Understanding and addressing climate change requires the collection of a significant amount of environmental data. Although satellites can best collect much of this data, it is not possible for one nation to collect all relevant climate data on its own, and there are currently gaps in relevant satellite data collection. Further, much of the data that is collected is not shared freely, but instead has barriers to access that limit its use for both scientific research and operational purposes. This research examined the development of data sharing policies to identify the barriers and incentives to international sharing of climate data collected by satellites. Quantitative analysis of satellite data-sharing policies for Earth observation data as well as case studies of domestic agencies in the U.S., Europe, and Japan, showed that limitations in data sharing are due to 1) a belief that data can efficiently be treated as a commodity, a viewpoint which conflicts with experience for nearly all climate data; 2) the lack of recognition of the normative justification for sharing climate data, though this norm exists for weather data; and 3) insufficient agreement that international cooperation and data sharing are required to adequately monitor climate change. These limitations exist due to uncertainties about the nature of the market for climate data, the inadequate understanding of climate impacts and the ability to mitigate them, and an inadequate understanding of the requirements of climate science and operational activities. To address this situation, countries should adopt free and open policies, recognizing that social benefit is maximized when data is treated as a public good and freely shared, and that cost recovery and commercialization of scientific satellite data are not viable. Countries should also share climate data internationally because it has the potential to save lives and property, creating a moral requirement for sharing. Finally, countries should agree on a minimal set of climate data that must be shared to adequately monitor climate. This agreement should be institutionalized by World Meteorological Organization (WMO) resolution framework, similar to WMO Resolution 40, which addressed weather data sharing.