It was too perfect. And sad. On my way to see experts at Rio+20 speak about the growing waste problem in the developing world, I watched a man on his cell phone walk up to a recycling bin and dump his trash in the wrong receptacle. He walked off without even realizing what he had done.

It perfectly encapsulated the challenge. If people with access to proper recycling and waste management services aren’t using them properly, what about countries without those services?

According to experts at Rio+20, the problem is far greater than the international community is recognizing. With global municipal solid waste set to double in by 2025 — mostly in developing countries without the capabilities to manage that waste — many say it’s one of the most pressing environmental problems of our time.

“We are creating an environmental disaster that developing countries are ignoring at their own peril,” said David Newman, a board member with the International Solid Waste Association.

Less than half the world’s population has access to proper waste disposal, causing mountains of hazardous trash — including a growing amount of e-waste — to pile up. By 2020, e-waste from consumer electronics will jump 500% in some countries. That’s causing toxic chemicals to leach into groundwater and putting a financial burden on economically-constrained countries.

The United Nations has identified waste reduction strategies as a key part of its sustainable development goals. Chemical and municipal waste is mentioned frequently in the draft text that negotiators are putting together at Rio+20.

We recognize the importance of adopting a life-cycle approach and of further development and implementation of policies for resource efficiency and environmentally sound waste management. We therefore commit to further reduce, reuse and recycle waste (3Rs) as well as to increase energy recovery from waste with a view to managing the majority of global waste in an environmentally sound manner and where possible as a resource. Solid wastes, such as electronic waste and plastics, pose particular challenges which should be addressed. We call for the development and enforcement of comprehensive national and local waste management policies, strategies, laws and regulations.

While the text “recognizes” the solid waste problem and urges action through existing conventions, Newman says the international aid community doesn’t seem to be focused on the scale of the problem.

According to him, 0.25 percent of all development aid goes to helping with waste disposal strategies, or less than $400 million per year. “It’s nothing,” says Newman. “We have to raise the profile of this emergency on the international agenda. The consequences of doing nothing are disastrous.”

The World Bank issued a report on urban waste in March, finding that waste is cities around the world would grow by 100 percent by 2025. However, developing countries would face the greatest burden — with five-fold cost increases expected.

All that waste has more than just local environmental consequences. Waste disposal is responsible for 12 percent of methane, a greenhouse gas that is 20 times more potent than carbon dioxide over a 100-year period. With global waste streams set to double — more than two thirds of which will not be recycled — the global environmental consequences are stark.

“It’s madness. We’re on a downward resource spiral, yet we fail to recover 70 percent of the resources we consume. Are we crazy?” asked Newman.

Maybe that question is better asked of the man who dumped his tray of trash into the recycling bin at a global sustainability conference.