Garbage collection in Costa Rica. (Rodrigo Arangua/AFP/Getty Images)

Solid waste management is almost always the responsibility of local governments and is often their single largest budget item, particularly in developing countries. Solid waste management and street sweeping is also often the city’s single largest source of employment.

That’s from the World Bank’s new “What a Waste” report, which estimates that 1 to 5 percent of the world’s urban population is employed in some form of solid-waste management — that includes everyone from workers at recycling plants to the more than 2 million informal “waste-pickers” in poorer countries.

And the garbage will keep piling up. Currently, the world spends $205.4 billion to handle about 1.3 billion tons of trash each year. (That's about 2.6 pounds per person per day.) Yet the World Bank expects the world’s solid waste to swell to 2.2 billion tons per year by 2025, largely driven by rapid growth in poorer countries like China and India. And the costs of trash are expected to quadruple or quintuple in many low-income countries.

In developing countries, the World Bank warns, all that fast-growing garbage is a real problem because “uncollected solid waste contributes to flooding, air pollution, and public health impacts such as respiratory ailments, diarrhea and dengue fever.”

More broadly, garbage contributes about 5 percent of the world’s greenhouse gases, especially as organic matter in landfills decomposes and produces methane, a major contributor to global warming. Efforts to promote recycling, curb waste, and capture methane from landfills could help there.

“Improving solid waste management,” the report notes, “especially in low income countries, is an urgent priority.”