Past Climate Science Speakers

04/22/2014 - 4:00pm | A Changing Biosphere and the Future of Planet Earth
G. Warfield "Skip" Hobbs

Since its creation 4.5 billion years ago, Earth has experienced constant change. Whereas geologic change usually requires tens of thousands—if not hundreds of thousands or millions—of years, human civilization has made and continues to make profound changes to the planet in a much shorter time. These changes have altered the chemistry and physical state of the atmosphere and oceans at rates that have not previously occurred in geologic history, except possibly during a few cataclysmic events. This talk will discuss the human factor in geologic change, its effect on the biosphere, and the importance of sustainability in all future natural resource extraction.

G. Warfield “Skip” Hobbs is Managing Partner of Ammonite Resources Company, an international petroleum geotechnical and business consulting firm located in New Canaan, Connecticut. Hobbs was 2011 President of the American Geological Institute, a nonprofit federation of 47 geoscientific and professional associations that was founded in 1948 and represents more than 120,000 geologists, geophysicists and other earth scientists. He has also served as President of the American Association of Petroleum Geologists (AAPG) Division of Professional Affairs, President of the Eastern Section of AAPG, and is a trustee of the New Canaan Nature Center. Hobbs is a graduate of Yale University Department of Geology & Geophysics.

Kline Geology Laboratory Auditorium (KGL 123) See map
210 Whitney Avenue
New Haven, CT 06511
04/14/2014 - 2:00pm | Impacts of Aerosols on Arctic Mixed-Phase Boundary Clouds During M-PACE and ISDAC Field Campaigns: Implications for Modelling Studies
Greg McFarquhar, University of Illinois, Department of Atmospheric Sciences

Comprehensive data on arctic boundary layer aerosol and cloud microphysical and radiative properties were collected during the 2004 Mixed-Phase Arctic Cloud Experiment (M-PACE) and the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC). During M-PACE, the University of North Dakota Citation executed spiral ascents and descents through 27 mixed-phase clouds on 7 separate days over ground-based remote sensing sites at Barrow and Oliktok Point, Alaska. Data from in-situ microphysical sensors have been used to characterize how cloud particle shape, size, phase and bulk properties vary with height. These data have been used extensively to evaluate models that have contributed to our fundamental understanding of microphysical processes in mixed-phase clouds and produced potential explanations about the role of aerosols on observed ice nuclei concentrations.

However, M-PACE data were insufficient to evaluate all model hypotheses on causes of mixed-phase cloud persistence due to uncertainties in the microphysical data, the lack of information on aerosol composition and radiative properties, and the limited range of aerosol, surface and meteorological conditions over which data were obtained. ISDAC overcame these limitations and allows for an examination of the influence of aerosols on clouds influenced by ice. During ISDAC, the National Research Council of Canada Convair-580 flew 27 sorties, collecting data with an unprecedented 42 cloud and aerosol instruments for more than 100 hours on 12 different days. Data obtained above, below and within single-layer stratus during three separate days are allowing for a process-oriented understanding of how aerosols affect the microphysical and radiative properties of arctic clouds. Ultimately these data will be used to improve the representation of cloud and aerosol process in models covering a variety of spatial and temporal scales, and to determine the extent to which long-term surface-based measurements at a ground site at the North Slope of Alaska can provide retrievals of aerosols, clouds, precipitation and radiative heating in the Arctic. The need for future measurement campaigns in the Arctic to enhance the range of conditions sampled will also be discussed.

03/03/2014 - 2:00pm | South Pacific Convergence Zone (SPCZ) Variability and Biases in Models. Ben Lintner, Rutgers Climate Institute POSTPONED


The South Pacific Convergence Zone (SPCZ) is a key deep convective feature of Pacific basin climate, especially in austral summer when it extends from the tropical western Pacific warm pool to Southern Hemisphere (SH) midlatitudes halfway across the Pacific basin. In the context of climate simulation, a wide range of simulated SPCZ behaviors is evident in current generation models, e.g., coupled general circulation models often produce an excessively zonal climatological SPCZ. In this talk, the variability and biases in the SPCZ as simulated in the suite of Coupled Model Intercomparison Project Phase 5 (CMIP5) models are described. In particular, diagnostics developed from empirical orthogonal function and composite analyses are used to evaluate CMIP5-simulated SPCZ-region relationships among large-scale circulation, moisture vertical structure, and precipitation across multiple timescales and to compare to available observations.  Results of ongoing research involving simulations with an intermediate level complexity model, the two-level Quasi-equilibrium Tropical Circulation Model (QTCM2), are also presented.  These simulations serve to highlight some of the key processes impacting the SPCZ.


[1] Lintner, B.R., and J.D. Neelin, 2008: Eastern margin variability of the South Pacific Convergence Zone. Geophys. Res. Lett., 35, L16701, doi:10.1029/2008GL034298.

[2] Niznik, M.J., and B.R. Lintner, 2013:  Circulation, moisture, and precipitation relationships along the South Pacific Convergence Zone in reanalyses and CMIP5 models.  J. Clim., 26, 10174—10192, doi:10.1175/JCLI-D-13-00263.1.

