14 Jul 2014:
Human Activity Has Caused
Long-term Australian Drought, Model Shows
A new high-resolution climate model shows that southwestern Australia's long-term decline in fall and winter rainfall, which began around 1970 and has increased over the last four decades, is caused by
increases in man-made greenhouse gas emissions and ozone depletion, according to
research published in Nature Geoscience
. Simulating both natural and man-made climate effects, scientists showed that the decline in rainfall is primarily driven by human activity. Rises in greenhouse gas emissions and thinning of the ozone hole have led to changes in large-scale atmospheric circulation, including a poleward movement of the westerly winds and increasing atmospheric surface pressure over parts of southern Australia. This has led to decreased rainfall, the study said. The drying is most severe over southwest Australia, where the model forecasts a 40 percent decline in average rainfall by the late 21st century, with significant implications for regional water resources.
11 Jul 2014:
Helsinki Aims to Slash Car Use With New Apps and Transit Services
The Finnish capital is developing a new “mobility on demand” transport network
that it hopes will sharply reduce personal car use and ownership by 2025, the Guardian
reports. Helsinki officials say they will transform the existing public transportation system by using smartphone apps and new transit services that will provide convenient, relatively inexpensive, and often personalized transportation options. Central to their plan is a smartphone app that will enable users to specify a destination and then get there via a new minibus system, bike share services, ferries, trams, ride sharing, and, eventually, driverless cars. Officials say the app will serve both as a journey planner and a universal payment platform. Helsinki will expand an innovative new minibus system called Kutsuplus that lets riders specify a desired pick-up point and destinations via their smartphone; these requests are aggregated and the app calculates an optimal route that most closely satisfies the various requests.
10 Jul 2014:
A Possible Advance in Fight
To Combat a Deadly Amphibian Fungus
Scientists have discovered that a certain kind of toad can acquire immunity to the deadly chytrid fungus
, which has caused widespread mortality among amphibians worldwide. Reporting in Nature
, the scientists say they have conferred immunity in oak toads to the chytrid fungus after repeatedly exposing them to the organism that causes the disease. The lead author of the study, Jason Rohr of the University of South Florida, said the discovery means it might be possible to confer immunity on entire communities of amphibians in the wild by lacing local water sources with dead versions of the fungus that could be absorbed by the amphibians. But Rohr said many questions remain, including how long immunity lasts, what concentration of released antigen would confer immunity, and whether such releases would harm other organisms. The chytrid fungus, Batrachochytrium dendrobatidis
, attacks the skin of amphibians
, thickening it and preventing the animals from absorbing water and vital salts.
09 Jul 2014:
One-third of German Power
Came from Renewables in First Half of 2014
Thanks to abundant sunshine and wind, renewable energy generated 31 percent of Germany’s electricity
in the first six months of this year, according to a new report. The report
, released by the Fraunhofer Insititute, said that 27 percent of the country’s electricity production came from wind and solar, and four percent from hydropower. Solar power generation grew by 28 percent in the first half of 2014 compared to the first six months of 2013, and wind power grew by 19 percent over the same period. On a couple of particularly windy and sunny days in May and June, renewable energy accounted for 50 to 75 percent of Germany’s electricity production, the report said. The Fraunhofer Institute said that as Germany continues to phase out its nuclear power plants, it remains reliant on highly polluting “brown coal”
to produce electricity. A substantial portion of German coal-generated electricity is being exported, the report said.
08 Jul 2014:
Protection of Parrotfish
Could Slow Decline of Caribbean Reefs
The steady loss of coral reefs in the Caribbean could be partially reversed by taking a number of relatively simple steps, including stronger measures to protect the region’s parrotfish
, according to a new study. In a review of trends in Caribbean coral reefs
from 1970 to 2012, the Global Coral Reef Monitoring Network said that live coral only makes up about 17 percent of the region’s reef surfaces today. If present trends continue, the study said, coral reefs in the Caribbean will “virtually disappear within a few decades” because of foreign pathogens, algae invasions, pollution from tourism development, over-fishing, and warming waters. A key step in halting the decline is protecting parrotfish, which eat the algae that have been smothering coral reefs. The study said conservation measures, such as banning fish traps, have helped parrotfish populations rebound in some parts of the Caribbean, including Belize and the Bahamas.
