Clear The Air News Blog Rotating Header Image

January, 2017:

Scientists disprove there was a hiatus in global warming after confirming controversial study

http://www.telegraph.co.uk/science/2017/01/05/scientists-disprove-hiatus-global-warming-confirming-controversial/

A reported pause in global warming between 1998 and 2014 was false, according to US-British research published Wednesday that confirmed the findings of a controversial US study on ocean warming.

Scientists at the University of California, Berkeley, and the University of York, England, corroborated the results of the National Oceanic and Atmospheric Administration’s (NOAA) research paper in 2015.

Their findings were reported in the US journal Science Advances.

The NOAA paper had shown ocean buoys now used to measure water temperatures tend to report slightly cooler temperatures than older ship-based systems.

The switch to buoy measurements had hidden some of the real-world warming during the 1998-2014 period, the NOAA scientists concluded.

The NOAA paper had drawn outrage from some scientists who insisted there had been a “global warming hiatus” and from critics who consider global warming a hoax.

The US House of Representatives, controlled by the Republican Party, had even demanded the NOAA scientists provide lawmakers with their email exchanges about the research.

The US government agency agreed to transmit data and respond to scientific questions but refused to hand over the emails of the study’s authors, a decision supported by scientists worried about political interference.

“Our results mean that essentially NOAA got it right, that they were not cooking the books,” said Zeke Hausfather, a graduate student in UC Berkeley’s Energy and Resources Group and lead author of the new study.

The International Panel on Climate Change, in a report published in September 2013, said the average global warming between 1951 and 2012 had been 0.12 degrees Celsius (0.22 degrees Fahrenheit) per decade.

But between 1998 and 2012, warming had amounted to only 0.07 degrees Celsius per decade, indicating a ‘global warming hiatus.’

The 2015 NOAA analysis, which was adjusted to correct for the “cold bias” of buoy measurements, found there was no detectable slowdown in ocean warming over the previous 15 years.

Reporting in the journal Science, the NOAA scientists said the oceans has actually warmed 0.12 degrees Celsius per decade since 2000, nearly twice as fast as the earlier estimates of 0.07 degrees Celsius per decade.

That brought the rate of ocean temperature rise in line with estimates for the previous 30 years, between 1970 and 1999.

The new study uses independent data from satellites and Argo floats, a worldwide satellite-based location and data collection system, as well as from buoys.

The information gathered confirmed the NOAA results in 2015 were correct, the scientists said.

“We were initially skeptical of the NOAA result, because it showed faster warming than a previous updated record from the UK Met Office,” said Kevin Cowtan of the University of York.

“So we set out to test it for ourselves, using different methods and different data. We now think NOAA got it right, and a new dataset from the Japan Meteorological Agency also agrees,” he said.

Hong Kong enjoys a breath of fresh air but it’s not enough to meet annual quality goals

Lower concentrations of harmful pollutants were recorded last year but roadside-dominant nitrogen dioxide remains a headache for the city

Lower concentrations of harmful pollutants were recorded last year, including the tiny particulates that can penetrate deep into the lungs – but roadside- dominant nitrogen dioxide remains a headache for the city, with most figures failing annual air quality targets.

And while ambient concentrations of hazardous ozone fell for the second consecutive year, they are proving stubbornly hard to cut having increased 15 per cent since 1999.

The preliminary air quality data for 2016 was released by the Environmental Protection Department yesterday.

At roadsides, concentrations of respirable suspended particulates (PM10) dropped by 15 per cent, fine suspended particulates (PM2.5) by 12 per cent, and sulphur dioxide
(SO2) by 10 per cent.

Similar drops were recorded at general stations. Fewer hours and days of high health risk air were recorded at both ambient and roadside stations last year.

But although roadside concentrations of nitrogen dioxide (NO2) – a product of fuel combustion – fell by 17 per cent, the average annual concentration of 82 micrograms per cubic metre of air was still more than double the annual air quality objective target of just 40.

All three roadside monitoring stations also fell short of the air quality objectives for acceptable annual NO2 levels last year.

