Green Economy in a Blue World-Full Report

nutrient economy could generate clearly would run into many tens of billions of dollars given the breadth and scale of the concerned sectors (see Section 3.2). 2.1 Ocean nutrient pollution sectors Over the last 20 years, significant data and experience in understanding and addressing the sectoral drivers, pressures, sources, impacts and response to reactive nitrogen have been gathered and progress made in trying to address these issues. The key sectors that are involved include the agriculture, waste-water management, and fertilizer production sectors. As shown in the figure to the right for the year 2000, models indicate that globally, roughly equal amounts of reactive nitrogen reach the oceans from fertilizer, manure and (dominantly anthropogenic) atmospheric deposition, with smaller fractions from sewage and agricultural nitrogen fixation. However, analysis

in a Blue World

Nitrogen sources to watershed exports to the oceans

25 Megatonnes of Nitrogen per year

Predicted

20

15

10

5

0

1970

2000

2030 GO 2030 AM

Sewage

Natural N 2 fixation Manure

Fertilizer Deposition

Agriculture N 2 fixation

Note: GO is Global Orchestration scenario, AM is Adapting Mosaic scenario

Source: Seitzinger et al ., 2010

at the regional level shows somewhat different proportions with sewage less important in less developed continents such as Africa, South Asia and South America, suggesting the need to apply nutrient reduction strategies that best fit the nutrient profile of a given region or sub- region or basin. Not surprisingly, while business as usual model projections indicate relatively modest (30-40%) growth in nutrient emissions to the oceans from Europe and North America by 2050, these same models (figure on page 82) predict explosive growth in emissions from Africa (200%), South Asia (200%), South America (200%) and East Asia (100%) which would lead to significant increases in eutrophication and coastal hypoxia in each of these regions where many of the economies of coastal and island states have a particularly high dependence on marine ecosystem goods and services. Coastal eutrophication driven by excess nutrient burdens can lead to substantial environmental degradation including hypoxia (“dead zones”) and has emerged as one of the principal environmental challenges facing the sustainability of marine ecosystems and the livelihoods and economies that depend on these ecosystems. Due to the roughly threefold increase in nitrogen burdens from continents to oceans since pre-industrial times, the incidence of hypoxic zones has been increasing at a geometric rate in recent years and is projected to 2.2 Environmental and social challenges and opportunities

continue to accelerate inmost of the developing world in business as usual scenarios (figure on page 82). The global socio-economic impacts at the present time are already many hundreds of billions of dollars and these impacts will only increase further, especially in the developing world, if new nutrient management paradigms are not soon put into place. There is also ample evidence (such as in the Black Sea with the comb jellyfish Mnemiopsis) that marine ecosystems already weakened by hypoxia may be more susceptible to the successful introduction of aquatic invasive species which can further disrupt ecosystem function and stability. There is also increasing scientific evidence that hypoxic conditions act as endocrine disruptors (Wu, et al., 2003) affecting reproductive success of marine organisms including decreased size of reproductive organs, low sex hormone levels, low egg counts and reduced spawning activity. 2.2.1 Description of the sectors as a business Agriculture The advent of agriculture dates back several thousand years so is arguably one of the oldest economic sectors in human history which, by creating food surpluses which allowed humans to shift away from hunter-gatherer societies, is widely credited with hastening the development of human civilization. After the overall service sector, today agriculture is the world’s largest employer with roughly

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