The Human Fossil-Fuel Addiction: Greenhouse Emissions Soar to Record Levels

How can we stop? Credit: Shutterstock

After a few promising years of minimal carbon-emission growth, the world is on pace to burn a bunch more fossil fuels. According to a new estimate, global carbon emissions will hit a record-breaking 37.1 billion metric tons in 2018.

That’s a 2.7 percent increase over 2017’s global emissions output of 36.2 billion metric tons, researchers with the Global Carbon Project reported Dec. 5. And 2017’s numbers represented a 1.6 percent increase over the year before.

“For three years, we saw flat greenhouse gas emissions at the same time [that] the world economy grew. That was good news,” said Robert Jackson, a professor of Earth system science at Stanford University. “We hoped that represented peak emissions. It didn’t.” [The Reality of Climate Change: 10 Myths Busted]

To turn off the emissions spigot, countries will have to focus on renewable energy, and quickly, Jackson said.

Rising emissions
Climate change is already underway. A 2010 NASA study found that Earth’s average surface temperature rose 1.44 degrees Fahrenheit (0.8 degrees Celsius) over the 20th century. The Arctic, in particular, is responding rapidly to this change, exhibiting record levels of melt. Surface meltwater from Greenland alone now contributes nearly a millimeter of global sea-level rise to the oceans each year.

In October, the United Nations Intergovernmental Panel on Climate Change warned that the world will have to slash carbon emissions to 45 percent below 2010 levels by the year 2030 and then halt all emissions by 2050 in order to keep global average temperatures from rising more than 2.7 degrees F (1.5 degrees C).

A graph showing carbon emissions from land use and fossil fuel burning (top) and where all that spare carbon has settled (bottom). Carbon in the atmosphere (blue) warms the globe; carbon in the oceans (dark green) causes acidification that can harm marine animals. Credit: The Global Carbon Project, Le Quéré et al, Earth System Science Data 2018

Currently, emissions are headed in the wrong direction, Jackson and his team found. Between 2017 and 2018, China is estimated to have increased its carbon output by 4.7 percent. The U.S. output has risen about 2.5 percent in the same period. India saw the sharpest increase in carbon output between 2017 and 2018, at an estimated 6.3 percent. The European Union has increased its outputs as well, by 0.7 percent.

The drivers of these trends are both meteorological and economic, the researchers reported. An especially cold winter in the eastern United States and a hot summer across the country increased fossil fuel emissions from the heating and cooling of homes and other structures. A decline in the price of oil led to the purchase of larger cars and trucks in the United States. Meanwhile, a sluggish economy in China has leaders there incentivizing heavy industry and instituting coal-power projects that had been on hold, Jackson said. Economic development in India has that nation scrambling to build any energy project it can.

“They’re building coal, nuclear and renewables at breakneck pace,” Jackson said. “Every coal plant they build is likely to be polluting 40 years from now.”

Turning it around
Despite the sobering trends, there are glimmers of hope. The United States and Canada have seen a decrease in coal consumption of about 40 percent since 2005, Jackson said. And despite the vocally pro-coal administration of president Donald Trump, some 15 gigawatts of coal plants are slated to close this year in the U.S., a potential record, Jackson added.

“The pricing for wind and solar is now competitive with [that of] fossil fuels in many cases,” Jackson added.

Although developing countries like India and China are rapidly growing their fossil fuel emissions, developed nations like the United States and the countries of the European Union are still responsible for the majority of emissions. Credit: The Global Carbon Project, 2018

The transportation sector is a bigger challenge, Jackson said, as low oil prices lead consumers to drive more frequently and buy larger vehicles. Incentivizing electric vehicles — which can be charged with power generated by clean energy — would make a big impact in emissions, Jackson said.

Globally, the picture is complex. India, for example, is striving to bring any electric power at all to millions of people who have none.

“They need financial incentives to reduce reliance on new coal plants” and to build renewable-energy infrastructure instead, Jackson said.

Though it’s discouraging to see emissions rising so quickly, Jackson said, he’s an optimist at heart. “I believe green energy will eventually win,” he said. The only question is how much warming will have to occur first and how hard it will be to rein in today’s excesses.