“Roadside NO2 remains a very big challenge as reduction technologies available now are not that sophisticated,” assistant director of air policy Mok Wai-chuen said.

At roadsides, concentrations of respirable suspended particulates (PM10) dropped by 15 per cent, fine suspended particulates (PM2.5) by 12 per cent, and sulphur dioxide
(SO2) by 10 per cent.

Similar drops were recorded at general stations. Fewer hours and days of high health risk air were recorded at both ambient and roadside stations last year.

But although roadside concentrations of nitrogen dioxide (NO2) – a product of fuel combustion – fell by 17 per cent, the average annual concentration of 82 micrograms per cubic metre of air was still more than double the annual air quality objective target of just 40.

All three roadside monitoring stations also fell short of the air quality objectives for acceptable annual NO2 levels last year.

“Roadside NO2 remains a very big challenge as reduction technologies available now are not that sophisticated,” assistant director of air policy Mok Wai-chuen said.

He believed improvements in particulate pollution were a result of policy measures such as an ongoing scheme to phase out old diesel commercial vehicles progressively and new laws requiring ships at berth to switch to low- sulphur fuel.

“This proves our policies to tackle particulate matter have been effective,” he said, adding that other measures such as tightening emission controls are being looked at.

Mok claimed the most severely polluted days were a result of ozone, a regional problem, either from pollution blowing in from the Pearl River Delta or meteorological
conditions such as tropical cyclones.

Ozone is formed through a reaction of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the air and under sunlight. It is a main component of photochemical smog – which gives a dusk sky a lurid, orange tint – and at elevated levels, can cause or aggravate respiratory diseases.

Asked if the toxic smog plaguing northern China could have drifted south, he said “it could not be ruled out” but “was of low possibility”.

The Clean Air Network’s Loong Tsz-wai said Mok’s meteorological explanations diverted attention from the most pressing issue, which was roadside pollution and the
“uncontrolled growth” of road vehicles.

“Most of our exposure to bad air is at roadside,” he said. “NO2 concentrations may be going down but the effectiveness of exhaust pipe policies could be easily offset over the years if the number of private cars is not curbed.”

Wang Tao, chair professor of atmospheric environment at Polytechnic University, said the increase in regional ozone had indeed slowed since 2013, but not fallen. More control of precursors, such as VOC and NOX, were needed on both sides of the border, he said.

Source URL: http://www.scmp.com/news/hong-kong/healthenvironment/article/2059691/hong-kong-enjoys-breath-fresh-air-its-not-enough

High-Speed Train Caked in God Knows What Reveals How Bad China’s Air Has Gotten

Images of a high-speed train that traveled 497 miles between Shanghai and Beijing reveals just how polluted China’s air really is.

http://nextshark.com/high-speed-train-china-airpocalypse/

The photos show that the train has got caked-on grime all over, presumably as a result of the PM2.5 air quality.

The photos show that the train has got caked-on grime all over, presumably as a result of the PM2.5 air quality.

Share Tweet Images of a high-speed train that traveled 497 miles between Shanghai and Beijing reveals just how polluted China’s air really is. train_through_smog The photos show that the train has got caked-on grime all over, presumably as a result of the PM2.5 air quality. train_through_smog2 “This is what our lungs look like as well,” one netizen said of Beijing’s now infamous “airpocalypse,” according to the Shanghaiist.

“This is what our lungs look like as well,” one netizen said of Beijing’s now infamous “airpocalypse,” according to the Shanghaiist.

train_through_smog4

However, more photos below shows China’s train-cleaning crews hard at work keeping the high-speed trains looking nice and pristine for the next group of passengers.

However, more photos below shows China’s train-cleaning crews hard at work keeping the high-speed trains looking nice and pristine for the next group of passengers.

The railway line connecting Beijing and Shanghai was opened to the public in July 2011 by the Chinese ministry of railways, reported the International Business Times.

The fare for the journey ranged from $63 to $279 depending on the speed and seat category. Speeds of China Railway High-speed Harmony bullet trains’ vary from 155 to 217 miles per hour.

