Reuben is an economist and climate finance expert specializing in international economics, climate risk, and sustainable finance. He is the founder of the Kenya Climate and Nature Directory and the Director of Climate Shapers Africa Limited. He sits on the Steering Committee of the United Nations Environment Programme (UNEP) AgriFood Project in Kenya.

Reuben has consulted for various institutions including the World Bank, Rockefeller Philanthropy Advisors, Central Bank of Kenya, multiple UN agencies, among others. He has been a speaker at high-level forums by the International Energy Agency, International Emissions Trading Association (IETA), Glasgow Financial Alliance for Net Zero (GFANZ), Alliance for Financial Inclusion (AFI), among others.

His work has been featured in leading platforms such as the Centre for Economic Policy Research (CEPR), Green Central Banking, World Economic Forum, and Project Syndicate. He has won several awards, including the St. Gallen Wings of Excellence Award and the Rudi Dornbusch Prize in International Economics. He has authored over a dozen articles, commissioned reports, and two book chapters.

As an industry expert, he has facilitated in-country workshops in Côte d'Ivoire, Cameroon, Eswatini, Kenya, Senegal, South Africa, and Tanzania, training over 1,500 senior executives. As a subject expert on greening financial systems, he has trained central bankers from over 20 countries. He served as a Senior Climate Risk Expert on the Central Bank of Kenya (CBK) technical assistance programme that developed the Kenya Green Finance Taxonomy. 

Reuben holds a Master in International Economics from the Geneva Graduate Institute (Switzerland) and a Bachelor in Financial Economics from Strathmore University (Kenya). He is currently a PhD candidate in International Economics at the Geneva Graduate Institute. As adjunct faculty, he has taught at the University of Cape Town (South Africa) and Strathmore Business School (Kenya).

An avid traveler, he has visited 23 countries.