News

Important Lessons from the Clean Waters Goal

Clean Waters is one of the ten goals evaluated by the Ocean Health Index. At first glance the Clean Waters goal seems pretty simple. The ocean should be clean, with no pollution from chemicals, excessive nutrients, pathogens or trash. If pollution is present, clean it up.

Ahh…but that isn’t so easy. The ocean is enormous. Once contaminants enter it, it’s not possible or affordable to remove them by technological means.  In short, we can’t just raise the world’s Clean Water scores (“78,” with “100” being sustainable) by treating the ocean’s 1.3 billion km³ of water, extracting the hundreds of kinds of chemicals known or suspected to be harmful, removing excessive amounts of nutrients, disinfecting coastal waters to kill pathogenic bacteria, or straining all the plastic particles out of the ocean. No way. The only way we can achieve clean waters is to prevent pollutants from entering the ocean. 
 
“Inside the Trash Pollution Component” summarizes the method for computing Clean Water scores as a geometric average of pollution intensity from four components (chemicals, excessive nutrients, pathogens and trash); and explains that the reference point (target) was to have zero pollution. It also explains that we had to estimate pollution using related ‘proxy’ data and mathematical models, because direct measurements of pollution do not exist in all countries.

The index uses data that indicate the amount of marine trash, the intensity of pollution by chemicals (harmful organic and inorganic substances of many kinds); the amount of excessive nitrogen and phosphorus that cause overgrowth of algae and dead zones; and the concentration of pathogens (disease-causing bacteria, parasites and viruses from sewage outflow). 

Some Countries Score High, Some Score Low

These days, every country has its unique challenges in limiting pollution. Industry, agriculture, living and leisure all produce contaminants. Country by country, the Index shows a wide range of scores around the world. Russia, for example, comes in #1 in Clean Water, with a score of "97." Benin, in West Africa, ranks the lowest with “22."

In this article, we’re going to take a look at the highest and lowest scores, and explore how the four components and other geographical and socioeconomic factors help explain those scores. We’ll also look at what the results tell us about how to achieve Clean Waters.

The average score for the 10 countries with the top Clean Waters scores (92) was more than twice as high for the 10 with lowest scores (44).

Four broad measures contribute to the score: status (the amount of pollutants present compared to the target of zero pollution); trend (the percentage rise or fall of status scores over the past 5 years); pressures; and resilience (actions countries take to reduce pressures).  A country can only make progress if its resilience scores are larger than its pressures score. 

Top scoring countries achieved that, with an average resilience score of 78 that more than doubled their average pressure score (35). Bottom scoring countries did not, as their average resilience score of 53 was only 62% of their average pressure score of 86

What Factors Affect the Scores

We wanted to see what factors might explain why countries scored the way they did and whether they could provide guidance on how scores might be improved.   

For example, the countries listed differ in some obvious ways:  geographic size, population size and coastline length, for example. Did those factors influence scores?  Or could we identify other factors that did?    

The first step in our analysis was to compile a spreadsheet listing the countries and their attributes (see below). The data were run in a statistical program to identify any factors that are significantly related to the scores. We used linear regression tests to see how much of the variation in scores was explained by each factor and whether the relationship was statistically significant, i.e. would occur by chance less than 5% of the time). We also tested the relative importance of chemicals, nutrients, pathogens and trash in determining scores (rank correlation).  

Scores were not significantly affected by a country’s geographic size (km²), total population size or population living within 25 km of the coast, coastline length or area (km²) of its Exclusive Economic Zone or EEZ, the waters from the shore out to 322 km (200 mi). 

We found that scores were weakly positively related to the ratio of length of coastline to country area (coastline per km²).  That is, countries with long coastlines relative to their size (islands, for example) tended to have higher scores.  One reason for this may be that a number of small islands in the list had high scores, probably because they are uninhabited and located in remote oceanic regions where several of the pressures may be reduced. On the other hand, countries such as Russia and Canada--which have very long coastlines--also scored well because these northerly countries have large arctic sections with long coastlines that are nearly uninhabited, and because they manage water quality well in more populous sections.   

