The threats posed by climate change to the global environment have fostered heightened scientific interest in marine geo-engineering schemes designed to boost the capacity of the oceans to absorb atmospheric carbon dioxide. This is the primary goal of a process known as ocean fertilization which seeks to increase the production of organic material in the surface ocean in order to promote further draw down of photosynthesized carbon to the deep ocean. This article describes the process of ocean fertilization, its objectives and potential impacts on the marine environment and some examples of ocean fertilization experiments. It analyses the applicability of international law principles on marine environmental protection to this process and the regulatory gaps and ambiguities in the existing international law framework for such activities. Finally it examines the emerging regulatory for legitimate scientific experiments involving ocean fertilization being developed by the London Convention and London Protocol Scientific Groups and its potential implications for the proponents of ocean fertilization trials.