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WHAT IS THE OCEAN HEALTH INDEX?

This Index is the first comprehensive global measurement of ocean health that includes people as part of the ocean ecosystem.

Recognizing that people are now part of the ocean ecosystem, this Index evaluates how well the ocean provides 10 key benefits to people and how well we protect its ability to do so in the future.  It scores how well coastal countries and their marine territories optimize their potential ocean benefits. 

It is the first ocean assessment tool that scientifically compares and combines key elements from all dimensions of the ocean’s health – biological, physical, economic and social--- so that leaders, managers and the public can promote an increasingly beneficial future for all ocean life, including us.

By integrating information from many different disciplines and sectors the Index represents a significant advance over conventional single-sector approaches to assessing ocean condition.

Learn about the Ocean Health Index

More information about scores

More Information

How is the global score calculated?

The calculation of the Ocean Health Index for 2014 represents the first year that the Ocean Health Index has calculated a score for the entire global ocean. In past years, scores were only produced for the coastal ocean, i.e. from the coastline out to the boundaries of the Exclusive Economic Zones (EEZs) of coastal countries and territories, defined as 200 nm offshore. In 2014, Antarctica and the Southern Ocean along with the High Seas or Areas Beyond National Jurisdiction (ABNJ) (15 regions as defined by the Food and Agriculture Organization) were also assessed. 

The global Ocean Health Index score is the area-weighted average of scores for all 220 EEZs, Antarctica and the Southern Ocean along with the High Seas or Areas Beyond National Jurisdiction (ABNJ) 
Each reporting area is evaluated for 10 goals.  Each goal scores from 0 to 100, where a score of 100 means that optimal benefits are being fully realized for that goal.

The Method used by the Index to calculate the global score is as follows:

Scores for all ten goals are averaged within each region to give the region’s overall score. Then all regions’ overall scores are averaged, weighted by the respective areas of their regions, so that larger regions play a more important role in determining the global score because they represent a larger portion of the world’s oceans. 

The method used by the Index best captures the core principle that ocean health is the result of interactions among the ten goals in a particular location. For example, low scores in Biodiversity might be associated often with high scores in Natural Products, due to a tradeoff between the two goals. If the goal scores are averaged within each country, the score will reflect this interaction by assigning similar scores to places that do well in one or the other goal (all else being equal). 

Does the Ocean Health Index explain why a score is high or low?

Index scores are derived from approximately one hundred databases. Each database measures one or more specific factors, for example sea level rise, marine and terrestrial protected areas, coastal human population, the risk of extinction for marine species or iconic species, or the annual amount of revenue provided by industries in the marine sector.  

Sometimes the database contains information that explains a score.  For example, we can see that a large increase in protected areas caused South Georgia and the South Sandwich Islands’ score for the Lasting Special Places sub-goal to increase 95 points from 2012 to 2013. The database does not specify which areas were added, but exploration elsewhere reveals that a new 1 million square kilometer marine protected area was designated in 2012.  

On the other hand, some data layers do not contain information that explains their values or variation and those seeking such explanations must consult other sources. For example, to understand the underlying reasons why species were assigned the particular categorical extinction risks shown in the database, a reader would need to consult the narrative species accounts that form the basis of the International Union for Conservation of Nature “Red List.”  Similarly, to explain underlying causes of a nation’s variations in the amount of marine sector revenue, one would need to explore other sources of information about that country as well as the global economic background. Was there a global economic slowdown? Did environmental conditions affect the mariculture or tourism industries?  Was there political unrest or other disturbance?  Such information is beyond the scope of the Index.  

Though it may seem unsatisfying that the Index cannot provide all the answers we want, seeking them by digging deeper into its underlying databases (available online) and beyond will enrich anyone’s knowledge about the ocean and the world.

Why does the Biodiversity goal score so high when we know that species and habitats are declining?

The Ocean Health Index evaluates of species based on the categories for species extinction risk shown in the IUCN (International Union for the Conservation of Nature) Red List, the authoritative assessment of global extinction risks. Because IUCN assessments have been performed on relatively few species, data on some species that are threatened may not be available. In addition, it can take time before declines in species can be detected and reported by scientists. Although the current state of species looks relatively optimistic, nearly every country in the world has negative trends, so the likely future state of species looks much more pessimistic. 

The Index evaluates the extent of habitats based on their extent in about 1980. One reason for the high score is the relatively recent reference point, so scores reflect changes that have taken place in only about three decades. The trend for habitats is negative for many places, so their high score is no basis for undue optimism. Many habitats were likely already significantly degraded by the ~1980 reference point date and restoring them to their state in earlier times does not seem possible now. However, restoring them to their ~1980 states is feasible and would significantly benefit many aspects of the human-ocean system. 

A further reason why scores might seem too optimistic to some is that the Index rescaled biodiversity scores linearly, assuming that each additional species at risk or amount of habitat lost corresponds to an equivalent change in the Status score. In reality, people may consider initial losses of species or habitats much worse than when systems are already degraded or heavily at risk. For those with such a value system, Index scores may seem too optimistic.