07 Jul 2014:
A Strong Rebuke for Paper
That Forecasted `Climate Departure’
Thirteen climate scientists and meteorologists have published a sharp criticism
of a paper
by University of Hawaii biogeographer Camilo Mora, who calculated dates when earth’s climate will move into a new state caused by human-driven global warming. Mora and his ideas were featured in an interview
last week at Yale Environment 360
. In a comment article in Nature
, the 13 scientists say that Mora and his colleagues used faulty methodology that produced artificially early dates when specific regions would reach “climate departure.” They also said Mora underestimated the uncertainty involved in forecasting the time of emergence of a new climate regime. “This overconfidence could impair the effectiveness of climate risk management decisions,” the 13 scientists said in their comment. In his own comment
, Mora defended his methods, saying, “Our findings are conservative and remain unaltered in the light of their analysis.”
03 Jul 2014:
Human Activity Has Boosted
Plant Growth Globally, NASA Data Show
On a global scale, the presence of people corresponds to more plant growth, according to
an analysis of three decades of global vegetation greenness data from
Agriculture has increased global vegetative cover.
satellites. More than 20 percent of global vegetation change can be attributed to human activities, such as agriculture, nitrogen fertilization, and irrigation, rather than climate change, researchers report in the journal Remote Sensing
. The findings suggest that global climate change models, which typically don't consider human land use, should take into account the relatively large impact human settlements can have on vegetative cover, the researchers say. From 1981 to 2010, areas with a human footprint saw plant greenness and plant productivity increase by up to 6 percent, while areas with a minimal human footprint, such as rangelands and wildlands, saw almost no change. Most increases in growth and greenness were seen near rural areas and villages, where agriculture is more intense.
02 Jul 2014:
Roughly $80 Billion Wasted on
Power for Networked Devices, Report Says
The world’s 14 billion online electronic devices, such as modems, printers, game consoles, and cable boxes, waste around $80 billion in electricity annually because of inefficient technology, according to a new report
the International Energy Agency (IEA). In 2013, networked devices consumed around 616 terawatt hours (TWh) of electricity, with most of that used in standby mode. Roughly 400 TWh — equivalent to the combined annual electricity consumption of the United Kingdom and Norway — was wasted because of inefficient technology. The problem will worsen by 2020, the agency projects, with an estimated $120 billion wasted as devices such as refrigerators, washing machines, and thermostats become networked. Much of the problem boils down to inefficient “network standby,” or maintaining a network connection while in standby mode. Most network-enabled devices draw as much power in this mode as when fully active, the report notes. Using today's best technology could cut energy consumption by 65 percent, the IEA said.
Interview: Where Will the Earth
Head After Its ‘Climate Departure’?
The term “climate departure” has an odd ring, but its meaning is relatively straightforward. It marks the point at which the earth’s climate begins to cease resembling
what has come before and moves into a new state where the extreme becomes the norm. Camilo Mora — a University of Hawaii biogeographer, ecologist, and specialist in marshaling big data for climate modeling — has calculated a rough idea for the time of the earth’s climate departure: 2047. That date varies depending on region
, he says. But in a widely publicized paper published in the journal Nature
last year, Mora and 13 colleagues explored the concept of climate departure and what it will mean for our planet. In an interview with Yale Environment 360
, Mora explains why tropical regions will be most profoundly affected by climate change, why controlling population growth is at the core of the challenge posed by global warming, and the frustrations he and other scientists feel as their warnings about rising temperatures are ignored.
01 Jul 2014:
Small Island Nation of Kiribati
Purchases Foreign Land as Climate Refuge
The small island nation of Kiribati has purchased a swath of land in Fiji as a refuge for citizens who may be displaced by rising sea levels, marking the first time a
Kiribati's location (red) in the Pacific Ocean.
country has taken such actions as a defense against climate change, the Guardian reports
. Kiribati, home to 110,000 people scattered across 33 islands in the Pacific Ocean, is one of several small island nations in the Pacific and Indian oceans that could be extensively or completely submerged within a few decades. The cost of protecting such countries often far outweighs their national incomes. Kiribati, with a GDP of under $200 million, ranks among the 10 countries facing the most severe financial impacts of climate change. The tract of 20 square kilometers on the island of Vanua Levu, Fiji, could provide a future refuge for all of Kiribati's citizens, the nation's president said.
