"This postdoc program was one of the most important steps in building my career, providing exactly the foundation I needed for future success. I had incredible opportunities to pursue research grants for climate-related studies and collaborate with world-class scientists in hydrology, geochemistry, social science, and law from inside Columbia and beyond. The program gave me flexibility to conduct independent and collaborative research and publish with exceptional co-authors."
Program and Application Details
Overview
Through the Climate School Postdoctoral Research program, Columbia University’s Climate School supports the scholarship needed to tackle climate change and its related global challenges. The Climate School works to offer solutions through transdisciplinary research, partnerships, education, innovative technology, building knowledge, and the sharing of ideas.
The Climate School Postdoctoral Research program is the premier program in the world for those dedicated to a better understanding of critical scientific and social issues in Climate as well as in global sustainable development. Climate School Postdoctoral Researchers will join multidisciplinary teams of outstanding, committed scientists to advance our scientific understanding of these challenges and develop practical responses to address them.
Successful postdoctoral candidates are matched with Principal Investigators and mentors from across the Climate School, including the Climate School’s research centers and programs, the Lamont-Doherty’s Earth Observatory, Columbia University Medical Center, and other affiliated schools and departments.
The program provides innovative postdoctoral scholars with the opportunity to build a foundation in one of the core disciplines represented within the Climate School (sustainability, the environment, social justice, and the geosciences), while at the same time acquiring the breadth of cross-disciplinary expertise needed to address critical issues related to sustainable development. Specific areas of research include carbon neutral economy, adapting to future climate, earth fundamentals, resilient ecosystems, climate, and social systems, and climate justice and equity. The program offers a unique intellectual surrounding that fosters cross-disciplinary interaction, research, and education.
To apply, candidates must complete the online application and submit a proposal for research that would contribute to the goal of global sustainable development. Proposals may suggest participating in, contributing to, or extending existing multidisciplinary Climate School projects. Candidates are also encouraged to develop new, innovative projects that connect Climate School expertise. In addition to submitting the application and proposal, candidates are encouraged to identify and contact their desired multidisciplinary mentoring team, i.e., two or more senior faculty members or research scientists/scholars at Columbia University with whom they would like to work during their appointment.
We encourage research proposals for topics from all areas of climate and sustainable development, with a particular interest in the following Climate School’s foundational knowledge areas:
Earth Systems and Sustainability
Scientific understanding underpins evidence-based solutions to climate variability and change, and other related sustainability challenges such as biodiversity loss and environmental contamination. This pillar includes the foundational understanding of past, current, and future climate, along with connected systems including the oceans, biosphere, atmosphere and lithosphere, and anthroposphere. This pillar captures, for example, discoveries and advances in our understanding of feedbacks, tipping points, and extreme events within and across systems. It also provides a basis for the development, provision, and co-production of climate and other environmental information (including predictions and projections) that is reliable, actionable, usable, understandable, and equitably accessible to all. This pillar also includes foundational knowledge that underpins solutions for the energy transition, carbon removal from the atmosphere, and nature-based solutions.
Social Systems and Justice
This pillar is a home for understanding how social systems operate, including the role of historical legacies in shaping injustice and the climate/environmental crisis, as well as how societies have transformed in the past and could transform in the future. Focus areas include enhancing well-being and livelihood, climate finance, reducing poverty and promoting peace and inclusive participation in governance, and international development. Research and education in this pillar focus on context- and scale-appropriate, equitable responses to climate change, the adoption of new technologies, and the transformation of societies toward just and sustainable futures.
Analytics for Action
This pillar describes approaches, methods, and tools for 1) enhancing understanding within and across the other two pillars, and 2) building to large-scale action and impact. This pillar includes development of the core data sets and models used to understand and predict climate variability and change, as well as climate impacts and solutions. Innovative techniques include Data Sciences and Artificial Intelligence. Methods that enhance co-production of knowledge with diverse communities outside the university build fundamental knowledge while bridging towards action and impact based on local contexts and on broad collaborations. Monitoring and evaluation of the impact of climate actions are also essential to the iterative learning and implementation processes that can lead to transformation.
Questions? Email [email protected].
The Lamont-Doherty Earth Observatory (LDEO) also awards postdoctoral fellowships in the earth, environmental, and ocean sciences. Please visit the LDEO Postdoctoral Fellowship page for more information.