CEMENT EXAMINED AS A CARBON SINK

New research into the carbonation of cement could improve its environmental reputation, Kathryn Allen reports.

http://www.iom3.org/materials-world-magazine/news/2017/jan/04/cement-examined-a-carbon-sink

The recent study, Substantial Global Carbon Uptake by Cement Carbonation, headed by Professor Dabo Guan of the University of East Anglia, UK, claims that cement materials form a significant carbon sink.

Suggesting that only limited attention has been paid to the natural carbonation of cement materials when considering their environmental impact, the team used data on these materials to calculate estimated carbon dioxide (C02) uptake from 1930–2013. These estimations, at both regional and global levels, considered the life of cement materials including demolition and secondary uses.

Published in Nature Geoscience, the study found the estimated amount of carbon captured, from 1930-2013, offset 43% of the C02 emissions released from the production of cement. However, this does not include carbon emissions from fossil fuels used during production. In the same period, an estimated 4.5 gigatonnes of carbon was removed from the atmosphere through the carbonation of cement materials. Carbonation occurs when the calcium components of cement-based materials react with C02 in the air to form calcium carbonate.

When asked about the relevance of the findings, the team said they were important in the mitigation of climate change. Addressing the negative environmental impact of cement materials, the team pointed to the volume of cement being produced, as well as that already in existence, and its potential to absorb C02. The researchers claim 76 billion tonnes of cement was produced globally between 1930 and 2013, with 4 billion tonnes produced, mostly in China, in 2013 alone.

The team describes the vast volume of cement available to carbonate C02 as an overlooked carbon sink. Responding to this claim, Dr Charles Fentiman, Director at Shire Green Roof Substrates, noted that by using the term carbon sink the team ‘seems to be trying for a positive spin to suggest that concrete could somehow offset the C02 generated by burning of fossil fuels for other purposes, such as heating, cars and so on.’ In reality, the net emissions from cement materials is simply lower than previously thought.

Considering the potential to improve the environmental reputation of these materials, Dr Alan Maries, Visiting Professor in Environmental Technology at the University of Greenwich, UK, claimed that while this research may do so, ‘the global production of concrete already exceeds that of all other man-made materials combined by more than an order of magnitude in volume, [therefore] I doubt whether it will affect its use very much. What it will do, however, is take the pressure off cement manufacturers as villains.’

Maries also pointed out that ‘the extent of sequestration of carbon cement-containing materials has been calculated from compositional data and exposure conditions (rather than actually measured), then mathematically modelled making various assumptions. There appears to have been little field measurement to support the calculations.’ However, considering the distinguished authors of the study and the reliable sources of information, Maries suggests that the conclusions drawn are well supported. A similar concern was raised by Dr Andrew Dunster, Principle Consultant at BRE, whose view that the study contains assumptions on quality and exposure of concrete and the speed of carbonation of demolished materials makes him think potential over-estimations of carbonation levels have been made.

The team behind the study has, however, acknowledged that data is lacking in terms of how carbonation is affected by the environment, for example, by coatings and coverings of cement materials. They quote studies that show coatings such as paint can reduce carbonation by up to 10–30% as well as studies that refute this claim.

Carbonation correction coefficients, which are intended to reflect the possible effects of coatings, were used in this study to, in theory, produce accurate results. However, the reliance on estimations in this study has not gone unnoticed.

The researchers hope their findings can be applied practically to future developments. Buildings made of cement materials can be designed to maximize carbonation and recycling and reuse of cement materials will prevent the absorbed carbon from being released back into the atmosphere. Discussing potential applications of the findings, Guan said, ‘We suggest that if carbon capture and storage technology were applied to cement process emissions, the produced cements might represent a source of negative C02 emissions. Policymakers might also investigate a way to increase the completeness and rate of carbonation of cement waste.’

How shrinking dolphin numbers off Hong Kong’s largest island point up environmental impact assessments

City’s third runway plan, controversial bridge among projects sparking debate

On paper, residents of Kat Hing Gardens, a cluster of small village houses near Kam Sheung Road railway station in Kam Tin should have a phenomenal view – one of sprawling wetlands full of waterbirds and rare butterflies.

