New York City endured another brutal summer this year, and you know what that means: a severe urban heat island effect and the omnipresent stench of rotting garbage. Summer in New York makes one acutely aware of the near-constant presence of waste piling up on pavements waiting to be collected and trucked to an out-of-state landfill.

New York is, in fact, widely reported to be the world’s most wasteful city. Wastefulness in this case means New York uses the most energy (“the equivalent of one oil supertanker every 1.5 days”), disposes of the most trash (33m tonnes per year), and uses the most water. The dubious title comes from a study published last spring in Proceedings of the National Academy of Sciences (PNAS).

While the world’s most wasteful city could well be in the consumption-rich US, New York is an unlikely culprit. If the world’s most wasteful city is American, as it very well may be, it’s probably a sprawling sunbelt metropolis like Houston, Atlanta, Tampa, or Phoenix – all of which rate worse than New York on most environmental metrics but weren’t included in that particular study.

Among global megacities, Mexico City generates the most trash after the New York region: 12m tonnes per year. That’s largely a function of relative wealth: the regions have similar population sizes of just over 20 million and 21 million people respectively, but GDP per capita is three times higher in the US.

But waste is a bigger quality of life problem in Mexico. At least the steaming trash in New York is being put out for the sanitation trucks. In 2011, Mexico City closed its largest dump, causing trash to pile up at illegal dumping sites and be left out on the street, highlighting the absence of a comprehensive policy for urban waste collection, disposal and processing. There are signs of hope, though. A number of recycling initiatives have been launched, including one that allows residents to trade in recyclables for vouchers to purchase fresh fruits and vegetables.

The third biggest waste producer among megacities is Tokyo, which is actually impressively austere. Greater Tokyo has more than 50% more residents than Mexico City, but it produces slightly less rubbish. Japan is very densely populated, and so it lacks the space that the US and China have to throw their garbage in landfills. Instead, they have adopted hyper-aggressive recycling programmes to cut down on waste. Tokyo, which strives to be a zero-waste city, is no exception.

The wealthier a place is, the more is wasted and thrown. Alex Kovac, World Resources Institute

So how can Tokyo be rated the third most wasteful city? This is the tricky thing about measuring wastefulness: waste is a byproduct of consumption, and consumption generally tracks with income. “There are some general rules for consumption levels: as income rises, people just cycle through more consumption patterns in general,” says Alex Kovac, a research analyst at the World Resources Institute, an international environmental research organisation. “The wealthier a place is, the more is wasted and thrown.”

A city’s waste rate, Morton says, roughly follows that of the country it’s in. According to a World Bank study from 2012, the most recent on the subject, New Zealand generated the most garbage, 3.68kg per person every day, among developed countries, followed by Ireland, Norway, Switzerland, and the US. But the data on smaller countries may be failing to account for recycling.

Norway, for example, has high rates of recycling and Oslo, its largest city, has successfully reduced its waste production in recent years. Ireland, on the other hand, has lower recycling rates than in the rest of western Europe. Dublin might be one of the most wasteful cities in Europe, but it is still only a second-tier competitor for world’s most wasteful city, as its greenhouse gas emissions are still only half the rate of the US or Australia.

Tokyo is densely populated, so doesn’t have the space for landfills. Photograph: Yuya Shino/EPA

The US is the world’s biggest producer of trash in absolute terms, generating 624,700 metric tonnes per day, which is 2.58kg/capita. That’s considerably more than many other rich countries, such as Japan’s 1.71kg/capita, the UK’s 1.79kg and France’s 1.92kg.

According to a 2010 study by the water bottle company Nalgene – which measured self-reported behaviours such as using public transportation, recycling, and conserving electricity – the five most wasteful of the US’s 25 largest cities are Houston, Cleveland, Atlanta, Tampa and Indianapolis, in that order. Nalgene found New York was found to be the third least wasteful, after San Francisco and Seattle. (On the subject of water waste, Phoenix, which is built in a desert, devotes half of its residential water use to irrigate lawns.)