Program Details
Start Date and Duration: Climate School Postdocs are appointed for twelve months with a possible extension of twelve more months, contingent on funding. Appointments typically begin on September 1; however, depending on individual circumstances, as well as the needs of a postdoc’s host research unit, appointments may begin as early as July 1.
Application Opens: Wednesday, September 3, 2025
Application Deadline: Friday, October 31, 2025, by 11:59 pm Eastern Time
Funding: Climate School Postdocs will receive an annual salary of $72,116. They are also awarded a research stipend of $7,000 for reimbursable expenses related to the appointment. These funds can be used for relocation and moving expenses, as well as for computers, travel, conference, journal, book, software, equipment, and other research costs.
External Funding: CCS Postdocs are encouraged to participate in the development and submission of research proposals in cooperation with their mentors, host research units, or other researchers. When doing so, they must follow all Columbia University rules applicable to postdoctoral scholars.
Visas: Columbia University only grants limited-term J1 visas for non-US citizens. Read more information on Columbia’s visa eligibility policies online.
Benefits: CCS Postdocs are considered Officers of Research and are eligible for benefits provided by Columbia University for full-time employees. For more information, please visit Columbia's Office of Human Resources online. The rules, regulations, and policies that govern employment at Columbia are also listed on the website.
Orientation: A series of information sessions and visits to Climate School research units.
Spring and Fall Symposia: Two public symposia per year in which both first-year and second-year postdocs present their research and participate in discussions with the audience. The symposia provided a great opportunity for postdocs to engage the Columbia research community as well as the larger public in innovative research in sustainable development.
Postdoctoral Seminars: A seminar series in which each postdoc presents her or his ongoing research. Visiting speakers also participate in the seminars. Postdocs may also coordinate group projects that are designed, discussed, and implemented during these times. The meetings are informal and designed to foster interdisciplinary and problem-solving discussions among CCS Postdocs, faculty, and researchers. Lunch is provided.
Other Climate School Seminar Series: Climate School Postdocs receive invitations to other events and speaker series at Columbia, including those sponsored by the Climate School's Lamont-Doherty Earth Observatory (LDEO), Goddard Institute for Space Studies (GISS), Center for Environmental Research and Conservation (CERC), Earth Engineering Center (EEC), and the Center for International Earth Science Information Network (CIESIN).
Questions? Email [email protected]
Application Guidelines
Eligibility
To be eligible for the program, candidates must have received their doctoral degrees (Ph.D., M.D. or J.D.) within three years prior to the start of the appointment. All doctoral requirements must be fulfilled and the degree awarded before the start of the appointment. People holding current positions with rank above post-doctoral scientist are not eligible for appointment under university rules. Those holding current post-doc positions should contact our office to determine eligibility. The program is open to U.S. and non-U.S. citizens. Columbia University is an affirmative action/equal opportunity employer. Minorities and women are encouraged to apply.
Application
Deadline: Friday, October 31, 2025 by 11:59 pm Eastern Time
To apply to the program candidates must submit the following documents:
- Online Application
- Curriculum Vitae
- Brief Personal History
- Research Proposal
- 3 Recommendation Letters
In addition to submitting the application and proposal, applicants are encouraged to contact their desired multidisciplinary mentoring team, i.e. two or more senior faculty members or research scientists/scholars at Columbia University with whom they would like to work during their appointment. Please note that an endorsement from a faculty member or researcher does not guarantee acceptance into the program.
Brief Personal History Format
Two (2) page maximum, double-spaced; one-inch margins, minimum 11 point standard font. The personal statement should include the following elements based on their relevance to your situation
- Brief personal introduction and research statement.
- Paragraph in your personal statement that addresses the Climate School’s mission.
- Summary of any discussions you have had with potential mentors. Note: endorsement from a faculty member or researcher does not guarantee acceptance into the program.
- Explanation of gaps in employment or studies (these will be considered on a case-by-case basis).
- Prior postdoctoral positions - Columbia University policy only allows a cumulative maximum of 5 years in a postdoctoral position, whether held at or outside of the university. If you have prior postdoc experience, please contact Esteban Andrade to discuss your application.