“The higher we go in emission today,” Jackson said, “the faster or the deeper the cuts need to be in a decade or two decades or beyond.”

Jackson and his colleagues on the Global Carbon Project published their estimates on Dec. 5 in the journals Environmental Research Letters and Earth System Science Data.

Car tires and brake pads produce harmful microplastics

These particles can end up in bodies of freshwater and, eventually, the ocean

TREAD LIGHTLY Tiny pieces from rubber tires, brake pads and asphalt make up most of the airborne microplastic pollution around three German highways, a study finds.

TREAD LIGHTLY Tiny pieces from rubber tires, brake pads and asphalt make up most of the airborne microplastic pollution around three German highways, a study finds.

There’s a big problem where the rubber meets the road: microplastics.

Scientists analyzed more than 500 small particles pulled from the air around three busy German highways, and found that the vast majority — 89 percent — came from vehicle tires, brake systems and roads themselves. All together, these particles are classified by the researchers as microplastics, though they include materials other than plastic.

Those particles get blown by wind and washed by rain into waterways that lead to the ocean, where the debris can harm aquatic animals and fragile ecosystems, says environmental scientist Reto Gieré of the University of Pennsylvania. He presented the findings on November 6 at the annual meeting of the Geological Society of America in Indianapolis. Previous research has estimated that about 30 percent of the volume of microplastics polluting oceans, lakes and rivers come from tire wear.

“We all want to reduce CO2 emissions” from vehicle exhaust, Gieré says. “But you can’t stop tire abrasion.” Traffic congestion makes the problem worse. Vehicles traveling at constant speeds, without so much brake use, produced fewer particles, the researchers found.

Because some materials, including synthetic rubber, become coated in dust and other tinier bits of debris, they’re not always easy to identify. The researchers figured out what each particle was by examining each of them under a scanning electron microscope and running chemical analyses.

“These [tire] particles are stealthy,” says John Weinstein, an environmental toxicologist at the Citadel in Charleston, S.C., who was not involved in the study.

Engineers are plugging holes in drinking water treatment | Access to clean water still isn’t universal

New tech solutions

These three new water-cleaning approaches wouldn’t require costly infrastructure overhauls.

Ferrate to cover many bases

Reckhow’s team at UMass Amherst is testing ferrate, an ion of iron, as a replacement for several water treatment steps. First, ferrate kills bacteria in the water. Next, it breaks down carbon-based chemical contaminants into smaller, less harmful molecules. Finally, it makes ions like manganese less soluble in water so they are easier to filter out, Reckhow and colleagues reported in 2016 in Journal–American Water Association. With its multifaceted effects, ferrate could potentially streamline the drinking water treatment process or reduce the use of chemicals, such as chlorine, that can yield dangerous by-products, says Joseph Goodwill, an environmental engineer at the University of Rhode Island in Kingston.

Ferrate could be a useful disinfectant for smaller drinking water systems that don’t have the infrastructure, expertise or money to implement something like ozone treatment, an approach that uses ozone gas to break down contaminants, Reckhow says.

Early next year, in the maiden voyage of his mobile water treatment lab, Reckhow plans to test the ferrate approach in the small Massachusetts town of Gloucester.

In the 36-foot trailer is a squeaky-clean array of plastic pipes and holding tanks. The setup routes incoming water through the same series of steps — purifying, filtering and disinfecting — that one would find in a standard drinking water treatment plant. With two sets of everything, scientists can run side-by-side experiments, comparing a new technology’s performance against the standard approach. That way researchers can see whether a new technology works better than existing options, says Patrick Wittbold, the UMass Amherst research engineer who headed up the trailer’s design.

NICE WHEELS Patrick Wittbold, UMass Amherst quality assurance manager, helped design the Mobile Water Innovation Laboratory (left), a trailer that will test new drinking water technologies around Massachusetts. Inside the van is a flexible setup of filters, pipes and chemicals (right).

NICE WHEELS Patrick Wittbold, UMass Amherst quality assurance manager, helped design the Mobile Water Innovation Laboratory (left), a trailer that will test new drinking water technologies around Massachusetts. Inside the van is a flexible setup of filters, pipes and chemicals (right).