30 Jun 2014:
Antarctica's Emperor Penguins
To Be in Serious Decline By 2100, Study Says
Antarctica's Emperor penguins are facing dramatic declines by the end of the century and should be given endangered species status because of the threats posed
Sea ice loss threatens Emperor penguins.
by climate change, according to
an international group of scientists. If sea ice declines at the rates projected by current climate models, at least two-thirds of the colonies will likely shrink by more than 50 percent by 2100, the researchers report in Nature Climate Change
. That conclusion follows a 50-year study in eastern Antarctica of Emperor penguins, an iconic Antarctic species with 45 known colonies. Emperor penguins' survival is highly dependent on sea ice concentrations because they breed on the ice, and too little sea ice reduces the habitat for krill, a critical food source for the penguins. Granting the species protected status under the U.S. Endangered Species Act will provide tools for improving fishing practices of U.S. vessels in the Southern Ocean and potentially for reducing CO2 emissions in the U.S. under the Clear Air Act, the researchers say.
27 Jun 2014:
Going Vegetarian Could Halve
A Consumer’s Food-related CO2 Footprint
A new study of more than 50,000 people in the United Kingdom shows that going vegan, vegetarian, or even “pescatarian” can drastically reduce
people’s carbon footprints. Published in the journal Climatic Change
, the study concluded that if people eating more than 100 grams of meat a day went vegan, their food-related carbon footprint would shrink by 60 percent. If a person eating more than 100 grams of meat per day — and U.S. consumers eat about 225 grams daily — cut down to 50 grams per day, their food-related CO2 emissions would fall by a third, the study said. Pescatarians, who eat fish but no other meat, generate only 2.5 percent more CO2 emissions than vegetarians, according to the study. The research also concluded that vegans produce 25 percent fewer CO2 emissions than vegetarians, who still eat eggs and dairy. “In general there is a clear and strong trend with reduced greenhouse gas emissions in diets that contain less meat,” said Oxford University researcher Peter Scarborough, a co-author of the study.
26 Jun 2014:
Major U.S. Retailers to Limit
Pesticides That May Be Harmful to Bees
Home Depot and other U.S. retailers announced new policies to help limit the use of a group of pesticides suspected of contributing to widespread declines in bee
New warnings on plants aim to protect bees.
populations, Reuters reports
. Under the new rules, suppliers will be required to label any plants treated with neonicotinoid pesticides, or "neonics," that are sold in home and garden stores. Home Depot will require labeling by the fourth quarter of 2014, a company vice president said, and the retailer is testing to determine whether it's feasible to eliminate neonics altogether without compromising plant health. Another retailer, BJ's Wholesale Club, which has more than 200 East Coast locations, said it will ask suppliers to eliminate neonics by the end of the year, or label plants treated with them as requiring "caution around pollinators." An analysis of 800 peer-reviewed studies released this week by an international group of scientists found that neonics have been a key factor in bee declines
25 Jun 2014:
Blizzard Helps Scientists
Visualize Airflow Around Wind Turbines
A Minnesota blizzard has helped scientists understand airflow patterns around large wind turbines, paving the way for more efficient turbine designs and wind farm
Airflow patterns are visible during blizzard.
configurations, researchers report
in Nature Communications
. Wind farms lose roughly 10 to 20 percent of the potential energy they could harvest, and complex airflow patterns play the largest role in those energy losses. Studying airflow around large turbines, which can be more than 100 meters tall, is not feasible in lab settings, so scientists typically test smaller turbine models in wind tunnels and use tracer particles to visualize airflow patterns. Researchers from the University of Minnesota realized they could scale up their experiments to real-world conditions by using heavy snowfall during a blizzard to trace airflow patterns, as shown in this video. Their findings show that airflow patterns under real-world conditions differ from smaller-scale laboratory tests in important ways, and those differences should be taken into account when designing turbines and wind farms.
24 Jun 2014:
Concentrated Solar Power
Could Compete with Natural Gas, Study Says
Concentrated solar power (CSP) could meet a substantial percentage of current energy demand in some parts of the world, according to research
CSP plant in San Bernardino County, CA
published in the journal Nature Climate Change
. In the Mediterranean region, for example, the study shows that a grid-connected CSP network could provide 70 to 80 percent of current electricity demand, at no extra cost compared to natural gas-fired power plants. CSP could also feasibly meet energy demands in parts of southern Africa, according to researchers. CSP systems use mirrors or lenses to concentrate solar rays into a small area. The concentrated energy heats a liquid that produces steam to drive turbines, which means that the collected energy can be stored as heat and converted to electricity when needed — a major advantage over solar panels, which store energy much less efficiently.