Recommendation Letters
Three (3) recommendation letters are required by Friday, October 31, 2025, 5pm Eastern Time. Once an application is successfully submitted, the references listed will receive an email with the Applicant ID and the link to upload their letter. Applicants are strongly encouraged to apply early and to request that their referees send in letters in a timely manner.
Note: We strongly recommend informing your references of the request for a letter in advance of submitting your application. We also recommend following up with your references after you have applied to ensure that they have received the information to upload their letter.
Research Proposal Format
Five (5) page maximum; double-spaced; one-inch margins; minimum 11 point standard font.
Bibliographic references are required but not counted toward the 5-page maximum. They should be included in the same document.
The research proposal should address how the proposed work will contribute to the goal of global sustainable development. Proposals may suggest participating in, contributing to, or extending existing multidisciplinary Climate School projects. Candidates are also encouraged to develop new, innovative projects that connect Climate School expertise. You must include a title for your research proposal.
Research Foci and Mentors
Research foci are determined by the postdocs themselves. Thus, Climate School Postdocs play an active, independent role in developing their own areas of expertise and research agendas. Candidates are encouraged to review the list of the Climate School's research units and relevant Columbia University departments to see the breadth of potential mentors and collaborators actively engaged in research at the university.
Candidates are strongly encouraged to identify and contact a mentor prior to applying. Candidates are also encouraged to scope additional members of the Columbia Climate School who hold the rank of Assistant Professor / Research Scientist or higher.
Selection Procedure
Applications are reviewed by the Climate School Postdoctoral Selection Committee, which is composed of senior Climate School faculty from across the School. Care is taken to ensure that all of the Climate School's core disciplines are represented in the Committee.
An initial, rigorous review of the applications examines several factors, including the following:
- Strength of the research proposal
- Relevance to the Climate School's mission and research themes
- Interdisciplinary and collaborative potential
- Practice/policy/community engagement relevance
- Previous academic experience
- Strength of academic/professional references
Applications that merit further consideration are moved forward to the directors of one or more relevant Climate School research units. Based on feedback received from the research units, the Selection Committee reevaluates the applications in great detail before reaching a final decision.
Decisions
Appointments will be announced in April 2026.
Climate School’s mission
The mission of the Columbia Climate School is “to further knowledge and educate leaders to achieve equitable and just solutions to the changing climate and related sustainability challenges.”
Please include a paragraph in your personal statement that addresses the Climate School’s mission. Applicants should explain how their research and experience exemplify or advance this mission and include specific examples from their academic pursuits and accomplishments. We particularly value work that is attentive to the distinct needs within and among communities and contributes meaningfully to the public good.
News
What I’ve Learned From ‘The End of Poverty,’ 20 Years Later
The author reflects on Jeffrey Sachs, the U.N., and the need to redesign global institutions for a world shaped by climate change, poverty and geopolitical strain.
How Do Glacial Ecosystems Respond to Climate Change?
Microbiologist Arwyn Edwards discusses the complex role of microbial life in glacial ecosystems and the impact of climate change on his field.
You Asked: What Exactly Is a ‘Super’ El Niño?
Columbia Climate School experts explain what a strong El Niño could mean for the planet this year.
Events
OCP Seminar: Ashwin Seshadri, IISc Bangalore
Columbia Climate School Research Seminar Series - Rebecca Dell
Climate LIVE K12: Youth-focused Climate Solutions
Our Postdocs
2025-2027 Cohort
Lovees Lueong
Lovees Lueong is an environmental geographer and climate justice scholar whose work advances inclusive climate finance for vulnerable communities in Central Africa. His research explores how participatory, gamified digital platforms can democratize access to climate funding and amplify the voices of women, smallholder farmers, and forest-dependent groups typically excluded from adaptation planning. At Columbia’s Climate School, Lovees is investigating the Inclusive Design of Gamified Climate Finance Platforms under the mentorship of Professor Daniel Osgood. This work bridges climate science, governance, and equity by developing accessible, culturally sensitive tools that promote transparency, local governance, and community-led adaptation. He holds a Ph.D. in Geography and Planning from the University of Bamenda, where he also served as a graduate teaching assistant. Lovees is a member of the Cameroon Academy of Young Scientists (CAYS). His academic work spans environmental justice, deforestation dynamics, climate governance, and gendered vulnerability. He is a recipient of the Conservation Action Research (CARN) Grant. Lovees is passionate about decolonizing climate knowledge and embedding equity into the architecture of global climate finance.
