Fine particle pollution in Denver exceeded federal health standards on March 6, 2019, triggering a citywide alert.
AP Photo/David Zalubowski
Are health risks from air pollution less serious than we think? Mainstream scientists call this a fringe view, but it's getting high-level attention at the Environmental Protection Agency.
Recent extreme rains and weather in the Midwest are causing a multitude of problems in the topsoil that much of the nation's food supply relies on.
A collection of millions of bird sightings has identified the best places to invest in conservation.
A scholar who travels regularly to the US-Mexico border finds ecological links and a community on the other side that welcomes American visitors.
What creates such dramatic storms across the US Great Plains? The key factors are topography and temperature differences.
Can presidents undo decisions by their predecessors to protect federal lands from development? A recent court ruling on offshore drilling says no, and could also affect contested lands in Utah.
Globalization is making it harder to identify and trace outbreaks of foodborne illness. Technology can help, but consumers may also have to rethink their food choices.
Climate change science was driven by curiosity in the past. Now climate researchers need to focus on managing the risk of global warming's ill effects.
Starting in 2021, drivers will pay a fee to enter midtown and lower Manhattan during busy times of day. Will this clear New York's air and streets?
Rail advocates often make the case that trains are a cleaner mode of transportation, but why is that so? And what would it take to expand rail in the U.S.?
States are folding the social and economic costs of burning fossil fuels into their electricity policies, giving utilities a financial incentive to reduce greenhouse emissions.
A climatologist who studies precipitation trends explains how climate change is projected to make flooding events in the Midwest more severe and more frequent.
The FDA has given the green light to sell the first genetically engineered animal – farmed salmon –in the US.
What is proof? In both law and science, it's basically a consensus of experts – but they work at very different speeds. That means juries may reach verdicts on an issue before the science is settled.
Unless it sparks joy, go ahead and scratch this task off your spring-cleaning checklist.
Many nations are restoring degraded tropical forests to slow climate change, protect endangered species and improve rural life. But those forests often are cleared again soon afterward.
The 'used water' that flows from our showers, dishwashers and toilets isn't a waste to engineers – it contains valuable materials. The challenge is recovering them and turning them into products.
Even before the British billionaire invested US$1 billion in making the region 'climate-smart,' Jamaica, Barbados and Dominica were pioneering a renewable energy boom in the Caribbean.
In 2004 an underwater avalanche destroyed an oil platform off Louisiana, causing a 14-year spill. An expert on oil and gas seeps in the Gulf of Mexico warns that this could happen in other places.
What raises a common winter storm to the level of 'bomb cyclone'? It's all about rapid, sharp changes in atmospheric pressure – and the scientists who coined the term meant to highlight their power.
Adding industrial chemicals and natural alkaline minerals could slow climate change, but like other geoengineering proposals, it comes with many complex technical and legal challenges.
China, which once processed much of the world's scrap, has slashed imports of "foreign garbage." What can the US do to step up recycling at home?
Many people associate Henry David Thoreau with solitude in the outdoors. But Thoreau understood in the mid-1800s that there was no such thing as nature separate from humans.
Since 2008, Landsat data has been free for the world to use, spurring new applications and scientific research. But that door could soon slam shut.
These youngsters have ample fervor, and they are dramatically photogenic. Dismissing them as being fake or lightweight can spell trouble for members of the establishment.
EPA is moving to regulate two chemicals from a group called PFAS that are contaminating drinking water. A public health expert explains why the agency should take much broader action.
Washington, California and Florida are mulling a permanent switch to DST. Proponents say that doing so could improve health, save energy and prevent crime.
Why do scientists spend so much time and money mapping the DNA of species like white sharks? Single studies may offer insights, but the real payoff comes in comparing many species to each other.
Natural gas supplies are growing, but so are other markets for it besides power generation.
Chemical pollution and hunting pushed Ospreys to the edge of extinction in the mid-20th century. Today, they have rebounded and can be spotted worldwide, often nesting on manmade structures.
Energy storage could prove an inexpensive way for power companies to handle heat waves and other times when consumers use more electricity than usual.
Climate justice policies could potentially double as tools of colonialism that harm people outside the US.
US cities were designed and engineered around cars. Now some are working to increase walking and biking, but the shift isn't easy.
There are precedents regarding power generation and ethanol but no nation has ever achieved as comprehensive and dramatic this fast.
It will be hard and complicated to replace Venezuela's heavy sour crude.
An Obama administration veteran offers some insights from his experience about driving massive increases in clean energy.
It's often more effective, cheaper and less controversial than other efforts to confront climate change.
Urban farming can make it easier for city residents to obtain healthy, affordable food. But to raise big yields from small pieces of land, farmers need training and support.
US agriculture is dominated by large farms that rely on chemical inputs. In contrast, regenerative farming makes land and water healthier by mimicking nature instead of trying to control it.
Whether to attending a conferences or giving in to a meeting, the global research community is keen on air travel. That’s a habit that needs to change.
Can a new government, perhaps by shoring up democracy and oversight, harness this commodity for peace and prosperity?
Dozens of cities, states and nations are enacting bans and restrictions on single-use plastic bags and other items. A legal expert explains how a global treaty could build on these efforts.
The coal, oil and natural gas industries are also connected with human rights violations, public health disasters and environmental devastation.
Polls suggest that the majority of Americans think climate change is real, is caused by humans and needs to be addressed. But climate change isn't a priority when Americans go to vote.
The Trump administration wants to end federal protection under the Clean Water Act for many small streams and wetlands. But as a geoscientist explains, these are critical parts of large river systems.
Marshes, swamps and other kinds of wetlands provide valuable services, such as effective natural flood control. But they are being destroyed for development in many parts of the world.
An atmospheric scientist explains why water can do some strange-looking things at very cold temperatures, and what's different about snowfalls on Mars.
These technologies could turn into a powerful tool for fighting global warming, and they have the potential to address historical climate injustices.
Making electric grids better able to withstand extreme weather events will require teamwork from engineers, researchers and the government.
Life-threatening cold temperatures in the central US are caused by changes in wind circulation in the Arctic that bring cold air south. Climate change could make these events more frequent.
Nearly 1,800 Brazilian dams are at risk of failure, according to the government. Fixing them is expensive – but ignoring aging dams can have considerable social, economic and environmental costs.
Fifty years after a major oil spill in Santa Barbara helped launch the environmental movement, Californians strongly oppose the Trump administration's push to expand offshore drilling.
It's cheaper to prevent biological invasions than to react after they happen. But it's hard to detect invaders while there are still just a few of them. Knowing when and where to look can help.
Climate change is happening and will intensify in coming decades. Some experts say it's time for a triage strategy that focuses investments where they are most likely to have an impact.
Snorkeling off the California coast, a high school student found heaps of golf balls on the ocean floor. With a marine scientist, she showed that golf courses were producing tons of plastic pollution.
What is the best way to conserve US national parks in a climate-altered future? One answer is connecting parks and other public lands, so plants and animals can shift their ranges.
Distrusting large federal bureaucracies isn't reserved for conservatives anymore.
There are ways to reduce the risk of protests like France's yellow vests movement.
Fixes for small pieces of massive problems show that overarching crises may be less hopeless than they appear.
Research into volcanic activity in the waters off Indonesia shows how active this region is and how destructive landslide-caused tsunamis can be.
Researchers unpack the vast impact of plastic on our society – from emerging health worries and pollution to recycling and plastic's contributions to modern convenience.