Scores for all four types of pollution were closely linked, with very strong relationships between scores for chemicals and excessive nutrients; and between pathogens and trash. All the other combinations were moderately strongly correlated, with the weakest linkage between scores for excessive nutrients and trash. These correlations seem reasonable, since chemicals and nutrients both mainly originate from urban or rural industry, agriculture and human was disposal and enter via rivers and run-off from land; whereas pathogens and trash both originate from areas with high population. The fact that agriculture, erosion and other nutrient sources are broadly distributed, whereas trash is more closely linked with human population centers probably explains the weaker correlation between nutrients and trash.  

Environment, Education and Health Matter the Most

The Index factor most strongly related to scores was cumulative environmental pressures. The Clean Waters goal is unique because the four categories of contaminants measured are used to indicate both status and pressures. That pressures explained about 87% of the differences between scores, and did so with a very high degree of statistical significance, was to be expected. Cumulative resilience measures---estimated for this goal as a country’s score on the World Governance Indicators (WGI) as a proxy for being able to take actions to reduce pollution--- explained less of the score differences (37%) and with moderate significance.

We wanted to explore whether socioeconomic differences might explain the scores for the 20 countries analyzed.  For comparison we chose a measure that was not used in the Ocean Health Index and could provide an independent scale for comparison, namely the Human Development Index (HDI). Created by the UN Development Project (UNDP), HDI ranks countries on the basis of education (years of schooling for adults 25 years and older, and expected years of schooling for children entering school); health (life expectancy at birth); and wealth (decent standard of living, measured as Gross National Income corrected for price purchasing parity. The geometric average of the scores for education, health and wealth yield the HDI score, which ranges from 0 to 1.00, by which countries are ranked. 

The relationship between countries’ performance on HDI and scores for the Clean Waters goal was strongly positive and significant. HDI scores and ranks explained more than 60% of the differences in countries’ scores, strongly suggesting that the better a country scores on HDI, the higher its Clean Waters score is likely to be. The 10 countries that scored highest for Clean Waters had an average HDI score of 0.789 and an average HDI rank of 55, compared to an average HDI score of 0.500 and average HDI rank of 148 for the 10 countries with lowest Clean Waters scores.  Thus there is a meaningful (and inverse) statistical relationship between human development and ocean pollution.  Other analyses show that this relationship also held for countries’ overall scores on the Ocean Health Index.  

Why is human development so important to clean water and ocean health? Everything we do is a potential source of ocean pollution including how we produce energy, what we manufacture, what we do with wastes from energy and manufacturing processes, what we buy and how we use and dispose of those products and packaging, what we eat and how we grow it….the list is endless. Doing everything sustainably requires good education. Without it, people can’t understand the overall problem and can’t learn how to take the necessary care at every step so that no more pollutants will reach air, land, lakes, rivers and eventually the ocean. But good education can’t happen without good health and a decent standard of living. Poverty, poor health care and short life expectancy make it difficult to provide and obtain good education. So nurturing human well-being is essential to keeping pollutants from entering the ocean and the surest way to achieve long-term progress toward clean water.

By itself, clean ocean water isn’t of any direct use to people (i.e. we don't drink sea water), but it enables and supports nearly all of the benefits that the ocean can provide and that are evaluated in the other goals of the Ocean Health Index. Thus, clean waters form the strong foundation needed for a healthy ocean.

In the end, scores for the Clean Waters goal tell us much more than just how much toxin and trash is in the ocean.  They teach us about ourselves and the need to work together to develop healthy, sustainable societies. We can’t have healthy oceans without them.

Click here to view an Ocean Health Index video on Clean Waters.

A note on finding country rankings in the Index:

To access country rankings in every goal, go to a goal page and click on the map titled "Country Rankings."  The top ten countries will appear. From this screen, you can click on "Rank" to get the bottom ten countries. If you click on "Score," the same result will appear. Clicking on "Country" will arrange the countries in alphabetical order. "Show More" will give you the entire list of 171 countries or EEZ's. If you want to see country rankings in another goal, pull down the menu from the goal name. It's not currently possible to search just by country name.