Pavi Selvakumar
Pavi Selvakumar is an environmental social scientist interested in how communities navigate sustainability, environmental justice, and resilience in the face of today’s climate challenges. She earned her Ph.D. in Environmental Science from Oklahoma State University. Her dissertation investigated how institutional structures, campus culture, state politics, and leadership priorities influence the development of sustainability initiatives at U.S. land-grant universities. She holds a bachelor’s degree in Information Technology from India and a master’s degree in Environmental Assessment and Management from the United Kingdom. Her interdisciplinary background drives a research approach that combines technical fluency with a strong foundation in environmental policy and social inquiry. As a postdoctoral researcher at the Columbia Climate School, she contributes to the Resilient Coastal Communities Project (RCCP), exploring how artificial intelligence and community-based modeling can be integrated to support equitable climate adaptation and resilience planning in frontline communities.
2024-2026 Cohort
Clara Chang
Clara Chang received her PhD from Columbia University in 2024 in Earth and Environmental Science. She is a geologist broadly interested in the intersections between environmental science and public health. In her role as a postdoctoral scholar at the Columbia Climate School, she will work with the CU Superfund Northern Plains Research Program on systems research on water quality and environmental justice concerns on tribal lands.
Amel Derras-Chouk
Amel is a physicist who uses satellite data to quantify uncertain cloud properties and develops analytical models to explain them. Although clouds’ importance in, for example, transporting moisture globally or reflecting solar radiation is well understood, clouds make up the largest uncertainties in climate feedback projections. Amel works with Dr. Greg Elsaesser to improve physical models of deep convective anvil clouds, explaining ordered properties that emerge from their complex behavior to reduce feedback uncertainties. With a Ph.D. in condensed matter physics from CUNY Graduate Center, Amel brings an interdisciplinary background to her research, which she has applied to quantifying vertical velocity in deep convective clouds.
Rebecca Gustine
Becca recently completed her PhD at Washington State University in Water Resources Engineering. Her research focuses on the connections between climate change, snow, and food and water security. She uses physically based models and remote sensing. Becca frequently works with water and natural resources managers to improve climate adaptation of watersheds and food and water systems. As a postdoctoral fellow at The Climate School and Lamont Doherty Earth Observatory, Becca is working with Dr. Alex de Sherbinin and Dr. Joerg Schaefer on the connections between changes in the cryosphere, water resources, food and water security, and human migration.
Sheehan Moore
Sheehan Moore is an environmental anthropologist studying the ways coastal communities adapt to climate change and land loss. His research traces responses to subsidence and erosion on the Gulf coast of Louisiana, with attention to resource extraction, new forms of land restoration planning, and shifting technologies of spatial governance. By centering struggles over environmental racism and land defense, he studies how efforts to manage climate threats can shape the geography of crisis and possibilities for action. At the Columbia Climate School, Sheehan works as a postdoctoral fellow with Dr. Paige West and Dr. Alexander de Sherbinin on issues including climate migration and managed retreat. His fieldwork with Louisiana residents and environmental scientists was supported in part by a research grant from the Fonds de recherche du Québec – Société et culture. Sheehan received his PhD in anthropology from the City University of New York (CUNY) Graduate Center and has a BA in anthropology from McGill University. Website: sheehanmoore.com
Ariana Salas Castillo
Ariana Salas Castillo is a political scientist interested in the role played by interest groups and institutions in shaping social and climate policies in the global South. In her doctoral dissertation, she studied the political economy of bus public transportation reforms in urban Costa Rica and Chile. While carrying out this work, Ariana realized the immense social justice, environmental, climate and public health power embedded in public transportation.
As a postdoctoral research scientist at the Columbia Climate School, Ariana will join the Global Research Consortium An Equity, Ecosystems and Engaged Approach to Informal Transport and Shared Mobility, where she will focus on the study of popular transportation in the global South.
Ariana earned her Ph.D. in Political Science from the University of California, Santa Barbara. She also holds an M.A. on Sustainable Territorial Development from a joint program between the University of Padova, KU Leuven, and Paris-Sorbonne 1, as well as a B.Sc. in Economics from the University of Costa Rica. Prior to her Ph.D., Ariana held a research position at the Tropical Agricultural Research and Higher Education Center (CATIE) in her native Costa Rica.