After all, the then Kowloon-Canton Railway Corporation (KCRC) had built them to compensate for 12 hectares of natural wetland between Kam Tin and Yuen Long that was permanently lost during the construction of the Kam Sheung Road section of the West Rail Line.

The reality however, is a fragmented collection of swamps, isolated from functional wetland systems. Some of them wither in the shade of the viaduct. Most measure just a few thousand square feet and are barricaded from the public by a hostile wall of steel and wire fencing. Apart from mosquitoes, there is minimal life. There are even times when the wetlands are not even wet at all.

“This was just compensation for the sake of compensation,” said Dr Ng Cho-nam an associate professor of geography at the University of Hong Kong. “It is meaningless.

These wetlands have no ecological value.”

The West Rail was the first large-scale project to require a managed wetland compensation project under the requirement of the project’s environmental permit, which was based on approval of its environmental impact assessment (EIA).

The example has entered Ng’s educational canon – he teaches EIA at university – as a classic case of short-sighted ecological mitigation and compensation planning as well as the shortcomings of the impact assessment system. “I bring all my students here on field trips,” Ng said.

The West Rail was built more than a decade ago. But as development projects across the city get bigger, more complex and political, critics have raised questions.

Calls for an overhaul of the EIA system have been growing in recent years, with lawmakers on the environmental affairs panel of the Legislative Council demanding that a complete review of the 18-year-old EIA Ordinance be placed on their discussion agenda this term.

“The weakest components of the EIA system are mitigation measures for ecology and the environmental monitoring and auditing [EM&A],” said Dr Michael Lau Wai-neng, assistant director of conservation at WWFHong Kong and a member of the Advisory Council on the Environment, which must vet EIA reports and make recommendations to the government.

He was referring to the chapter of the EIA technical memorandum that requires “verification of predictions or measures” to mitigate environmental impacts upon completion of the project.

Dr Gordon Maxwell, an ecologist an Open University and a former EIA appeal board member, agreed and said the ordinance needed to be enhanced as it currently “excluded more things than it included”. “It doesn’t take into account or pay attention to the ecological function,” he said. “We should be trying to enhance the ecological
quality.”

Mitigation mishaps

Coming under intense public scrutiny in recent years has undoubtedly been the city’s HK$141.5 billion third runway [3] system. It is Hong Kong’s biggest infrastructure project since the new airport was built.

Activists have slammed the issuing of an environmental permit to the Airport Authority as a breach of “procedural justice”. The EIA, they claim, had left several environmental and ecological questions unanswered but had still been approved.

A judicial review over the decision was recently thrown out by the High Court.

The judicial challengers believed there had been a lack of immediate mitigation measures in the EIA to compensate for the more than 650 hectares of permanent habitat loss – mainly to the protected Chinese white dolphin. Issues such as the accumulative impacts from surrounding projects such as the bridge connecting Hong Kong, Macau and Zhuhai had also been ignored.

One of the 250 mitigation measures was the creation of an enlarged protected marine park for dolphins – but only when the project was completed in 2023. The authority’s experts claim displaced dolphins will come back eventually but conservationists believe this is “wishful thinking”.

Spelling doom for dolphins

Dr Samuel Hung Ka-yiu, chairman of the Dolphin Conservation Society, has been one of the project’s biggest critics. He said it was disappointing the city had not learned from the experience of the EIA for the bridge. The project had also been subject to judicial review over unaddressed issues of pollution and the use of faulty methodology in
the EIA.

The project was delayed after the Court of First Instance ruled the assessment failed to meet the government’s own standards in 2011. But the government appealed and the ruling was overturned by the Court of Appeal.

Chinese white dolphin numbers in northern Lantau have tanked since construction work began in 2011, driven to waters further away or to death by deafening noise pollution and declining fish stocks.

Elaborate mitigation measures were introduced in the EIA from silt curtains to action and limit levels. But dolphin numbers are still going down and nobody can be held
responsible.

From an average encounter rate of 7.7 sightings per 100km in 2011, the figure dropped to just 1.4 in 2015. Their abundance in north Lantau has nearly halved since 2010.

