Since the negotiation of the United Nations Convention on the Law of the Sea, there have been many changes in our understanding of earth processes. One area of science that was not addressed in either the Convention or the Scientific and Technical Guidelines of the Commission on the Limits of the Continental Shelf is climate change and its potential impact on sea level. Recent studies have provided overwhelming and irrefutable scientific evidence that, despite a decrease in solar insolation, the average global temperature of the Earth has risen approximately 0.9° C over the last 136 years, with most of this increase occurring over the past 35 years. This increase in temperature is the result of an increase in atmospheric CO2 that can be demonstrated (chemically) to be associated, for the most part, with the burning of fossil fuels. The increase in temperature has resulted in the thermal expansion of sea water and the melting of temperate glaciers and the Greenland and Antarctic ice sheets, driving a rise of sea level of more than 30 cm over the past 100 years. Predictions of future rise in sea level range from another 30 cm to almost a metre over the next 80 years, depending on the levels of CO2 in the atmosphere and the uncertainty of the modeling. Beyond 2100, sea level can rise even more, with predictions as much as 3 m by 2300 if there is no reduction in the rate of input of anthropogenic CO2 into the atmosphere. Along with the direct impact that sea level rise would have on residents of coastal regions, such dramatic changes in sea level will also have an impact on the area of maritime zones, boundaries with neighboring States, and, in the most dramatic cases, the inundation of islands that may lead to the partial or total disappearance of a coastal State. Changes in sea level will likely invoke the concurrent movement of the outer limits of the territorial sea, contiguous zone, and the exclusive economic zone, all of whose limits are measured from the coastal State’s baselines. Even more intriguing is the impact of such changes in baselines on the limits of the continental shelf which are also defined relative to the baselines, but, as stated in article 76(8) of the Convention, if the limits of the continental shelf are established based on the recommendations of the Commission on the Limits of the Continental Shelf, they shall be “final and binding.” These and many other intriguing questions about the impact of rising sea level on maritime zones will present challenges to legal scholars in the years to come.