. Polar vortices also exist on other rotating, low-obliquity planetary bodies. The term polar vortex can be used to describe two distinct phenomena; the stratospheric polar vortex, and the tropospheric polar vortex. The stratospheric and tropospheric polar vortices both rotate in the direction of the Earth's spin, but they are distinct phenomena that have different sizes, structures, seasonal cycles, and impacts on weather.
Climate sensitivity is a key measure in climate science and describes how much Earth's surface will warm for a doubling in the atmospheric carbon dioxide (CO2) concentration. Its formal definition is: "The change in the surface temperature in response to a change in the atmospheric carbon dioxide (CO2) concentration or other radiative forcing." This concept helps scientists understand the extent and magnitude of the effects of climate change.
The Atlantic meridional overturning circulation (AMOC) is the main ocean current system in the Atlantic Ocean. It is a component of Earth's ocean circulation system and plays an important role in the climate system. The AMOC includes Atlantic currents at the surface and at great depths that are driven by changes in weather, temperature and salinity. Those currents comprise half of the global thermohaline circulation that includes the flow of major ocean currents, the other half being the Southern Ocean overturning circulation.
The Mars general circulation model is the result of a research project by NASA to understand the nature of the general circulation of the atmosphere of Mars, how that circulation is driven and how it affects the climate of Mars in the long term.
Polar amplification is the phenomenon that any change in the net radiation balance tends to produce a larger change in temperature near the poles than in the planetary average. This is commonly referred to as the ratio of polar warming to tropical warming. On a planet with an atmosphere that can restrict emission of longwave radiation to space, surface temperatures will be warmer than a simple planetary equilibrium temperature calculation would predict. Where the atmosphere or an extensive ocean is able to transport heat polewards, the poles will be warmer and equatorial regions cooler than their local net radiation balances would predict. The poles will experience the most cooling when the global-mean temperature is lower relative to a reference climate; alternatively, the poles will experience the greatest warming when the global-mean temperature is higher.
The Mid-Piacenzian Warm Period (mPWP), or the Pliocene Thermal Maximum, was an interval of warm climate during the Pliocene epoch that lasted from 3.3 to 3.0 million years ago (Ma).
John E. Kutzbach was an American climate scientist who pioneered the use of climate models to investigate the causes and effects of large changes of climate of the past.
Axel Timmermann is a German climate physicist and oceanographer with an interest in climate dynamics, human migration, dynamical systems' analysis, ice-sheet modeling and sea level. He served a co-author of the IPCC Third Assessment Report and a lead author of IPCC Fifth Assessment Report. His research has been cited over 18,000 times and has an h-index of 70 and i10-index of 161. In 2017, he became a Distinguished Professor at Pusan National University and the founding Director of the Institute for Basic Science Center for Climate Physics. In December 2018, the Center began to utilize a 1.43-petaflop Cray XC50 supercomputer, named Aleph, for climate physics research.
Amy C. Clement is an atmospheric and marine scientist studying and modeling global climate change at the University of Miami's Rosenstiel School of Marine, Atmospheric, and Earth Science.
Cyclonic Niño is a climatological phenomenon that has been observed in climate models where tropical cyclone activity is increased. Increased tropical cyclone activity mixes ocean waters, introducing cooling in the upper layer of the ocean that quickly dissipates and warming in deeper layers that lasts considerably more, resulting in a net warming of the ocean.
M. Joan Alexander is an atmospheric scientist known for her research on gravity waves and their role in atmospheric circulation.
Fixed anvil temperature hypothesis is a physical hypothesis that describes the response of cloud radiative properties to rising surface temperatures. It presumes that the temperature at which radiation is emitted by anvil clouds is constrained by radiative processes and thus does not change in response to surface warming. Since the amount of radiation emitted by clouds is a function of their temperature, it implies that it does not increase with surface warming and thus a warmer surface does not increase radiation emissions by cloud tops. The mechanism has been identified both in climate models and observations of cloud behaviour, it affects how much the world heats up for each extra tonne of greenhouse gas in the atmosphere. However, some evidence suggests that it may be more correctly formulated as decreased anvil warming rather than no anvil warming.
Jean Lynch-Stieglitz is a paleoceanographer known for her research on reconstructing changes in ocean circulation over the last 100,000 years.
The Rodwell–Hoskins mechanism is a hypothesis describing a climatic teleconnection between the Indian/Asian summer monsoon and the climate of the Mediterranean. It was formulated in 1996 by Brian Hoskins and Mark J. Rodwell [d]. The hypothesis stipulates that ascending air in the monsoon region induces atmospheric circulation features named Rossby waves that expand westward and interact with the mean westerly winds of the midlatitudes, eventually inducing descent of the air. Descending air warms and its humidity decreases, thus resulting in a drier climate during the summer months. The interaction of this atmospheric flow with topography further modifies the effect.
The Agulhas Leakage is an inflow of anomalously warm and saline water from the Indian Ocean into the South Atlantic due to the limited latitudinal extent of the African continent compared to the southern extension of the subtropical super gyre in the Indian Ocean. The process occurs during the retroflection of the Agulhas Current via shedding of anticyclonic Agulhas Rings, cyclonic eddies and direct inflow. The leakage contributes to the Atlantic Meridional Overturning Circulation (AMOC) by supplying its upper limb, which has direct climate implications.
Thomas L. Delworth is an atmospheric and oceanic climate scientist and Senior Scientist at the Geophysical Fluid Dynamics Laboratory (GFDL), part of NOAA. He also serves on the faculty of Oceanic Science at Princeton University.
Ronald J. Stouffer is a meteorologist and adjunct professor at the University of Arizona, formerly Senior Research Climatologist and head of the Climate and Ecosystems Group at the Geophysical Fluid Dynamics Laboratory (GFDL), part of NOAA. He has also served on the faculty of Princeton University.
the scientific reports it has issued over the past two decades
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