Our Team

Our Team

Annelise Gill-Wiehl

Annelise GIll-Wiehl

Annelise Gill-Wiehl is a NSF Graduate Student Researcher and a Ph.D. Candidate in the Energy & Resources Group at the University of California, Berkeley (UCB). At UCB, she is a research fellow at the Berkeley Carbon Trading Project, where she is working on a comprehensive over- and under-crediting analysis of cookstove projects on the voluntary carbon market. She has six years of cookstove fieldwork experience in Tanzania, where she currently lives. Prior to entering the workforce, Gill-Wiehl studied both Environmental Engineering and International Development Studies at Notre Dame. Outside of work, Annelise enjoys long distance running, listening to political comedy, and facetiming her Yorkshire terrier who didn’t move with her to Tanzania.


Arif Cemil Ozcanlar

Offering an experience of over 25 years in the Creative and Technology segments backed with extensive international experience of over 15 years across Europe, America, West Africa, South Africa, Australia, and South East Asia. Cemil is a dynamic team leader with exceptional collaborative and interpersonal abilities.You will normally find him partnering closely with client teams, conducting ideation and progress sessions, mentoring teams, building road maps and pipelines, researching, prototyping and observing users. He has helped to build world-class mobile apps and websites for banks, insurance companies, telcos and hospitals and many more.

Carlos Velazquez

Carlos Velazquez

Carlos graduated from the Georgia Institute of Technology with a bachelor’s degree in Environmental Engineering. He recently completed agroecology and forest restoration projects for both the Urban Resource Initiative and Environmental Leadership Training Initiative, as well as water resource infrastructure plans and technical proposals at CSA Group. He is originally from Puerto Rico and is currently completing a dual master’s degree in environmental management and engineering from Yale and Tsinghua Universities. In his free time, Carlos enjoys hiking through the forests of Puerto Rico, playing guitar, and learning new languages.

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Carrie Wentzel

Carrie holds a bachelor’s degree in Environmental Science with a minor in Foreign Affairs from the University of Virginia. Prior to joining Calyx, she consulted for the Environmental Defense Fund. This past year, she lived in Fiji completing a Fulbright Research Grant in collaboration with Conservation International on blue carbon in seagrass meadows across the Lau provence. In her free time, Carrie enjoys scuba diving, reading, and long hikes.

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Chiara Canetti

Chiara graduated from Utrecht University with a bachelor’s degree in Global Sustainability Science. She is originally from Italy but has lived in Berlin, Germany, for the past 3 years. Currently, she is pursuing  her master in Integrated Natural Resource Management at Humboldt University of Berlin. For the past 3 years, she has been working as a volunteer at Grounded, a Dutch sustainable events organization. In her free time, Chiara enjoys cycling, photographing, learning about agroecology and medicinal herbs. 

Dave Bren round photo

Dave Bren

Dave is a seasoned fintech leader with deep experience in investment analytics, ratings and in scaling SaaS businesses. His roles include leading product management/strategy and go-to-market for the original Moody’s Analytics subsidiary, product and global R&D for Fitch Solutions, and sales and product management for CreditSights’ risk business. More recently, Dave has worked on building the partnerships, sales, and marketing functions as chief revenue officer for fast-growing SaaS cybersecurity startup Kriptos; and was go-to-market and partnerships leader for new productivity applications at Amazon Web Services. Dave has degrees in International Relations from Pomona College and UCSD’s graduate school of Global Policy & Strategy. In his free time you’ll find Dave hiking the open space preserves of the San Francisco peninsula and watching lots of soccer.


Deborah Lawrence

Deborah Lawrence is an environmental sciences professor at the University of Virginia, where she conducts global forest and climate research. Previously, she was a science advisor to the US Department of State, Office of Global Change (the international climate change policy and negotiations unit). She later helped establish SilvaCarbon, a US federal interagency program for forest carbon measurement and monitoring. Deborah has also served on the Technical Committee on Agriculture, Forestry and Other Land Use at the American Carbon Registry. She received a BA in Anthropology from Harvard University, and a PhD in Botany from Duke University. Deborah’s favorite activities include tending to her climate-forward backyard, where she must constantly defend her beloved chickens from foxes.


Donna Lee

Donna has worked on climate change for nearly two decades. She was formerly at the State Department where, among other duties, she served as a climate change negotiator for the United States; thereafter, she served as an advisor to governments, philanthropies, and companies seeking to take climate action. Her goals in life align with Calyx’s mission: to contribute to the well-being of people and to protect the planet. Donna has a B.S. in Electrical Engineering and a Masters in Education from UCLA, and a Masters in International Policy from Stanford University. In her free time, you can find Donna wandering the Colorado Rockies by foot or on nordic skis.


Duncan van Bergen

Duncan set up and led a global nature-based carbon project investment and development business and worked for two decades in the energy business before that. He cares deeply about ecosystem preservation and aligning this with societal and economic development. Duncan has degrees in economics and management from the University of Louvain and the Solvay Business School and an MBA from the Harvard Business School. He is a passionate runner and an avid reader.

Floor Oosterlee

Floor Oosterlee

Floor holds a bachelor’s degree from University of Amsterdam, and master’s degree from University of Bath, both in European Studies, a master’s degree in International Relations from Utrecht University. In 2022, she completed an Executive MBA from Maastricht University. Prior to joining Calyx, she worked at Shell for five years on the energy transition and the nature-based solutions team. Floor also worked in corporate social responsibility for the Dutch NGO NL Cares. In her free time, Floor enjoys going on long treks on her road bike and walking with her new dog. Originally from the Netherlands, she works remotely, traveling from beautiful locale to beautiful locale across Europe.