23 Jun 2014:
How Citizen Scientists Are Using
The Web to Track the Natural World
By making the recording and sharing of environmental data easier than ever, web-based technology has fostered the rapid growth of so-called citizen scientists — volunteers who collaborate with scientists to collect and interpret data. Numerous Internet-based projects
now make use of citizen scientists to monitor environmental health and to track sensitive plant and wildlife populations. From counting butterflies, frogs, and bats across the globe, to piloting personal drones capable of high-definition infrared imaging, citizen scientists are playing a crucial role in collecting data that will help researchers understand the environment. Here is a sampling of some of these projects.
View the gallery.
20 Jun 2014:
Summer Temperatures in U.S.
Have Risen Up To 5 Degrees Since 1970
Summer temperatures in the U.S. have been rising on average 0.4 degrees F per decade since 1970, or about
2 degrees F overall, but the Southwest and West regions have borne the brunt of those increases, according to an analysis by Climate Central
. In the Southwest, temperatures have risen an average of 0.6 degrees per decade, with a few localized areas warming as much as 0.9 degrees per decade. In the West, some parts of California and Nevada have warmed 1.32 degrees F per decade, or more than 5 degrees total since 1970. On the other end of the spectrum, the Upper Midwest has seen the lowest increases. Temperatures in that region have increased only 0.1 degree F per decade on average. The National Climate Assessment
, released last month, found that annual average temperatures in the U.S. could increase by 10 degrees F before the end of the century if the rate of greenhouse gas emissions doesn't slow.
19 Jun 2014:
Rerouting Flights to Avoid
Contrails Would Slow Climate Change
Rerouting the flight paths of commercial aircraft to minimize the condensation trails, or contrails, they leave behind would help slow global warming, even if
the new flight path is longer, according to research published today
. Contrails, thin clouds composed of ice crystals condensed from an aircraft's exhaust, can persist for 17 hours or more and are likely the single largest contributor to climate change
associated with aviation. They form when a plane passes through parts of the atmosphere that are very cold and moist, usually near high pressure systems. The new research shows that avoiding contrail formation has greater climate benefits than avoiding additional carbon dioxide emissions associated with slightly longer flight routes. For example, for a small aircraft that is predicted to form a contrail 20 miles long, an alternative path that adds less than 200 miles will have a smaller climate impact than the contrail. For a larger aircraft, which emits more CO2 per mile than a smaller plane, the alternative route is preferable if it adds less than 60 miles, according to researchers from the University of Reading.
18 Jun 2014:
Global Energy Systems Must
Prepare for Climate Change, Study Says
Power plants and energy systems around the world will experience potentially disastrous effects from climate change and should develop plans for dealing with those effects, according to a report released today
by the World Energy Council and European researchers. Long-term droughts, for example, could threaten water supplies needed to cool large power plants as they produce electricity, the report notes
. Many energy facilities are also lacking protection from floods, rising seas, and severe weather events — a problem highlighted by the 2011 Fukushima nuclear disaster. Strong global political action could have major impacts on the energy sector, the report says, especially if governments make a coordinated effort to invest in renewable and low-carbon energy and upgrades to power distribution grids.
17 Jun 2014:
Livestock Maps Highlight
Regions Prone to Disease and Pollution
A new mapping tool
shows the global distribution of cattle, pigs, and other livestock in high-resolution, 1-square-kilometer detail. Created by the International
Livestock Research Institute, the Food and Agriculture Organization of the United Nations, and British and Belgian researchers, the maps are the most detailed renditions ever produced of the planet's billions of cattle, pigs, sheep, goats, chickens, and ducks. They reveal several notable trends
, such as the high density of pigs in China, India's relatively high sheep and goat populations, and the affinity of the southeastern U.S. for chickens. Researchers say they will be powerful tools for tracking and predicting livestock-borne disease outbreaks, such as avian flu strains that have been linked to dense poultry markets. The maps could also predict where major livestock operations are most likely to harm the environment, researchers say. As livestock production increases, demands on land, water, and energy intensify, and so does pollution from livestock waste
16 Jun 2014:
Skyscraper-Size Ice Structures
Discovered at Base of Greenland Ice Sheet
Melting and refreezing at the base of the Greenland ice sheet has created massive, complex structures the height of skyscrapers and the width of Manhattan, according to
research published in Nature Geoscience
The hidden formations more than a mile below the surface stand in stark contrast to the nearly flat, smooth exterior of the ice sheet and may accelerate its flow toward the sea, researchers say. Scientists had previously interpreted the irregular topography at the base of the ice as hills or mountains, but ice-penetrating radar revealed that the structures were made of ice rather than rock. Scientists from Columbia University explained that as meltwater at the bottom refreezes over hundreds or thousands of years, it radiates heat into the surrounding ice sheet, making it pick up its pace as the ice becomes softer and flows more easily. Greenland's glaciers appear to be moving more rapidly toward the sea as climate warms, but it's unclear how the refreezing process will influence this trend, researchers said.
