Mercury pollution is a global problem with local consequences: Emissions from coal-fired power plants and other sources travel around the world through the atmosphere, eventually settling in oceans and waterways, where the pollutant gradually accumulates in fish. Consumption of mercury-contaminated seafood leads to increased risk for cardiovascular disease and cognitive impairments.

In the past several years, a global treaty and a domestic policy have been put in place to curb mercury emissions. But how will such policies directly benefit the U.S.? 

The amount of methane gas escaping from the ground during the long cold period in the Arctic each year and entering Earth's atmosphere is likely much higher than estimated by current carbon cycle models, concludes a major new study led by San Diego State University and including scientists from NASA's Jet Propulsion Laboratory, Pasadena, California.

The study included a team comprising ecologists Walter Oechel (SDSU and Open University, Milton Keynes, United Kingdom) and Donatella Zona (SDSU and the University of Sheffield, United Kingdom) and scientists from JPL; Harvard University, Cambridge, Massachusetts; the National Oceanic and Atmospheric Administration, Boulder, Colorado; and the University of Montana, Missoula. The team found that far more methane is escaping from Arctic tundra during the cold months when the soil surface is frozen (generally from September through May), and from upland tundra, than prevailing assumptions and carbon cycle models previously assumed. In fact, they found that at least half of the annual methane emissions occur in the cold months, and that drier, upland tundra can be a larger emitter of methane than wet tundra. The findings challenge critical assumptions in current global climate models. The results are published this week in the Proceedings of the National Academy of Sciences.

Do not underestimate the babbling brook. When it comes to greenhouse gases, these bucolic water bodies have the potential to create a lot of hot air. According to a new analysis in the journal Ecological Monographs, by researchers at the University of Wisconsin–Madison and colleagues, the world’s rivers and streams pump about 10 times more methane into our atmosphere than scientists estimated in previous studies.

Drivers are seeing more hydrogen fuel cell electric vehicles (FCEVs) on the road, but refueling stations for those vehicles are still few and far between. This is about to change, and one reason is a new testing device being validated at California refueling stations that will greatly accelerate station commissioning.

Developed by U.S. Department of Energy’s (DOE) Sandia National Laboratories and the National Renewable Energy Laboratory (NREL), the Hydrogen Station Equipment Performance device, or HyStEP, could reduce the time to commission new stations from months to just one week. HyStEP is funded by DOE’s Office of Energy Efficiency and Renewable Energy’s Fuel Cell Technologies Office as part of the Hydrogen Fueling Infrastructure Research and Station Technology (H2FIRST) project.

2015 has marked the International Year of Soils, an event that many members of the public missed — but they shouldn’t have, because soil is vitally important for human survival. Ominously, a study from the Grantham Centre for Sustainable Futures indicates that in the last 40 years, humans have chewed through 33 percent of the Earth’s topsoil, thanks to development and harmful farming practices. The grim findings are a bad sign for the future, as we rely on soil not just for sustenance, but also as a carbon trap, key component of nearly every ecosystem on Earth, and breeding ground for organisms with tremendous commercial and humanitarian applications, such as bacteria that could contribute to the development of cutting edge pharmaceuticals. We should be worshiping the ground we walk on, and this study indicates that we’ve been doing just the opposite.

Climate negotiators meeting here in Paris have achieved a deal that could change the world. Conference chair and French foreign minister Laurent Fabius crowed that he had presided over a "historical turning point." Even when the hype has died down, that may turn out to be true. Even climate scientists who on Friday had sharply criticized an earlier draft of the text were convinced.  

The Paris Agreement commits the world to capping global warming to "well below 2 degrees Celsius above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees C." To achieve that, it requires the world to "reach global peaking of greenhouse gas emissions as soon as possible" and "to undertake rapid reductions thereafter, in accordance with best available science." 

Lawrence Livermore researchers and collaborators have found that most climate models overestimate the increase in global precipitation due to climate change.

Specifically, the team looked at 25 models and found they underestimate the increase in absorption of sunlight by water vapor as the atmosphere becomes moister, and therefore overestimate increases in global precipitation.

The team found global precipitation increase per degree of global warming at the end of the 21st century may be about 40 percent smaller than what the models, on average, currently predict.

Is Paris the beginning of the end for coal? Coal burning is declining fast in both of the world's two largest carbon dioxide emitters, China and the the United States, with resulting declines in the emissions of both countries. The fuel looks incompatible with a world that warms by no more than two degrees Celsius, bringing calls for its rapid phaseout as the world is "decarbonized." 

But, with or without a deal here in Paris later this week, will the calls be heeded? Has the demise of King Coal been greatly exaggerated?  

In the U.S., "coal has gone from boom to bust," says Michael Brune, executive director of the Sierra Club. The black stuff's share of electricity generation has sunk from 53 percent to 35 percent in just five years.
 

Taking a deep breath might be a bit harder for children exposed early in life to a widely used class of pesticides in agriculture, according to a new paper by UC Berkeley researchers.

The greater the pesticide exposure, the smaller the lungs, a new study finds.

As representatives from more than 190 countries convene in France for the second week to address ways to slow global warming, an MIT-led team has published a paper outlining a set of options for incorporating equity considerations in a national Emissions Trading System (ETS) for China that could reduce carbon emissions while minimizing economic impact on poorer or less-developed regions.

The paper, “Equity and Emission Trading in China,” published in the journal Climatic Change, outlines a sophisticated menu aimed at Chinese policymakers showing how the burden of reducing carbon emissions could be shared or divided across the country’s provinces under a market-based carbon pricing system.

“Emission trading systems have been shown to be highly effective when they are allowed to work, but one of the toughest challenges involves how to distribute the cost,” said lead author Valerie Karplus, Assistant Professor of Global Economics and Management at the MIT Sloan School of Management. “We compare alternative schemes for allocating emissions rights that can effectively de-couple who pays for reductions from where the reductions actually occur.”