Since 2015, the number of dolphins seen in northern Lantau waters has fallen by 60 per cent.

“The [bridge project] pretty much opened the Pandora’s box of easy to pass EIAs,” said Hung. His theory, he claimed, had been confirmed by the judicial decision on the runway EIA.

Hung said the biggest problem with EIA reports was that they were commissioned to “independent” consultants by project proponents and were almost always approved by the government. “Their main job is to make sure their client’s EIA is passed, not to ensure that the environment is protected,” he said, pointing out that in many cases such as in the third runway, the same consultant was hired to help do the EM&A. “The question arises: are they truly independent?”

Since the ordinance was introduced, the director for environmental protection has received 240 EIA reports. Of these, 38 had failed to either meet certain criteria or were withdrawn before consultation. Just one was rejected.

Role of gatekeeper in doubt

It doesn’t help that the gatekeeper for the EIA, the director, also holds the position of permanent secretary for the environment, a post at risk of coming under political
pressure.

“There are too many interests involved in EIAs,” said Dr Billy Hau Chi-hang, a University of Hong Kong ecologist and a member of the Advisory Council on the Environment, who has been calling for a review of the system rather than the ordinance.

“In this political environment there is always the chance of political manipulation. Even if a review of the ordinance is conducted, will it actually strengthen it?” he said.

Because most designated projects are proposed by the Hong Kong government, Hau believed it would be difficult for a director, who was also a member of the policy bureau, to split his professional and political roles in making decisions on EIAs.

The perceived conflict of interest is most apparent when it comes to government projects – the planned controversial waste incinerator on Shek Kwu Chau, for instance, was floated by the Environmental Protection Department, the body that would scrutinise and approve its EIA.

In defence of the ordinance

Those involved in EIAs, however, are quick to defend the system and brand much of the criticism as “unfair”. Built on the backs of those in the Netherlands, Australia and Canada, the system is hailed as a pioneering development for Asia that helped inspire others.

Introduced in 1998, the EIA Ordinance was seen as a way to avoid, minimise and control adverse environmental impacts from designated projects through a thorough process and a permit system. The principles were avoidance, minimisation, compensation and enhancement.

“The process has been shown to be solid over 18 years. It works, it has given the accepted result that they wanted in the legislation, and the professionalism has increased, I would say, by an order of 10,” said Dr Glenn Frommer, a former head of corporate sustainability for the MTR Corporation [6], who helped develop the assessment for the airport railway project in the early 1990s.

“Environmental protection is now a common theme. You cannot build a large scale infrastructure project in Hong Kong without having environmental professionals involved to do the adequate planning, implementation and operation.”

Clara U Kam-wa, chairwoman of the Hong Kong Institute of Environmental Impact Assessment and a senior assessor with the Environmental Protection Department, points out that over 200 EIAs have been approved since the ordinance was implemented and many developments in environmental engineering and design were adopted after being put through the EIA process. She did not believe there were conflicts of interest in the department’s dual positions as all EIAs were assessed strictly according to the technical memorandums.

“There have been so many hidden successes and unexpected consequences [of EIAs],” U said. She pointed to the influence of the Lok Ma Chau Spur Line project in altering engineering preferences from tunnels to viaducts and the evolution of excavation works to favour non-dredging methods.

In 1998, an EIA study brief set requirements on greenhouse gases at a time when climate change was not as hot a topic, influencing a decision by applicant HK Electric to opt for a gas-fired generating facility in its extension to the Lamma Island power station.

“It’s actually a very interesting story as, at that time, no one considered greenhouse gases as a pollution source,” said Freeman Cheung Chun-ming, a senior vice president for environment at engineering consultancy AECOM and a former institute chair. “They basically set the frame that new generation units would have to run on natural gas and not coal.”

Frommer highlighted two fundamental developments over the decades that EIAs will have to keep up with: the “de-siloisation” of issues set out in the memorandums and the evolution of public participation in the EIA process.

“We’re now seeing more connections between air, noise, water, waste, agricultural risk, chemical usage issues,” he said.

A frequent criticism of the ordinance has been the lax public engagement requirements.