13 Jun 2014:
U.S. Energy System Depicted
In New Mapping Tool from Federal Agency
The U.S. Energy Information Administration (EIA) recently launched a mapping system
that allows users to
explore the landscape of energy sources and power plant distribution across the nation. Among the most striking visualizations is this map showing the widespread distribution of natural gas power plants, marking the fossil fuel's growing use as an energy source. The U.S. had 1,714 natural gas power plants in 2012, accounting for 30 percent of the country's electricity generation, Vox reports
. Natural gas plants are easier to build and emit fewer pollutants and roughly half as much CO2 as coal-fired plants. The EIA maps depict numerous aspects of the U.S. power system, including the distribution of wind turbines, solar installations, nuclear power plants, coal-fired plants, hydropower stations, and pipelines. More energy maps
are available at Vox, or users can create their own with the EIA's tool.
12 Jun 2014:
U.S. Breweries Cut Water
Use Amid Widespread Drought Conditions
Major breweries in the U.S. are cutting back on the amount of water they use to brew beer as drought threatens their water supplies, the Associated Press
reports. MillerCoors, headquartered in Chicago, has reduced its water use by 9.2 percent since 2012, a company sustainability report said. Earlier this month St. Louis-based Anheuser-Busch, the largest U.S. brewer, reported that it has cut water use by 32 percent in the last five years. Employing strategies such as fueling boilers with wastewater, recycling water used to clean bottles and cans, and installing sensors to fine-tune irrigation in hop and barley fields, MillerCoors has cut water use to 3.48 barrels of water for each barrel of beer, the company says. The company is also giving $700,000 to landowners in the watershed of its Fort Worth brewery who make efforts to curb erosion and runoff by, for example, planting native grasses or rotating cattle grazing lands. Craft breweries typically use twice as much water as major breweries per barrel of beer, the AP notes, because they are smaller in scale and don't have access to the same technology.
11 Jun 2014:
Group Will Pay Farmers
To Create Temporary Migratory Bird Habitat
started by The Nature Conservancy aims to enlist California farmers in creating temporary habitats for migrating birds — a partnership that could become
more important as the state's long-term drought continues and the birds' wetland habitats dwindle. Using crowdsourced data, The Nature Conservancy (TNC) tracks the paths of migratory birds on their annual journey from Canada to South America to determine where and when the birds will need suitable wetland habitat for stop-overs in California's Central Valley. Then, in a sort of reverse auction, TNC asks farmers how much they would charge to temporarily flood their land to accommodate the birds, and pays farmers with the lowest bids to do so for a few weeks or months. The Nature Conservancy says the year-old program has been a success, enabling the organization to rent habitat for roughly 0.5 to 1.5 percent of what permanent protection costs. The program's budget is $1 million to $3 million annually. Forty farmers flooded roughly 10,000 acres last year, and sightings of key migratory bird species were 30 times above average, according to TNC.
10 Jun 2014:
Air Pollution Smartphone App
Seeks to Shame China's Polluting Factories
A new smartphone app
seeks to shine a spotlight on major Chinese polluters by letting users see in real-time which factories are violating air pollution emissions
App monitors factories' air pollution in China.
limits. The app, developed by the Beijing-based Institute of Public and Environmental Affairs (IPE), uses data from some 15,000 factories throughout China that are now required to report emissions to local officials and the Environment Ministry on an hourly basis. The government made all the data public at the beginning of this year, but now, for the first time, those data are available in one place through IPE's app and website. The app allows users to check air quality data for 190 cities and share air emissions data from polluters in those areas. Factories producing excessive emissions are shown in red. "If the air quality is bad you can switch (to the factory map) and see who is in your neighborhood," IPE's senior project manager explained.
