The Bridge Collaborative operates under the direction of our four founding Secretariat members who guide decision-making and the implementation of our work.

KATHARINE KREIS, Secretariat Member

Katharine Kreis is the Director of Strategic Initiatives and Lead for Nutrition Innovation at PATH. Her work is predominantly focused on identifying new tools, technologies and methodologies to help better track, predict, target and address malnutrition. Prior to joining PATH, Katharine held senior positions at the Global Alliance For Improved Nutrition and the Bill & Melinda Gates Foundation. She also served as a US Foreign Service officer with the US Agency for International Development, where she managed a development portfolio aimed at improving health outcomes. Katharine has served on a number of advisory councils, including the Micronutrient Forum and the World Economic Forum’s Global Agenda Council on Nutrition.

LYDIA OLANDER, Ph.D., Secretariat Member

Lydia Olander directs the Ecosystem Services Program and is an adjunct associate professor at the Nicholas Institute for Environmental Policy Solutions at Duke University. She leads the National Ecosystem Services Partnership which has worked with the US government to incorporate ecosystem services into federal decision making. She also works on environmental markets and mitigation, including forestry and agricultural-based climate mitigation; wetland, stream and endangered species mitigation; and water quality trading.
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CLAUDIA RINGLER, Ph.D., Secretariat Member

Claudia Ringler is the Deputy Division Director of the Environment and Production Technology Division at the International Food Policy Research Institute (IFPRI), a member of CGIAR, a global research partnership for a food-secure future. She currently leads IFPRI’s Natural Resource Management group, co-leads the Institute’s water research program and is also a flagship co-lead for the CGIAR Research Program on Water, Land and Ecosystems. She chairs the Food, Energy, Environment and Water Nexus network, and is or has been a member at various international assessments as well as policy panels. Claudia is a recognized thought leader on water for food and natural resource management with a focus on the Global South.

HEATHER TALLIS, Ph.D., Secretariat Chair

Heather Tallis is Global Managing Director and Lead Scientist for Strategy Innovation at The Nature Conservancy, the world’s largest environmental organization. She is a recognized scientific leader in bringing human well-being considerations into conservation, making connections to education, health, poverty alleviation, water management, agriculture, security, infrastructure development and national accounts. Heather directs the iTeam, an effort to bring innovation and integration to conservation. Previously, Heather served the Conservancy as Chief Scientist and was Senior Research Scientist at Stanford University for the Natural Capital Project.


Together with the Secretariat and our network of members, our program staff make the Bridge Collaborative possible.

JOSH GOLDSTEIN, Ph.D., Bridge Collaborative Director, The Nature Conservancy

As the Director of the Bridge Collaborative, Josh works with the Secretariat and staff to engage leaders, practitioners and researchers across the health, development and environment communities to create shared evidence and drive toward lasting outcomes for people and the world we share. Based at The Nature Conservancy, Josh has worked for over 15 years on projects around the world to mainstream incorporation of nature’s benefits to people in policy, planning and business contexts. Prior to joining the Conservancy, Josh was an assistant professor at Colorado State University. He received his Ph.D. in Environment and Resources from Stanford University in 2007.

RYAN CALDER, Ph.D., Postdoctoral Fellow, Duke University

Ryan’s research quantifies environmental and human health impacts of civil infrastructure and policy interventions. He holds a doctorate in environmental health from the Harvard T.H. Chan School of Public Health, as well as master and bachelor degrees in civil engineering from Concordia University, Canada. He has worked as an analyst for Quebec’s environment ministry, as an engineer in environmental consulting and as a research fellow at the Harvard John A. Paulson School of Engineering and Applied Sciences. His expertise centers on integrated modeling of fate and transport of waterborne contaminants, and the resulting human exposures and health outcomes. Ryan is more broadly interested in environmental policy and management of emerging risks.

SARA MASON, Policy Associate, Duke University

Sara Mason works as a policy associate at the Nicholas Institute for Environmental Policy Solutions at Duke University. She received her Master of Environmental Management degree from Duke, focusing in ecosystem science and conservation. Sara is part of the Ecosystem Services Program at the Nicholas Institute, and she works as one of the coordinators for the National Ecosystem Services Partnership. Her work currently focuses on ways to integrate ecosystem services into decision-making and on the interdisciplinary nature of biodiversity conservation. Prior to joining the Nicholas Institute, Sara worked in ecological field research and endangered animal rehabilitation.


Elizabeth Bryan is a Senior Scientist at IFPRI where she conducts policy-relevant research on sustainable agricultural production, natural resource management, small-scale irrigation, climate change and gender. Her current work focuses on trade-offs and synergies across the intersection of climate-smart agriculture, nutrition, gender and the environment, and she has published widely on these topics. Prior to joining IFPRI, Elizabeth worked at the World Bank’s Poverty Reduction Group and the Latin American Program of the Woodrow Wilson International Center for Scholars. Elizabeth holds an M.A. in International Development from American University.