A project proponent, for instance, is only required to consult the public and advisory council on project profiles for 14 days and on their EIA reports for one to two months.

The way forward

Conservationists like Hung believe there will be a significant “deterioration of trust” in EIAs. “After the bridge EIA was approved, I knew the third runway would finish off the dolphins,” he said. “The[project proponents] have become just too good at gaming the system.”

EIA scholars are relatively more sanguine. Ng of HKU supports “mitigation banking” – a system similar to carbon banking in which habitat loss from one project is banked as credits and used for off-site mitigation somewhere more feasible.

Source URL: http://www.scmp.com/news/hong-kong/healthenvironment/article/2058628/how-shrinking-dolphin-numbers-hong-kongs-largest

Hong Kong environment professionals call for accreditation scheme to improve impact assessment quality

With more complex development projects, institute says improved accountability is also needed

A professionals institute has called for the creation of a government-recognised chartership scheme that would accredit qualified environmental impact assessors and raise industry standards.

It comes amid increasing demand for environmental impact assessment studies as more and more complex development projects are proposed for the city.

The Institute of Qualified Environmental Professionals (HKIQEP) said the scheme would be similar to those offered by professional institutes for local surveyors, architects or engineers.

“There are many ways to substantiate your technical expertise, but under the current system there is no recognition for the environmental discipline,” institute vice-chair Freeman Cheung Chun-ming, a senior environmental manager at engineering consultancy Aecom, said.

“The purpose will be to upgrade the professional recognition of environmental professionals… to make sure members are well qualified and have a good ethics and quality.”

Cheung said the HKIQEP would be empowered by ordinance to issue Qualified Environmental Professional credentials to members who meet the experience requirements and pass a trade test and interview. Project proponents could then request to hire only those who have the relevant qualification.

He said discussions had been held with lawmakers and the government on the proposal.

The HKIQEP is made up of a number of related institutions, including the staff union for the government’s environmental protection officers.

The quality of environmental impact assessments, has come under scrutiny in recent years with multiple judicial reviews lodged against different projects, including the most recent regarding the airport’s third runway.

Over 200 environmental impact assessment studies have been approved since the ordinance came into effect in 1998.

Clara U Kam-wa, who chairs the Institute of Environmental Impact Assessment welcomed the proposed scheme.

“Accreditation doesn’t necessarily mean things will be better, but with a qualified professional, environmental consultants would be held accountable for their work,” she said.

Ecologist Dr Billy Hau Chi-hang, a member of the government Advisory Council on the Environment also commended the idea, but hoped it would improve quality control in studies.

“It’s better than nothing,” he said, questioninghow the qualification would cover such a varied field of expertise, including air and water quality, noise or ecology.
________________________________________
Source URL: http://www.scmp.com/news/hong-kong/politics/article/2058554/hong-kong-environment-professionals-call-accreditation

Review of the Draft Climate Science Special Report

Download (PDF, 1.24MB)

Hong Kong’s Climate Action Plan Report

Download (PDF, 13.68MB)

Hong Kong’s Climate Action Plan 2030+

Download (PDF, 7.1MB)

Next frontier in recycling: food

As Americans generate unprecedented volumes of garbage, much of it food and yard scraps, large-scale composting is slowly gaining traction.

http://www.csmonitor.com/Business/new-economy/2017/0101/Next-frontier-in-recycling-food

At the end of a long, rural road 22 miles east of Washington, Prince George’s County’s composting facility is chewing through thousands of tons of leaves and tree branches that are trucked in daily from across the region.

In the past three years, the county has added a new ingredient to its compost: food scraps. Pizza boxes, coffee grinds, and vegetable peels from 25 commercial customers lie in neatly piled rows on this 55-acre, open-air site. They are working through a natural digestion process boosted by hungry microorganisms and freely available oxygen from the air.

On a frigid winter day, fresh from the decomposing routine, a rich-brown, almost clay-like humus was still steaming.

“We can’t grow fast enough,” says Adam Ortiz, director the Prince George’s County Department of the Environment. The facility will double its food-processing capacity next year to accommodate 30 more customers on the waiting list, including a university and an airport, and it could grow 10-fold in the long run. “We knew that there would be interest, but we didn’t realize the amount.”