09 Jun 2014:
Air Conditioning Can Raise
Urban Nighttime Temperature by 2 Degrees
Excess heat from air conditioners raises outdoor temperatures at night by nearly 2 degrees F (1 degree C), worsening the urban heat island effect and increasing cooling demands, according to research
from Arizona State University. Studying the Phoenix metropolitan area, researchers found that air conditioning systems pumped more waste heat into the air during the day, but the effect on near-surface temperatures was negligible. The same was not true for nighttime temperatures, however, when waste heat significantly boosts air temperatures because of nighttime atmospheric conditions. Air conditioning systems can consume more than 50 percent of total electricity
during extreme heat, the researchers note, and summertime extreme-heat days are projected to become more frequent and intense as a result of climate change. Redirecting waste heat from air conditioning systems to household appliances such as water heaters, for example, could help alleviate the problem, the scientists say. They project that such strategies would save at least 1,200 to 1,300 megawatt-hours of energy per day in the Phoenix metropolitan area alone.
Interview: The Small College That
Launched Fossil Fuel Divestment
When Stanford University announced in May that it would divest its endowment of coal mining companies, it was following the lead of a tiny college in rural Maine
that dubs itself “America’s environmental college.” A year and a half earlier, Stephen Mulkey, the president of Unity College
stood on a stage with Bill McKibben, the founder of 350.org and lead cheerleader for the divestment movement, to announce that his college would be the first institution of higher learning to rid its endowment of all fossil fuel holdings. In an interview with Yale Environment 360
, Mulkey, a climate scientist, talks about the ethical imperative behind the decision to divest, and his vision for, as he puts it, a re-engineering of the way the environmental sciences are taught.
06 Jun 2014:
Brazil Leads the World
In Cutting Deforestation, Analysis Finds
Brazil has become the world leader in reducing deforestation and, at the same time, has increased its soy and beef production, researchers report
Amazon rainforest near Manaus, Brazil
. The country has cut its forest loss by 70 percent since 2004, sparing more than 86,000 square kilometers of rainforests and keeping more than 3.2 billion tons of carbon dioxide out of the atmosphere. Brazil's decline in deforestation in 2013 alone represented a 1.5 percent reduction in global emissions that year, the report says; globally, tropical forest loss
accounts for 15 percent of global carbon dioxide emissions. The analysis credits the success to bold government policies, pressure from environmental groups, and market fluctuations in the price of soy and beef, but the authors warn that these wins may be short-lived without more positive incentives for farmers. “These gains are globally significant, but fragile,” one researcher explained. “We’re bumping up against the limits of what can be achieved through punitive measures.”
05 Jun 2014:
Coating for Roof Tiles Could
Help Clear Smog-Causing Air Pollutants
Engineering students have created a roof tile coating
that, when applied to an average-sized residential roof,
Coated tiles (left) and an uncoated tile (right).
breaks down the same amount of smog-causing nitrogen oxides per year as a car driven 11,000 miles makes. If applied to one million roofs, the titanium-dioxide based coating, which costs roughly $5 per roof, could clear 21 tons of nitrogen oxides each day, the team calculated. That could put a noticeable dent in atmospheric levels of the pollutant; in Southern California, for example, an average of 500 tons of nitrogen oxides are emitted daily. The team, which was recently recognized in a U.S. Environmental Protection Agency student design contest, showed that their tiles could remove 88 to 97 percent of nitrogen oxides in laboratory tests — a feat that other roof tile prototypes have not demonstrated.
04 Jun 2014:
New Ozone-Depleting Gases
Discovered in Atmosphere, Researchers Say
Researchers this week identified three new ozone-depleting gases
in the atmosphere, bringing the total number of such gases discovered this year to seven.
Ozone hole as of September 2013
Alone, none of the three gases were found in concentrations high enough to harm the ozone layer, researchers from the University of East Anglia. But the scientists believe more such gases will likely be discovered, and, cumulatively, they could have a significant impact. Two of the newly discovered gases are chlorofluorocarbons (CFCs) and one is a hydrochlorofluorocarbon (HCFC), both of which were once widely used in refrigerants. All three of the newly discovered gases are likely man-made, researchers said. Both CFCs and HCFCs fall under the Montreal Protocol
, an international agreement that bans the use of 13 such compounds. Including the four new gases discovered earlier this year, there are now a total of 20 known ozone-depleting gases.