Urban stormwater runoff is a serious problem, overloading sewage treatment plants and polluting waterways. Now, various U.S. cities are creating innovative green infrastructure — such as rain gardens and roadside plantings — that mimics the way nature collects and cleanses water.

Martha Schwartz, a professor at Harvard’s Graduate School of Design, explains in a Yale Environment 360 interview how creative landscape architecture can help cities become models of sustainability in a world facing daunting environmental challenges.

The Andes in eastern Peru, with steep slopes and remarkable biodiversity, are what one scientist calls a “perfect laboratory” for studying the effects of climate change. E360 contributor Elizabeth Kolbert trekked there with researchers seeking to determine if tree populations can move uphill fast enough to survive warming temperatures.

Much attention has been paid to how global warming is affecting the world’s polar regions and glaciers. But a leading authority on tropical forests warns that rising temperatures could have an equally profound impact on rainforests and are already taking a toll on some tropical species.

One of the thorniest questions facing climate scientists is whether human-induced climate change is leading to more heat waves, floods, and extreme weather events. Now, employing increasingly sophisticated methods of studying weather extremes, climatologists say they are closer to answering that key question.

The Japanese earthquake and tsunami remind us that we exist in geologic time and in a world where catastrophic events beyond our predicting may occur. These events — and the growing specter of climate change — show how precariously we exist on the surface of a volatile planet.

For decades, deadly outbreaks of cholera were attributed to the spread of disease through poor sanitation. But recent research demonstrates how closely cholera is tied to environmental and hydrological factors and to weather patterns — all of which may lead to more frequent cholera outbreaks as the world warms.

Grizzly bears mating with polar bears. Red foxes out-competing Arctic foxes. Exotic diseases making their way into once-isolated polar realms. These are just some of the worrisome phenomena now occurring as Arctic temperatures soar and the Arctic Ocean, a once-impermeable barrier, melts.

Among the many measures the world can take to wean itself off fossil fuels, few match the benefits of making homes, business, and cars more energy-efficient. But financial and psychological barriers have kept individuals, businesses, and governments from realizing efficiency’s great potential.

Doug Peacock has been tireless defender of the Yellowstone grizzly for decades, but he believes the bear may now be facing its toughest threat yet. In an interview with Yale Environment 360, Peacock talks about the insect infestation that is destroying a key food source for grizzlies and recalls some of his closest encounters with the bears.

Forecasting what the Earth’s climate might look like a century from now has long presented a huge challenge to climate scientists. But better understanding of the climate system, improved observations of the current climate, and rapidly improving computing power are slowly leading to more reliable methods.

The world’s oceans have been experiencing enormous blooms of jellyfish, apparently caused by overfishing, declining water quality, and rising sea temperatures. Now, scientists are trying to determine if these outbreaks could represent a “new normal” in which jellyfish increasingly supplant fish.

Researchers disagree about what the economic costs of climate change will be over the coming decades. But the answer to that question is fundamental in deciding how urgent it is to take action to reduce emissions.

To offset their own carbon emissions, European companies have been overpaying China to incinerate a powerful greenhouse gas known as hfc 23. And in a bizarre twist, those payments have spurred the manufacture of a harmful refrigerant that is being smuggled into the U.S. and used illegally.

The idea of creating biochar by burning organic waste in oxygen-free chambers — and then burying it — is being touted as a way to cool the planet. But while it already is being produced on a small scale, biochar’s proponents and detractors are sharply divided over whether it can help slow global warming.

The fringes of the coldest continent are starting to feel the heat, with the northern Antarctic Peninsula warming faster than virtually any place on Earth. These rapidly rising temperatures represent the first breach in the enormous frozen dome that holds 90 percent of the world’s ice.

Britain’s new government is proposing radically new energy policies, with a “Green Deal” that would retrofit the country’s woefully energy-inefficient housing stock. In an interview with Yale Environment 360, UK Energy and Climate Minister Greg Barker talks about why an overhaul of the approach to energy is essential for the nation’s future.

Amid China’s seemingly boundless emissions of industrial pollutants, there are signs of hope. Discharges of sulfur dioxide, which causes acid rain, have actually decreased, offering some evidence that China is starting to establish a culture of pollution monitoring and control.

By year’s end, regulators are expected to approve a host of solar energy projects in California that could eventually produce as much electricity as several nuclear plants. In an interview with Yale Environment 360, John Woolard, the CEO of the company that has begun construction on the world’s largest solar-thermal project, discusses the promise — and challenges — of this green energy boom.