Kevin Schwarzwald
Kevin Schwarzwald is an interdisciplinary climate scientist, helping inform climate impacts projections and decision-making under uncertainty. His postdoc research focuses on understanding the sensitivity of estimates of future climate impacts to climate uncertainty; in short, determining when decision-makers need to consider which sources of climate uncertainty to ensure they are prepared for the true range of possible future outcomes. Kevin earned his PhD in Earth and Environmental Sciences from Columbia University, working at the International Research Institute for Climate and Society (IRI) and Lamont-Doherty Earth Observatory on understanding the drivers of the East African long and short rains and why climate models struggle to simulate them. He also holds a BA in physics and public policy from the University of Chicago and a Master of Law in China Studies from Peking University's Yenching Academy (how promotion pressures on local officials encourage inefficient urban expansion in smaller cities in China). Kevin is the co-founder of NENSIC (nensic.org), an interdisciplinary network for young researchers working in climate and environmental issues from any angle. Prior to his graduate studies, Kevin focused on climate projections for economic and policy uses and has been involved with climate and policy work in Europe, America, and Africa. Website: kevinschwarzwald.com
2023-2025 Cohort
Shams Azad
Dr. Shams Azad earned his doctoral degree from New York University, where his research is dedicated to the comprehensive exploration of hazardous pollutant exposure and the discernment of direct and indirect effects of extreme events and conditions with advanced sensing techniques and data-driven methodologies. As a postdoctoral research scientist at the Columbia Climate School, he collaborates closely with Dr. Steven Chillrud on developing high-resolution models pertaining to groundwater metal exposure within the U.S. Northern Plains region. He earned B.S. from the Bangladesh University of Engineering and Technology and M.S. from Stuttgart University of Applied Sciences.
Peterson Faina
Peterson Faina is a Postdoctoral Research Scientist in the Postdoctoral Research Program of Columbia University’s Climate School. He received his Ph.D. in June 2023 at the University of Antananarivo Madagascar in collaboration with Geosciences and Anthropology departments at the University of Massachusetts (UMASS) Amherst. From 2014 until he obtained his PhD, he worked with a team of paleoclimatologists, paleontologists, and biogeochemists from UMASS Amherst and the Massachusetts Institute of Technology (MIT) to understand the mechanisms that cause climate change and to reconstruct Madagascar’s recent climate history and its effects on environments, large endemic vertebrates, and people. For his Postdoc appointment, Peterson is studying how climate change impacts habitat, resource utilization and food security in Madagascar. He hopes to disentangle the impacts of human activity and climate, and to reveal the impacts on humans of changes in resource availability (food resources) in southwest and central Madagascar.
Nicolas Lippolis
Nicolas Lippolis is a political economist interested in how economic ideas, political institutions, and changes to the global economy shape the development strategies of countries in the Global South. His doctoral research at the University of Oxford examined the drivers of industrial policy in Angola and Ethiopia at a time of high commodity prices and China’s global rise. As a postdoctoral researcher at Columbia Climate School, Nicolas is conducting research on how states in Africa and Latin America navigate financial constraints, a decarbonizing world economy, and China’s global presence to chart strategies for energy transitions and green industrialization.
Prior to the doctorate, Nicolas earned an MSc in Economics for Development and a BA in Philosophy, Politics and Economics, both from Oxford University. He has taught at Oxford, Sciences Po Paris, and the University of Paris 1 Panthéon-Sorbonne. He has also consulted with the World Bank, and previously worked in emerging markets macroeconomic research at Goldman Sachs in London. Nicolas is a native of Rio de Janeiro, Brazil.
The Columbia Climate School Postdoctoral Research program has provided postdoctoral scholars with the opportunity to engage in cross-disciplinary sustainable development research. Over 120 alumni have completed the postdoctoral program, coming from diverse backgrounds that include law, theology, medicine, science, economics, engineering, ethnomusicology, and anthropology.
Most alumni go on to pursue careers in higher education and have accepted academic positions at universities such as Columbia University, Indiana University, Oberlin College, and University College London. Others have joined NGOs, government, and the private sector, or started their own companies.
