Posted on behalf of Mark Zastrow.

Google’s fleet of city-mapping cars are now working to measure urban natural gas leaks.

The technology giant’s collaboration with the Environmental Defense Fund (EDF), announced on 16 July, equips Google’s Street View cars with sensors to detect methane leaking from ageing city pipes, through city streets and into the atmosphere. The sensors were developed by researchers at Colorado State University in Fort Collins.

The project has released online methane maps for Boston, Massachusetts; Staten Island in New York; and Indianapolis, Indiana. The team found thousands of leaks in Boston and Staten Island at a rate of roughly one per every mile (1.6 kilometres) of road driven, whereas Indianapolis’s roads are leaking only once every 200 miles (322 kilometres) — a sign of newer infrastructure.

These leaks are too small to be a health or explosion risk, but they are also a growing climate concern; methane is 86 times more powerful as a greenhouse gas than carbon dioxide, over a 20-year period, according to the Intergovernmental Panel on Climate Change. Massachusetts passed legislation in June that requires utilities to speed up their pipe replacement, and California is considering following suit.

“We think [this technique] will offer a new way for utilities and regulators to evaluate their ongoing leak detection and repair programs,” says Mark Brownstein, the leader of the EDF’s natural gas efforts. The group says that utilities could reduce their emissions 2–3 times faster by prioritizing those larger leaks.

But just how utilities might actually use the data in practice remains to be seen, says Susan Fleck, vice-president of pipeline safety for National Grid, a London-based private utility that is also collaborating on the mapping project. “You know, I just have to be really up front about this. This is a pilot programme, right? So it’s kind of hard to say exactly how this is going to work out,” she told reporters.

Nathan Phillips, an ecologist at Boston University in Massachusetts, is sceptical that the data will help utility operators identify specific leaks. Phillips’ team pioneered car-borne urban methane mapping in Boston and has a separate project funded by the EDF, but is not involved with the Google effort. He points out that utilities already know from their own records where the ageing and leak-prone cast iron pipes are. “It doesn’t take a lot of guesswork to say, ‘There’s a 120 year old pipe running under this street, it’s probably a leaky street.’”

What excites him are the project’s plans to go nationwide and the opportunity to compare data across cities. Already, he says he is struck by how few leaks Indianapolis has compared to Boston and Staten Island, a sign of its newer infrastructure. He wonders if publicly owned gas networks (such as that of Indianapolis) will prove less leaky than those owned by private companies that need to balance expansion and market share with maintenance of existing infrastructure; it’s the type of question ‘Big Data’ could answer.

“That’s the beauty of what Google and EDF are getting into,” he says. “This is just a kind of teaser.”

Blueberries are rich in ‘nutritionally desirable’ antioxidants. {credit} Amanda Mills/CDC{/credit}

Organic produce certainly costs more than conventionally grown food, but is it better for you?

Evidence so far has suggested that there are no health benefits from eating organic food instead of conventionally grown produce. Now a review of the scientific literature concludes that organic consumers may be getting their money’s worth; it claims that organic food is more nutritious than conventionally grown fodder.

Researchers led by Carlo Leifert, who studies ecological agriculture at Newcastle University, UK, found that organic food contains significantly higher levels of “nutritionally desirable” antioxidants compared to conventional crops. For example, phenolic acids, flavanones and flavonols were 19%, 69% and 50% higher, respectively, in organic produce than in its conventional counterparts, says the study, which was published today in the British Journal of Nutrition.

The researchers also found that organic produce contains lower amounts of pesticide and lower concentrations of cadmium, a metal that can build up in the body through repeated exposure and become toxic. “There are significant composition differences between organic and conventional crops for a range of nutritionally relevant compounds,” they write.

The study finds that eating organic food could boost a person’s antioxidant intake by up to 40% — the equivalent of two portions of fruits or vegetables a day. This could provide “meaningful” benefits to human nutrition, the authors write, because many antioxidants have been linked to a lower risk of chronic diseases, including certain cancers. Still, Leifert told Nature that his team has “no evidence of what the potential health impact may be”.

Leifert says that the study is an improvement on earlier analyses because it includes a larger data set — 343 peer-reviewed studies — making its results more robust.

A 2009 review on behalf of the UK Food Standards Agency (FSA) in London looked at total of 67 studies on the nutritional content and health effects of organic and conventional produce. This study found no clear nutritional benefits of organic produce over conventionally grown food. Likewise, a review of 237 studies published the Annals of Internal Medicine in 2012 also found no significant differences.

Alan Dangour, a food and nutrition scientist at the London School of Hygiene and Tropical Medicine and lead author of the FSA review, told Nature that the latest study suffers from significant problems with its methods and analysis. It shows “no important differences in nutrient content between organically and conventionally produced food”, he says, adding that the paper includes many studies of varying quality, which affects the reliability of its results.

Leifert says that Dangour was “too selective” in the quality of research he chose to include in the FSA study and consequently omitted important information. He says that his team conducted an additional analysis on a more selective group of studies but found that their results and conclusions still largely confirmed nutritional differences between organic and conventional produce.

Other researchers also criticized the paper. Richard Mithen, a food and health researcher at the Institute of Food Research in Norwich, UK, said in a statement that there is no evidence that the small differences that the researchers found in the levels of antioxidants would have any consequences for public health. And Tom Sanders, a nutritional scientist at King’s College London, says that nothing in the study changes his view that there are no meaningful nutritional differences between conventional produce and organic crops.

Climate change is not a distant threat but has “moved firmly into the present”, according to a US government report released today.

Rising greenhouse gas emissions have made US summers longer and winters shorter, increased the risk of some extreme weather events and raised sea levels, finds the 1,300-page analysis, compiled by 300 scientists. It is the United States’ third national assessment of climate change impacts, following similar reports in 2000 and 2009.

“This national climate assessment is the loudest and clearest alarm bell to date signalling the need to take urgent action to combat the threats to Americans from climate change,” says John Holdren, President Barack Obama’s science advisor and director of the White House Office of Science and Technology Policy.

Overall, the average US temperature has increased by 0.7-1.0 degrees Celsius since 1895, with the pace of warming quickening after 1970. The mercury is poised to rise another 1.1-2.2 degrees Celsius within the next few decades. And by the end of the century, it could reach sizzling temperatures 2.8-5.6 degrees Celsius hotter than today’s conditions, unless the world commits to major reductions in greenhouse gas emissions.

Such changes are already affecting how Americans live and work, warns the report, which examines climate change impacts at the regional and state levels. In the Pacific Northwest, spring is starting earlier, changing the timing of snowmelt and in turn reducing water supplies in summer. In Alaska, receding sea ice is exposing large swathes of the state’s coast to erosion, prompting some coastal villages to plan costly relocations. And the Northeast has seen a 70% increase in the amount of rain falling as heavy downpours, increasing the region’s risk of flooding.