The World Ocean plays a critical role in maintaining the planet's ecosystems and is essential to human health and well-being. Oceans help supply essential moisture to provide precipitation for freshwater supplies and support plant and animal populations. They also provide high-protein food resources and additional agricultural benefits, from animal feed to fertilizers. Yet an increasingly populated world and more than a century worth of human impacts - overfishing, oil extraction and spills, pollution from land sources, coastal development, and humankind's lack of understanding of the complexity of the ocean ecosystem - have led to an ecologically challenged ocean environment. Up until the twentieth century, the human population had only minor impacts on the ocean environment. Multiple government space agencies have used satellite instruments to study the oceans from space and to establish baseline environmental data, against which scientists can compare future observations and monitor the health of this globally vital resource.