Gustavo Andrade Reginato

Gustavo holds a BA in Forest Engineering and an MBA in Environmental Management and Technologies from Universidade de Sao Paulo. For more than 10 years his work has been related to climate change and sustainable development for non-governmental organizations and the private sector in Brazil, Colombia and abroad. In his free time, Gustavo enjoys petting his adopted dog Lupita, learning more about Colombia, or checking out the latest in the cinema.

Ivy Aygeiwaa Amponsah

Ivy Aygeiwaa Amponsah

Ivy holds a BA in Political Science and Sociology from the University of Ghana and an MA in International Studies and Diplomacy from SOAS University of London. Prior to joining Calyx, she worked with a Ghanaian-based think tank as a research consultant, including studying the revenue management and producer pricing mechanisms within Ghana’s cocoa sector. Ivy is currently pursuing a second master’s degree in International Administration and Policy from the University of Potsdam. In her spare time, Ivy enjoys spending quality time with her family and friends.

UPDATED Linda Revera Macedo

Linda Rivera Macedo

Linda is a political and legal advisor specialized in international law, environmental policy and human rights. She has more than 16 years of experience in different sectors ranging from government, law firms, ngos and consulting firms. Before joining calyx, Linda worked for the permanent mission of Mexico to the United Nations in Geneva. Linda holds a law degree from the National Autonomous University of Mexico, a Master degree in Public International law from The University of Nottingham, UK and a Master in Environmental Science from the University of Geneva in Switzerland. Linda lives in Spain and loves to practice yoga and get away with her family to spend time in nature.

Matteo Lattanzi

Matteo Lattanzi

Matteo holds a bachelor’s degree in Political Science and a master’s degree in Sustainable Development from Utrecht University. Prior to joining Calyx, he covered various research roles at Climate Focus and at TMG, a sustainability think tank. While there, he became familiar with voluntary carbon markets and nature based solutions. In his free time, Matteo often heads out to climb with his friends, or enjoys learning about gardening and permaculture. Born in Rome, Italy, he has lived in Berlin, Germany, for the past 3 years.


Rahmi Ariani

Rahmi holds degrees in Applied Meteorology (B.Sc.) and Applied Climatology (M.Sc.) from Bogor Agricultural University in Indonesia. Currently, she is pursuing her PhD at the University of Goettingen, Germany. Her PhD focuses on evaluating and improving the performance of land surface models to estimate carbon stock and carbon fluxes in forest ecosystems. She loves living in a diverse society as it teaches her to be open-minded and broadens her perspective. In her free time, she likes being active by playing sports, dancing and teaching herself to play piano.

Ryan Carrol (UPDATED)

Ryan Carroll

Ryan is a Geographic Information Systems (GIS) and remote sensing specialist with 10+ years experience providing geospatial solutions for environmental and natural resource applications. He recently finished a Master’s thesis in land cover mapping at Georg-August University in Germany. Originally from Pittsburgh, Pennsylvania in the United States, he now splits his time between the US and Spain. Ryan holds a Bachelor of Arts in Geography (Natural Resources Management) from San Diego State University, and a Master of Science in Forest and Ecosystem Sciences (Tropical and International Forestry) from Georg-August University. When he’s not staring at his computer monitor, you can find Ryan surfing along the coast or hiking in the mountains.

Steve Barker

Steve Barker

Steve Barker graduated from the University of Virginia with a bachelor’s degree in Environmental Science after completing an Associate of Science degree at Piedmont Virginia Community College. Before joining Calyx Global, he worked for two years as an environmental analyst at Daybreak, collecting data on environmental hazard sites. Steve spends most of his spare time at the gym with friends or playing high level competitive Esports.

Ryan Cooper

Ryan Cooper

Ryan holds a Bachelor’s degree in Psychology from SUNY Binghamton and is currently pursuing his Master of International Business at Tufts University. He has experience assessing climate change impacts at Gap, Inc. and has worked as a Land Analyst for Novis Renewables in New York. Ryan spent two years working on food security in rural Nepal with the Peace Corps and learned about local food production on farms in Maine and New York, USA. In his spare time, Ryan enjoys cooking, playing guitar, and growing food.


Tao Jiang

Tao holds a master degree on Forestry management from Beijing Forestry University (China) and now is doing his PhD in Forestry at University of Göttingen (Germany). His research interests focus on applying deep learning on forest monitoring. He is also interested in research on deforestation monitoring and predicting deforestation drivers. In his free time, he likes traveling and hiking with his small drone.

Wesley Roberts

Wesley Roberts

Wesley has over ten years experience working on REDD+ at both the project and national scale. He began his career in geographic information systems research and quickly moved to the private sector where he led the geo-spatial components of voluntary carbon market projects. After 3 years, he began supporting national scale forest inventory projects and REDD+ readiness activities focused on Forest Reference Emission Levels and National Forest Monitoring systems. Wesley has a PhD in Environmental Science from University of KwaZulu-Natal and is a South African. When not facilitating carbon project ratings or supporting forest inventory work, he can be found cycling one of  the numerous mountain bike routes in the Western Cape. He also enjoys reading science fiction and walking on the beach with his wife.

Zihui Zhu

Zihui Zhu

Zihui has extensive forestry experience and expertise in geographic information systems and national and international forest policy. Her previous positions include 4 years as a project assistant at the National Forestry and Grassland Administration of China. She holds a master’s degree in forestry from Beijing Forestry University. She grew up in the very south of China and studied in Nanning, Beijing and Malmö. In addition to her work at Calyx Global, she is currently pursuing a Ph.D. at the University of Göttingen in Germany, while spending every free minute pursuing her enthusiasm for J-pop and ukulele.