This Prince George’s facility offers a peek into the next frontier of recycling. Food and yard trimmings account for a bigger share of America’s trash than anything else – about 28 percent – slightly ahead of paper and cardboard and twice the level of plastic. And while the US recycles more than half of its yard trimmings, food composting is in its early and costly stages.

But a dearth of landfill space, friendly public policies, social pressures, and other factors are beginning to spur industrial-scale efforts to turn trashed food into something useful. For example: California, Connecticut, Massachusetts, Vermont, and Rhode Island have banned some large food producers and other large businesses, such as convention centers and supermarkets, from throwing away food, making composting a popular alternative.

Cities including San Francisco, where composting food waste has been mandatory since 2009; New York City; Austin, Texas; Cambridge, Mass.; and Milwaukee are piloting residential food composting programs. In all, more than 180 communities now collect residential food scraps up from only a handful a decade ago, according to a 2014 report from the Institute for Local Self-Reliance.

From an environmental point of view, composting is a much better option than the alternative: overstuffed landfills, often located in poor neighborhoods, where rotting food spews greenhouse gases into the atmosphere. The third largest source of United States emissions of methane, a greenhouse gas significantly more potent than carbon dioxide, are landfills, according to the US Environmental Protection Agency. If diverted from trash, compost produced from leaves, branches, and food scraps can help fertilize soil on gardens, farms, gold courses, and elsewhere.

But barriers remain to making food composting widespread.

The chicken-and-egg problem

One challenge is the chicken-and-egg problem, says Samantha MacBride, Director of Research and Operations at New York City’s Department of Sanitation. “Firms are not going to invest in plants unless there’s a guaranteed supply, but cities won’t start [composting] until they know there’s a processor” to handle the waste.

Composting food – which, if not treated properly, attracts rodents and stinks up the neighborhood – is expensive and complicated.

“It’s not like it’s a massively profitable enterprise that a lot of people are jumping into,” points out Eric Myers, Director of Organic Recycling at Houston-based Waste Management, which runs about 40 organics recycling facilities around the country.

His company also turns food waste into a sludge that municipal wastewater treatment plants, huge energy hogs, use to create electricity by harvesting the the methane that naturally comes from rotting food. This is another popular solution for discarded food.

Making compost or energy out of food scraps is still more expensive than sending trash to landfill in many regions, even in Prince George’s County. Mr. Ortiz says his composting facility is operating at a loss now, though he hopes to turn a small profit from selling compost as the facility grows.

In some places sending trash to landfill costs as little as $25 a ton, according to Mr. Myers, compared with a national average $36 a ton for composting. “That makes it a lot harder to invest time and resources” in recycling food, he says.

Cities look to flip the script

But in cities like Cambridge, which piloted in 2014 a small food recycling program that now includes 5,200 households, composting food is cheaper than trash disposal, which in New England can run up to $85 per ton.

The expensive part is hauling, says Michael Orr, recycling director for Cambridge. If enough residents divert their food from trash – right now half of the pilot households send their food scraps for composting – the city could use freed trash trucks to collect food scraps.

Milwaukee also is trying to make the composting numbers work. Its one-month-old, 500-household food-composting pilot is the latest attempt in a multiyear effort to divert recyclables from trash to meet the city’s goal of reducing garbage by 40 percent by 2020.

The city is struggling to meet the goal, in part because Milwaukee charges a flat fee for trash collection, says the city’s sanitation services manager, Rick Meyers. “If you’re paying a flat fee … there’s no incentive for people to think more critically about the materials they generate and discard,” he says. The city council has been reluctant to approve a fee structure that ties the trash cost to the amount that residents generate, though, arguing that it would burden the large population of low-income residents and exacerbate the city’s illegal dumping problem.

Despite the challenges facing food recycling, Ms. MacBride urges patience. Food composting today is where curbside recycling of glass and paper was in the 1970s when it was first introduced, she points out. “Recycling programs didn’t start up overnight; they slowly ramped up,” she says. “Give it time is really the takeaway.”