Charged membranes

Filtering membranes tend to get clogged with small particles. “That’s been the Achilles’ heel of membrane treatment,” says Brian Chaplin, an engineer at the University of Illinois at Chicago. Unclogging the filter wastes energy and increases costs. Electricity might solve that problem and offer some side benefits, Chaplin suggests.

His team tested an electrochemical membrane made of titanium oxide or titanium dioxide that both filters water and acts as an electrode. Chemical reactions happening on the electrically charged membranes can turn nitrates into nitrogen gas or split water molecules, generating reactive ions that can oxidize contaminants in the water. The reactions also prevent particles from sticking to the membrane. Large carbon-based molecules like benzene become smaller and less harmful.

In lab tests, the membranes effectively filtered and destroyed contaminants, Chaplin says. In one test, a membrane transformed 67 percent of the nitrates in a solution into other molecules. The finished water was below the EPA’s regulatory nitrate limit of 10 parts per million, he and colleagues reported in July in Environmental Science and Technology. Chaplin expects to move the membrane into pilot tests within the next two years.

Obliterate the PFAS

The industrial chemicals known as PFAS present two challenges. Only the larger ones are effectively removed by granular activated carbon, the active material in many household water filters. The smaller PFAS remain in the water, says Christopher Higgins, an environmental engineer at the Colorado School of Mines in Golden. Plus, filtering isn’t enough because the chunky chemicals are hard to break down for safe disposal.

Higgins and colleague Timothy Strathmann, also at the Colorado School of Mines, are working on a process to destroy PFAS. First, a specialized filter with tiny holes grabs the molecules out of the water. Then, sulfite is added to the concentrated mixture of contaminants. When hit with ultraviolet light, the sulfite generates reactive electrons that break down the tough carbon-fluorine bonds in the PFAS molecules. Within 30 minutes, the combination of UV radiation and sulfites almost completely destroyed one type of PFAS, other researchers reported in 2016 in Environmental Science and Technology.

Soon, Higgins and Strathmann will test the process at Peterson Air Force Base in Colorado, one of nearly 200 U.S. sites known to have groundwater contaminated by PFAS. Cleaning up those sites would remove the pollutants from groundwater that may also feed wells or city water systems.

Filter and destroy

An electrochemical membrane filters out contaminants like a traditional membrane. As a bonus, it also breaks down contaminants via chemical reactions on the membrane’s surface.

water membrane

Engineers are plugging holes in drinking water treatment

DRINKABILITY  Researchers are testing new ways to bring affordable water treatment to smaller towns and to people who rely on wells.

DRINKABILITY Researchers are testing new ways to bring affordable water treatment to smaller towns and to people who rely on wells.

Off a gravel road at the edge of a college campus — next door to the town’s holding pen for stray dogs — is a busy test site for the newest technologies in drinking water treatment.

In the large shed-turned-laboratory, University of Massachusetts Amherst engineer David Reckhow has started a movement. More people want to use his lab to test new water treatment technologies than the building has space for.

The lab is a revitalization success story. In the 1970s, when the Clean Water Act put new restrictions on water pollution, the diminutive grey building in Amherst, Mass. was a place to test those pollution-control measures. But funding was fickle, and over the years, the building fell into disrepair. In 2015, Reckhow brought the site back to life. He and a team of researchers cleaned out the junk, whacked the weeds that engulfed the building and installed hundreds of thousands of dollars worth of monitoring equipment, much of it donated or bought secondhand.

“We recognized that there’s a lot of need for drinking water technology,” Reckhow says.  Researchers, students and start-up companies all want access to test ways to disinfect drinking water, filter out contaminants or detect water-quality slipups. On a Monday afternoon in October, the lab is busy. Students crunch data around a big table in the main room. Small-scale tests of technology that uses electrochemistry to clean water chug along, hooked up to monitors that track water quality. On a lab bench sits a graduate student’s low-cost replica of an expensive piece of monitoring equipment. The device alerts water treatment plants when the by-products of disinfection chemicals in a water supply are reaching dangerous levels. In an attached garage, two startup companies are running larger-scale tests of new kinds of membranes that filter out contaminants.