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Kline Geology Laboratory Auditorium, (Rm 123) See map
210 Whitney Ave
New Haven, CT 06511
02/07/2014 - 2:00pm | Grand Challenges of Clouds: From Ice Crystal Formation to the Influence of Aerosols and Clouds on Climate. Ulrike Lohmann, IAC-ETH
Prof. Ulrike Lohmann

Ulrike Lohmann is Full Professor for Experimental Atmospheric Physics in the Institute for Atmospheric and Climate Science since October 2004.

She was born in 1966 in Berlin (Germany) and studied from 1988 to 1993 Meteorology at the Universities of Mainz and Hamburg. In 1996, she obtained her PhD in climate modelling from the Max Planck Institute for Meteorology. Prior to her current appointment, she was a post-doctoral fellow at the Canadian Centre for Climate Modelling and Analysis in Victoria and an Assistant and Associate Professor at Dalhousie University in Halifax (Canada). She was awarded a Canada Research Chair in 2002 and was elected as a fellow of the American Geophysical Union in 2008.

Her research focuses on the role of aerosol particles and clouds in the climate system. Of specific interest are the formation of cloud droplets and ice crystals and the influence of aerosol particles on the radiation balance and on the hydrological cycle in the present, past and future climate. She combines laboratory work, field measurements, satellite data and different numerical models.

Ulrike Lohmann has published more than 180 peer-reviewed articles. She was a lead author for the Fourth and Fifth Assessment Reports of the Intergovernmental Panel for Climate Change (IPCC). She is the coordinator of the EU FP7 project BACCHUS. At ETH, she is the head of the Institute for Atmospheric and Climate Science since 2006.

Kroon Hall See map
195 Prospect Street
New Haven, CT 06511
11/18/2013 - 2:00pm | Going Local: Making Climate Assessments More Relevant for Decision Makers In New England
Cameron Wake, Research Associate Professor, Earth Systems Research Center Institute for the Study of Earth, Oceans, and Space, University of New Hampshire

Cameron Wake is a research associate professor in climatology at the Institute for the Study of Earth, Oceans and Space at the University of New Hampshire.  He also has a joint appointment in the UNH Department of Earth Sciences and is the Josephine A. Lamprey Fellow in Climate and Sustainability at the UNH Sustainability Institute. Cameron leads a research program investigating regional climate and environmental change through the analysis of ice cores, instrumental data, and phenological records, with a focus on the northeast United States, the Arctic, and central Asia.  His collaborative research on several regional climate assessments in the northeast United States has been shared with state and federal agencies and representatives, has been covered widely in the media, and has been cited by several as motivation for policy action. He is an author on over 70 papers published in the peer-reviewed scientific literature and dozens of reports, and has provided hundreds of interviews for state, regional and national media.

Cameron also directs Climate Solutions New England, a regional network promoting energy self-reliance and weather resilient communities so that secure renewable energy is the common condition and vulnerability to our changing climate reduced.

Dr. Wake received a B.Sc. in Geology (1984) from the University of Ottawa, an M.A. in Geography (1987) from Wilfrid Laurier University, and a Ph.D. in Earth Sciences (1993) from the University of New Hampshire.

10/28/2013 - 2:00pm | New York City's Special Initiative for Rebuilding and Resilience: Strengths and Limitations of Climate Model-Based Approaches
05/02/2013 - 4:00pm | Ice Cloud Seeding: A Viable Geoengineering Mechanism?
Professor Trude Storelvmo — Yale University
Kline Geology Laboratory (KGL) See map
210 Whitney Ave
New Haven, CT
04/10/2013 - 10:00am | The Risks and Efficacy of Solar Geoengineering
David Keith — Harvard University

David Keith appointments are at Harvard where he serves as the Gordon McKay Professor of Applied Physics in the School of Engineering and Applied Sciences (SEAS) and Professor of Public Policy at the Harvard Kennedy School.  Professor Keith has worked near the interface between climate science, energy technology and public policy for twenty years. He took first prize in Canada’s national physics prize exam, won MIT’s prize for excellence in experimental physics, and was listed as one of TIME magazine’s Heroes of the Environment 2009. David divides his time between Boston and Calgary where he serves as President of Carbon Engineering a start-up company developing industrial scale technologies for capture of CO2 from ambient air.


Solar geoengineering may enable a significant reduction in climate risks by partially offsetting climate change due to increasing greenhouse gases, however this emerging technology entails novel risks and uncertainties along with serious challenges to global governance. I will attempt a rough summary of the physics of solar geoengineering and present recent findings regarding (a) the climate’s response to radiative forcing by stratospheric aerosols, (b) methods of producing appropriate aerosol distributions, and (c) risks. In closing I will discuss the trade-off between solar geoengineering, emissions reductions and adaptation in climate policy.

Kline Geology Laboratory (KGL) See map
210 Whitney Ave
New Haven, CT