2023-2025 Cohort
Bianca Carducci
Ian Gray
Maya Moore
Asya Svirinovsky-Arbeli
Anna-Katharina von Krauland
Andrew Wang
2022-2024 Cohort
Isatis M. Cintron-Rodriguez
Dylan S. Davis
Manuel P. Linsenmeier
Enquye Negash
Kathelyn Paredes Villanueva
Nadia Seeteram
2021-2023 Cohort
Thalia Balkaran
Farideh Hosseini Narouei
Yue Huang
Daniel Green
Leah Jones-Crank
2020-2022 Cohort
Amanda Baxter
Sarah Garland
Festival Godwin Boateng
Arturo Pacheco-Solana
Muye Ru
Cascade Tuholske
2019-2021 Cohort
Ben Bales
Spencer Hill
Robbie Parks
Beth Tellman
Liv Yoon
2018-2020 Cohort
J. Nicolas Hernandez-Aguilera
Weston Anderson
James Jones
Winslow Hansen
Megan Maurer
Elisabeth Nebie
Sha Zhou
2017-2019 Cohort
Allison Bridges
Pilar Fernández
Maron Greenleaf
Anand Osuri
Andy Stock
2016-2018 Cohort
Ruthie Birger
Kyle Davis
Alexandra Karambelas
Milad Kharratzadeh
Ding Ma
Nandini Velho
2015-2017 Cohort
Madison Condon
Robert Elliott
Xiaohui Feng
Justin Mankin
Hannah Nissan
Jeffrey Paller
2014-2016 Cohort
Graeme Blair
Booyuel Kim
Shauna Downs
Martina Kirchberger
W. Victoria Lee
Shira Mitchell
2013-2015 Cohort
Katherine Alfredo
Elliot Cohen
Tanya O’Garra
Aurelie Harou
David Kanter
Ezra Markowitz
Jilian A Sacks
Katya Vasilaky
2012-2014 Cohort
Astrid Dannenberg
Joshua Fisher
Jesse Lasky
Emilie Perge
Tess Russo
Gary Watmough
Leigh Whittinghill
2011-2013 Cohort
Tien Ming Lee
Ying Li
Jaime Madrigano
Nada Petrovic
James Tamerius
Katherine Tully
Shelley Welton
Meng Xu
2010-2012 Cohort
Ana Arjona
Andrew Bell
Sarah Kaschula
Hope Michelson
Alexandra Morel
Daniel Soto
Annika Sweetland
Tara Troy
Derek Willis
2009-2011 Cohort
Shahzeen Attari
Ilana Brito
Chao Chen
Gillian Galford
Jonathan Hickman
Carlos Pérez
2008-2010 Cohort
Stergios Athanassoglou
Sandra Baptista
Liza Comita
Elisabeth King
Chie Sakakibara
Sean Smukler
Leigh Winowiecki
2007-2009 Cohort
Haimanti Bhattacharya
Daven Henze
Cassidy Johnson
Melissa Keeley
Erin Lothes Biviano
Mary Nyasimi
Gretchen Peltier
Kenneth Shirley
2006-2008 Cohort
Alex Awiti
Matthew Bonds
Darby Jack
Florence Kondylis
Brenda Lin
Valerie Mueller
Deborah Salon
Tobias Siegfried
Ulrich Wagner
2005-2007 Cohort
Susan Doll
Vladimir Gil
Rebekah Green
Franco Montalto
Murugi Ndirangu
Michael Reilly
Roland Russell
Christian Webersik
2004-2006 Cohort
Lee Addams
Yanis Ben Amor
Kristina Czuchlewski
Fabrice De Clerck
Christopher Doll
Jane Carter Ingram
Harounan Kazianga
Bijan Khazai
Caroline Korves
Nikhil Krishnan
Cristina Maria Rumbaitis-del Rio
Nori Tarui
2003-2005 Cohort
Susanne Bauer
Mary Booth
Jennifer Cole
Jonathan Donner
Ben Evans
Guillermo Franco
Nobuyuki Hanaki
Kate Jones
Martin Sandbu
Anton Seimon
Yesim Tozan
Jessika Trancik
2002-2004 Cohort
Angela Bednarek
Brian Mailloux
Nicky Sheates
2001-2003 Cohort
Liliana Botcheva-Andonova
Saugata Datta
Tracy Holloway
Lensyl Urbano
2000-2002 Cohort
Peter Dodds
Joe Thornton
1999-2001 Cohort
Zoltan Takacs
Xianzhong Wang