BACK TO LIFE David Reckhow and his colleagues at UMass Amherst have renovated an old building into a new lab to test the latest drinking water treatment technology.

BACK TO LIFE David Reckhow and his colleagues at UMass Amherst have renovated an old building into a new lab to test the latest drinking water treatment technology.

Parked behind the shed is the almost-ready-to-roll newcomer. Starting in 2019, the Mobile Water Innovation Laboratory will take promising new and affordable technologies to local communities for testing. That’s important, says Reckhow, because there’s so much variety in the quality of water that comes into drinking water treatment plants. On-site testing is the only way to know whether a new approach is effective, he says, especially for newer technologies without long-term track records.

The facility’s popularity reflects a persistent concern in the United States: how to ensure affordable access to clean, safe drinking water. Although U.S. drinking water is heavily regulated and pretty clean overall, recent high-profile contamination cases, such as the 2014 lead crisis in Flint, Mich. (SN: 3/19/16, p. 8), have exposed weaknesses in the system and shaken people’s trust in their tap water.

Tapped out

In 2013 and 2014, 42 drinking water–associated outbreaks resulted in more than 1,000 illnesses and 13 deaths, based on reports to the U.S. Centers for Disease Control and Prevention. The top culprits were Legionella bacteria and some form of chemical, toxin or parasite, according to data published in November 2017.

Those numbers tell only part of the story, however. Many of the contaminants that the U.S. Environmental Protection Agency regulates through the 1974 Safe Drinking Water Act cause problems only when exposure happens over time; the effects of contaminants like lead don’t appear immediately after exposure. Records of EPA rule violations note that in 2015, 21 million people were served by drinking water systems that didn’t meet standards, researchers reported in a February study in the Proceedings of the National Academy of Sciences. That report tracked trends in drinking water violations from 1982 to 2015.

New rules boost violations

The Safe Drinking Water Act regulates levels of contaminants in public water supplies. This graph tracks violations of the act over time. Spikes in violations often coincide with new, more stringent rules.



Current technology can remove most contaminants, says David Sedlak, an environmental engineer at the University of California, Berkeley. Those include microbes, arsenic, nitrates and lead. “And then there are some that are very difficult to degrade or transform,” such as industrial chemicals called PFAS.

Smaller communities, especially, can’t always afford top-of-the-line equipment or infrastructure overhauls to, for example, replace lead pipes. So Reckhow’s facility is testing approaches to help communities address water-quality issues in affordable ways.

Some researchers are adding technologies to deal with new, potentially harmful contaminants. Others are designing approaches that work with existing water infrastructure or clean up contaminants at their source.

How is your water treated?

A typical drinking water treatment plant sends water through a series of steps.

First, coagulants are added to the water. These chemicals clump together sediments, which can cloud water or make it taste funny, so they are bigger and easier to remove. A gentle shaking or spinning of the water, called flocculation, helps those clumps form (1). Next, the water flows into big tanks to sit for a while so the sediments can fall to the bottom (2). The cleaner water then moves through membranes that filter out smaller contaminants (3). Disinfection, via chemicals or ultraviolet light, kills harmful bacteria and viruses (4). Then the water is ready for distribution (5).

There’s a lot of room for variation within that basic water treatment process. Chemicals added at different stages can trigger reactions that break down chunky, toxic organic molecules into less harmful bits. Ion-exchange systems that separate contaminants by their electric charge can remove ions like magnesium or calcium that make water “hard,” as well as heavy metals, such as lead and arsenic, and nitrates from fertilizer runoff. Cities mix and match these strategies, adjusting chemicals and prioritizing treatment components, based on the precise chemical qualities of the local water supply.

Some water utilities are streamlining the treatment process by installing technologies like reverse osmosis, which removes nearly everything from the water by forcing the water molecules through a selectively permeable membrane with extremely tiny holes. Reverse osmosis can replace a number of steps in the water treatment process or reduce the number of chemicals added to water. But it’s expensive to install and operate, keeping it out of reach for many cities.

Fourteen percent of U.S. residents get water from wells and other private sources that aren’t regulated by the Safe Drinking Water Act. These people face the same contamination challenges as municipal water systems, but without the regulatory oversight, community support or funding.

