There is no reason that I should prepare an introduction to the Ocean Health Index when Harrison Ford is perfectly capable of doing so. Watching this video will make you feel like you’re a sixth-grader on a field trip to an aquarium.
The Ocean Health Index is an endeavor by Conservation International, the New England Aquarium, and the National Geographic Society to establish a measurement system for the health of the world's oceans, a baseline index against which future changes can be measured. The project's (absolutely gorgeous) website explains up-front how we're doing. On a scale of 0 to 100, our oceans are at 60.
So what does that mean? The OHI assesses how the ocean areas off countries' coastlines are faring according to 10 goals: water cleanliness, biodiversity, food provision, artisanal fishing opportunities, natural products, carbon storage, coastal protection, coastal livelihoods, tourism, and sense of place. To compute the scores for each goal, several dozen components -- things like coral reef health, fisheries management, marine jobs, acidification -- were evaluated by researchers from the University of Santa Barbara and the University of British Columbia. Each country is scored on each goal on a 0-to-100 scale.