While we’ve focused plenty of attention and energy on the need for a low-carbon economy over the last several years, one big part of the picture often gets overlooked: the world’s oceans.

That’s a major oversight, considering all the sustainability challenges related to the marine environment:

• There is, of course, ever more dissolved carbon dioxide and the increasing acidity of ocean water — both effects of rising atmospheric carbon levels and both a threat to numerous species of marine life.
• Then there’s the “Great Pacific Ocean Garbage Patch,” a wide swath of trash that swirls slowly in the North Pacific Ocean Gyre. (There’s one in the Atlantic as well.)
• Now, scientists have identified yet another source of ocean pollution: “microplastics” believed to be released by synthetic-fiber clothing during washing. Wastewater with these tiny bits of polyester and acrylic “smaller than the head of a pin” eventually ends up in the world’s oceans, where that plastic appears to be entering the food chain.
• The Earth’s biosphere-ocean nitrogen cycle has also been pushed past a dangerous tipping point, with nutrient-rich runoff from fertilized agricultural lands creating more than 400 oxygen-poor “dead zones” in the world’s oceans, according to a new report from the United Nations Environment Programme (UNEP).

“A worldwide transition to a low-carbon, resource-efficient green economy will not be possible unless the seas and oceans are a key part of these urgently needed transformations,” states the UNEP report, “Green Economy in a Blue World.”

The report offers a number of recommendations for making oceans are included in the economic equation:

• Better recognition of the oceans’ ecosystem services in policy planning and investment decisions, and better pricing of ocean-based goods and services.
• Stronger ocean science to identify the many little-understood “links and dependencies in the marine environment.”
• Better regional and global frameworks to overcome limited power of individual governments to fight the “tragedy of the commons” affecting the world’s oceans.
• A move away from “brown-economy” subsidies that harm the oceans and their resources.
• An economic vision that considers not just GDP but issues like equity, security, maintenance of natural capital and other benefits to society.

“Greening our ocean economies is a challenge that needs commitment from each of us — as the individual consumer, investor, entrepreneur or politician,” the report concludes. “For countries, greening their marine economies means diversification, stronger resilience to economic or environmental shocks and sustainable prosperity.”

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