“When it comes to lead in private wells … you’re on your own. Nobody is going to help you,” says Marc Edwards, the Virginia Tech engineer who helped uncover the Flint water crisis. Edwards and Virginia Tech colleague Kelsey Pieper collected water-quality data from over 2,000 wells across Virginia in 2012 and 2013. Some were fine, but others had lead levels of more than 100 parts per billion. When levels are higher than its 15 ppb threshold, the EPA mandates that cities take steps to control corrosion and notify the public about the contamination. The researchers reported those findings in 2015 in the Journal of Water and Health.

To remove lead and other contaminants, well users often rely on point-of-use treatments. A filter on the tap removes most, but not all, contaminants. Some people spring for costly reverse osmosis systems.

Contaminants to keep out of the tap

Microbes: Untreated water can host harmful bacteria and viruses.

By-products of disinfection: Disinfectants such as chlorine and bromine can clear water of dangerous microbes. But these chemicals can react with other molecules to form dangerous by-products such as toxic chloroform.

Industrial chemicals: Per- and polyfluoroalkyl substances, or PFAS, widely used to make nonstick coatings and firefighting foams, are a large group of industrial chemicals that are hard to remove from drinking water and hard to track.

Arsenic: Arsenic is a concern for the 14 percent of U.S. residents who draw their drinking water from private wells instead of public water systems. Arsenic occurs naturally, but can also get into groundwatervia agriculture or mining.

Nitrates: Nitrates enter water supplies largely through runoff from farms and fertilized lawns. In excess, the chemicals can prevent red blood cells from carrying oxygen through the body.

Lead: The EPA mandates that cities adjust water chemistry to minimize the amount of lead that leaches from pipes into tap water, but those corrosion-controlling measures are not foolproof.

Half a degree stole the climate spotlight in 2018


Climate change intensified Hurricane Florence’s rains, which caused the Waccamaw River in South Carolina to overflow.

The grim reality of climate change grabbed center stage in 2018.
This is the year we learned that the 2015 Paris Agreement on global warming won’t be enough to forestall significant impacts of climate change. And a new field of research explicitly attributed some extreme weather events to human-caused climate change. This one-two punch made it clear that climate change isn’t just something to worry about in the coming decades. It’s already here.

This looming problem was apparent three years ago when nearly all of the world’s nations agreed to cut greenhouse gas emissions to limit global warming to no more than 2 degrees Celsius over preindustrial times by 2100 (SN: 1/9/16, p. 6). That pact was hard-won, but even then, some scientists sounded a note of caution: That target wouldn’t be stringent enough to prevent major changes.

So the United Nations took an unprecedented step. It commissioned the Intergovernmental Panel on Climate Change to examine how the world might fare if global warming were limited to 1.5 degrees instead of 2 degrees. That report, released in October, confirmed that half a degree can indeed make a world of difference (SN: 10/27/18, p. 7). A half degree less warming means less sea level rise, fewer species lost due to vanished habitats and fewer life-threatening heat, drought and precipitation extremes (SN: 6/9/18, p. 6).

There’s little time to reverse course. The IPCC report notes that the planet’s average temperature has already increased by nearly 1 degree since preindustrial times, and that rise is contributing to extinctions, lower crop yields and more frequent wildfires. At the end of 2017, three attribution studies for the first time determined that certain extreme events, including an extended marine heat wave in the Pacific Ocean known as “the Blob,” would not have happened without human-induced climate change (SN: 1/20/18, p. 6).

Less is more

Capping global warming at 1.5 degrees Celsius above preindustrial levels rather than 2 degrees can soften climate impacts.

Impact 1.5 degrees 2 degrees
Global average sea level rise by 2100




Increase in ocean acidity by 2100



Probability of an ice-free Arctic Ocean in the summer for any given year



Increase in the annual maximum daily temperature




Proportion of global population facing at least one severe heat wave every five years



Global population exposed to severe drought




Global population exposed to flooding in coastal areas by 2095


million per year


million per year
Proportion of species losing >50% of range that has a climate they can tolerate









Source: IPCC 2018

This year, researchers reported that the 2017 Atlantic hurricane season got a boost from warm waters in the tropical Atlantic, fueled by climate change (SN Online: 9/28/18). And a team of scientists determined that climate change was the engine behind September’s intense rainfall from Hurricane Florence in the Mid-Atlantic region of the United States (SN Online: 9/13/18).

