A failure to address the mountains of waste in the developing world will result in as much plastic in our oceans as fish, the head of Ocean Conservancy has warned.

Andreas Merkl, CEO of the Washington-based environmental NGO, said the combination in the developing world of a burgeoning middle class and low recycling rates will lead to an exponential rise in the amount of plastic washed out to sea.

If governments and the private sector fail to solve this problem, “we end up with an ocean that has an amount of plastic that’s in the same order of magnitude as the amount of fish, in terms of tonnes”, Merkl told Guardian Sustainable Business.

“We have enormous uncertainty about what that actually means, but it is a situation where you cannot call yourself an ocean conservationist or any person that cares about the ocean and find that even remotely acceptable.”

There are currently estimated to be around 800m tonnes of fish in the oceans and 100m to 150m tonnes of plastic. This is increasing by around 20m tonnes a year, but that growth is expected to accelerate as far greater numbers of people are able to afford to buy products that are made with, or packaged in, plastic.

Plastic is not just harming the marine environment, but also providing a huge economic cost to fishermen and tourism, Catherine Novelli, US undersecretary of state for economic growth, energy and the environment, said at a private meeting at the World Economic Forum in Davos, Switzerland, last week.

Novelli said the problems were becoming particularly acute in regions – such as parts of Asia – that have a huge middle class, but trash collection of only around 40%, compared with 95% in the US.

Pointing to the circular economy – the idea of turning trash into raw materials for new products – as one of the key solutions, she said: “We need to have a real economic analysis of the entire supply chain and target what needs to be done and work with friendly governments and cities to show what practically can be done. You have to bring it to reality otherwise everyone despairs.”

It’s important for business leaders and policy makers to come out of their separate silos and work together on solutions, Novelli said, adding that there is an opportunity to partner with big and influential countries like China and India to redesign the world economy.

“We all have the same issues of what is threatening us,” she said. “There are different perspectives, but that is all to the good.”

In the search for practical solutions, the Trash Free Seas Alliance, a collaboration between industry and NGOs, is planning to carry out detailed studies in three or four countries, with a particular emphasis on Asia.

Merkl says the plan is to “really dig into the economics of collection and recycling so that people will find it profitable to collect and to separate. The fact is that even at a scavenger economy level of daily wages, recycling these types of plastics are currently not worthwhile, which is why so much just ends up going in the ocean. The question, then, is how do we fundamentally change that.”

He said it was disingenuous to seek a ban on non-recyclable flexible plastic, like cellophane, as it is an “enormous accelerator in lifestyles”. Not only does wrapping food reduce the spread of typhoid, but single-use containers gives people access to clean water.

Fortunately, Merkl said the issue is starting to rise up the political agenda, helped by the sight of giant gyres of marine debris and by people from the developed world going on beach holidays and finding plastics clinging to their bodies.

There is also growing concern about the toxicity of fish that end up eating small fragments of plastic, which they mistake for plankton.

It’s a health issue,” Merkl said. “It’s an equity issue. It’s a land pollution issue and it’s an ocean pollution issue. “For example, between 50m to 60m individual sachets of water are thrown away every day in Nigeria alone. If you go to Lagos, they’re drowning in sachets and they are clogging the drainage system.”

While improving collection and recycling is the quickest way to drive change, Merkl insisted that plastics companies and consumer goods firms also must act decisively.

“We would love to see a simplification of the plastics used,” he said. “We’d like to see less colour and an end to gluing sleeves of advertising around plastic containers. So there’s a bunch of design work that we can do and is very, very important.”

Ellen MacArthur, who broke the world record for the fastest solo circumnavigation of the globe and is now a leading activist in creating a circular economy, also said changes in all sectors of society are needed.

She is encouraging private companies and cities to collaborate to ensure that “everything has value to the economy in the future” and does not just get thrown away.

Bill McDonough, the US designer and author who believes we can design materials, systems, companies and products that continuously improve over time, said the Chinese were starting to take the lead in turning the circular economy from an idea into reality.

McDonough, the co-creator of the cradle-to-cradle design concept, said the authorities in Beijing are currently moving from “promoting the circular economy to implementing it”.

We need to design things that are valuable for next use and stop using the words ‘end of life’,” he said. “Being less bad is not being good. We need to start from the mindset of what would plastics look like if the ocean is fabulous.”

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