A central tenet of demography is that global population will peak at 9 to 10 billion this century and then gradually decline as poorer countries develop. But that assumption may be overly optimistic — and if it is, population will continue to rise, placing enormous strains on the environment.

In Germany’s capital — and in cities as diverse as Hong Kong and Chicago — raising bees on rooftops and in small gardens has become increasingly popular, as urban beekeepers find they can reconnect with nature and maybe even make a profit.

In pockets ranging from mountain peaks to bogs, scientists are discovering plants and animals that survived previous eras of climate change. Now, conservation biologists say, these climate “relicts” could shed light on how some species may hang on in the coming centuries.

Even as the impacts of climate change intensify, many Americans remain confused by the issue. In an interview Yale Environment 360, climate scientist Katharine Hayhoe discusses what rising temperatures will mean for the U.S., how to talk with climate skeptics, and what she would say to Texas Gov. Rick Perry to prod him into action on global warming.

Airborne microbes can travel thousands of miles and high into the stratosphere. Now scientists are beginning to understand the possible role of these microbes — such as bacteria, fungal spores, and tiny algae — in creating clouds, causing rain, spreading disease, and even changing climate.

There are striking similarities between the current economic and ecological crises — both involve indulgent over-consumption and a failure to consider the impacts on future generations. But it’s not too late to look to new economic and environmental models and to dramatically change course.

Daunted by high up-front costs, U.S. homeowners continue to shy away from residential solar power systems, even as utility-scale solar projects are taking off. But with do-it-yourself kits and other innovative installation approaches now on the market, residential solar is having modest growth.

From understanding the cumulative impacts of widely used chemicals to preparing for life in a warming world, a host of environmental health issues now face medical experts. In an interview with Yale Environment 360, Lynn Goldman, dean of the George Washington University School of Public Health and Health Services, talks about meeting the challenges.

In the wake of the Fukushima meltdowns, some nations are looking to move away from nuclear power. But not China, which is proceeding with plans to build 36 reactors over the next decade. Now some experts are questioning whether China can safely operate a host of nuclear plants.

The contentious practice of hydrofracking to extract underground natural gas has now made its way to South Africa’s Karoo, a semi-desert known for its stark beauty and indigenous plants. But opposition is growing amid concern that fracking will deplete and pollute the area’s scarce water supplies.

Some skeptics have suggested the real culprit behind rising temperatures is increased solar activity. But a wide variety of data and experiments still provide no solid evidence to refute the scientific consensus that greenhouse gas emissions are the major reason the planet is heating up.

When Barack Obama won the presidency in 2008, environmentalists were optimistic that their issues would finally become a priority at the White House. So how is Obama doing? Yale Environment 360 asked a group of environmentalists and energy experts for their verdicts on the president's performance.

With global population expected to surpass 7 billion people this year, the staggering impact on an overtaxed planet is becoming more and more evident. A two-pronged response is imperative: empower women to make their own decisions on childbearing and rein in our excessive consumption of resources.

A rapidly expanding universe of citizens’ groups, researchers, and environmental organizations are making use of social media and smart phone applications to document changes in the natural world and to mobilize support for taking action.

Phosphate has been essential to feeding the world since the Green Revolution, but its excessive use as a fertilizer has led to widespread pollution and eutrophication. Now, many of the world’s remaining reserves are starting to be depleted.

Exploiting North America’s largest oil deposit has destroyed vast stretches of Canada's boreal forest, arousing the ire of those opposed to this massive development of fossil fuels. Now those opponents are battling the Keystone XL pipeline, which would pass through environmentally sensitive Western lands as it moves the oil to market.

Even before this spring’s ominous clampdown on China’s public-interest lawyers, writers, and activists, the country’s fledgling environmental community felt the authorities’ noose tightening.

For eons, the polar marine food chain has been closely linked to the seasonal formation and retreat of sea ice. Now, as that ice rapidly melts in the Arctic and along the Antarctic Peninsula, this intricate web of life is undergoing major shifts, benefiting some creatures and putting others at risk.

Few places in the U.S. are as well suited to developing renewable energy as the contaminated sites known as “brownfields.” But as communities from Philadelphia to California are discovering, government support is critical to enable solar and wind entrepreneurs to make use of these abandoned lands.

With ever-greater quantities of seafood coming from aquaculture operations, some companies are working on ways to reduce the environmental impact of fish farming. In an interview with Yale Environment 360, Josh Goldman of Australis Aquaculture talks about his highly praised closed-containment fish farm in Massachusetts.