A report released November 23 by hundreds of U.S. climate scientists from 13 federal agencies put a price tag on many of the effects for the United States (SN Online: 11/28/18). The report predicts the country’s economy will shrink by as much as 10 percent by 2100 if global warming continues on its current trajectory.

Climate simulations suggest that Earth will reach the 1.5 degree threshold within a decade. And even if countries were to agree to limit warming to that level, the planet would almost certainly surpass it before the warming reversed, due to the realities of how quickly emissions can be reduced. Passing that target will probably lead to some irreversible changes, such as melted glaciers and species losses. To overshoot the mark by only a small amount, or not at all, requires reducing emissions by about 45 percent relative to 2010 levels by the year 2030. The planet would then be able to reach net zero, when the amount of carbon released to the atmosphere is balanced by the amount removed, by around 2050, the IPCC report notes.

To bring warming back down below the 1.5 degree target by the end of the century, the world will need negative emissions technologies to remove large amounts of carbon dioxide from the atmosphere. Such technologies that limit or even reverse warming are less pie-in-the-sky than they sound, says Stephen Pacala, an ecologist at Princeton University. “Although there is a lot of doom and gloom available on the progress of humanity, there isn’t on the technological side.” Pacala chaired a National Academies of Sciences, Engineering and Medicine committee that released a report in October that analyzed the viability of current and emerging negative emissions technologies as well as encouraged large-scale investments in them.

Some simple negative emissions practices already in use include planting forests to soak up atmospheric carbon, or growing plants for biofuels and then storing underground the CO2 from the burning of those fuels. But current efforts have drawbacks. Planting sufficient forests or biofuel crops “would have a large land footprint,” says economist and IPCC coauthor Sabine Fuss of the Mercator Research Institute on Global Commons and Climate Change in Berlin. And that could impact future food availability and biodiversity.

alternatives to fossil fuels.

To limit global warming, communities need to embrace alternatives to fossil fuels. In Iceland, Reykjavik Energy has a pilot project to directly capture carbon dioxide from the air at a geothermal power plant (shown).

Other negative emissions technologies in development could become game changers, Pacala says. Direct air capture, in which CO2 is removed directly from the atmosphere and converted into synthetic fuel, is a proven technology. But so far, the high cost of direct air capture remains a barrier to commercial-scale development. The National Academies report says that nations should subsidize start-ups to drive competition in this area — after all, that’s what worked for wind and solar power, Pacala notes. Other proposed negative emissions technologies, such as converting atmospheric CO2 into a stable mineral form (SN: 9/15/18, p. 9), show some promise but require large-scale financial investment in their basic science to make them viable, the report states.

Reducing demand for resource-intensive products will also be important to reach the 1.5 degree target, Fuss says. Cities need to move away from fossil fuels, and individuals can do their part by, for example, traveling less (SN: 6/9/18, p. 5), eating less meat (SN: 7/7/18, p. 10) and installing more energy-efficient appliances. Data show that, given the right incentives, people are willing to make such lifestyle changes, says IPCC report coauthor Linda Steg, an environmental psychologist at the University of Groningen in the Netherlands. And those incentives aren’t necessarily financial or based on self-interest, she adds. “People are also motivated by protecting the interests of others, or by the quality of the environment.”

Holding warming to 1.5 degrees “is not impossible,” says Natalie Mahowald, a climate scientist at Cornell University and an IPCC report coauthor. But “it really requires ambitious efforts, and the sooner the better. We have to start cutting emissions now.”

Political will to act varies country by country, but scientists have done what they can to convey the urgency and the scope of the climate change problem, says IPCC report coauthor Heleen de Coninck, an environmental scientist at Radboud University in Nijmegen, Netherlands. Nations “have it in their hands, and they know what they are working with,” de Coninck says. “Now it’s up to them.”