In China, waste is growing twice as fast as the population. As the Globe and Mail notes, China now produces an average of 1.12kg per person per day of residential waste, nearly 10% more than the average in Ontario, even though China’s GDP per capita is more than six times lower. Chinese cities don’t recycle, meaning that their waste output could be cut in half, as it has been in neighbouring Taiwan.

China doesn’t break out its waste data by city, but some Chinese cities with notable refuse problems include Beijing, Guangzhou, and Shenzhen, which have started building trash incinerators to pick up the slack from a shortage of landfill capacity. But burning trash, in turn, just worsens their notoriously dirty air. Guangzhou has also started charging households that exceed 1 litre of rubbish per day.

A garbage collector in Beijing. Some Chinese cities have started burning waste, worsening air pollution. Photograph: Kim Kyung-Hoon/Reuters

Which cities have the worst waste problem also depends on how they dispose of it. Most wasteful as measured by total garbage created, will knock out almost all developing world cities, for the simple reason that they cannot afford to buy and waste as much. But if you’re talking about some of the local problems associated with trash, like having it piling up in your streets, some of the world’s poorest cities, such as Manila and Port-au-Prince, have very big problems indeed.

Without the infrastructure to collect garbage, it’s dumped in rivers, canals and streets, and the result is unsanitary chaos. Other developing cities that are overburdened with trash they cannot process include those with fast-growing economies such as Bangalore and Delhi.

Mumbai produces the fifth most waste of any megacity, and last year Bloomberg reported it was “being buried under a mountain of its own trash”. The city of over 18 million people produces 11,000 metric tonnes of trash per day. Plastic wrappers and bottles fill the gutters, backyard waste burning contributes to air pollution, and the rest winds up in a giant open landfill.

In Delhi, which experienced a 50% increase in waste between 2007 and 2012, the lack of formal trash pick-up systems leads to rubbish mountains and impoverished waste pickers sorting through it for anything that can be reused or resold. Delhi’s garbage problem and its overwhelming smog could certainly make it the world’s dirtiest city.

Men scavenge for coins and re-usable items in the Yamuna river in New Delhi, India. Photograph: Prakash Singh/AFP/Getty

Rapid population growth itself may also be a risk factor. Jakarta, for example, is one of the world’s fastest growing cities and many of its residents are in the habit of dumping their household items in the nearest waterway. So much makes its way out to sea that 100 tonnes of garbage a day is collected on the beaches of an island five miles away.

Even a rich city can find it impossible to stash away all its waste if it’s too tightly packed. Hong Kong is on the precipice of running out of space in its landfills. A decade ago, Singapore had the same problem, but it implemented policies to boost recycling and burn trash for energy. Now it puts only 2% of its waste in landfills. That’s not without its own drawback: burning rubbish creates air pollution, from carbon emissions to toxins and particulates.

Cairo’s trash problem is unique: not only does it produce 625 kg per person per year of solid waste – a very high rate for a poorer country – but its system of trash pickers, and feeding waste to pigs, have been disrupted by political instability, religious disapproval of pigs by the temporary Muslim Brotherhood government and an outbreak of swine flu.

Whichever of these cities is truly the world’s most wasteful, New York probably doesn’t take the crown after all. The 2015 study titling it thus misleadingly measured its metropolitan region, rather than the city itself. New York City’s metro region includes large swathes of suburbia and satellite cities spread across three states. What’s more, the study only took into account megacities over 10 million people, leaving out a whole host of incredibly wasteful smaller cities.

Throughout the United States, suburbanites have much larger carbon footprints than those who live in the centre of a city. That discrepancy is very pronounced in New York, thanks to the city’s unusually high share of non-drivers and relatively small homes. New York City also has aggressive recycling programmes that are currently expanding beyond paper, metals, and plastics to compost food waste.

The greater density, more pedestrian-oriented urban planning, and vastly superior mass transit networks in Europe and Japan make their cities and suburban towns much more energy efficient than most of the US. Waste charging schemes like “pay as you throw”, food waste projects, widespread recycling, ultimately policies committing to zero waste, are just some of the ways in which cities can become a lot less wasteful. That, and cutting consumption.

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