Despite a longstanding global decline in fertility rates, the world is still on a path to exceed 9 billion people by mid-century.

NASA called off the launch because of a hydrogen leak in a vent line between the main engines and the external fuel tank.

If there's broad agreement on the energy challenge, is the climate fight necessary?.

The space shuttle Discovery is set to lift off Wednesday on a two-week mission, carrying a replacement part for a water recycler and a final set of solar arrays for the International Space Station.

The Environmental Protection Agency proposed a rule that would require a broad range of industries to tally and report their greenhouse gas emissions.

The Energy Department made a $500 million math error a year ago when it withdrew its support from a “near-zero emissions” coal plant in Illinois.

There are a host of new methods that researchers are using to study animals in the wild without ever coming in contact with them.

Is the annual loss of an hour messing with your circadian rhythm?

Two new viral infections seem to have an effective treatment in an old antimalaria drug.

New research shows some evidence than rising acid levels in the ocean is affecting the ability of small marine organisms to create shells.

In a rare display of planning, one chimp hoards weapons to throw at future visitors.

What impact will President Obama’s move to lift the ban on stem cell research have on current work?

“Quants” try to use physics to untangle the messiest of human activities — making money.

In recent years, more and more studies have found effective uses for hyperbaric oxygen therapy.

Once cancer has invaded and set the new pace for your life, you’d be hard pressed to try and change it.

Tests to find the source of “mystery tumors” may help doctors treat them more effectively.

Researchers have discovered that general networks of the brain are responsible for religious beliefs.

Dr. Beers’s seminal research found that some widely used prescription drugs led to harmful and unnecessary side effects in the elderly.

Emergency room visits for headaches increase as the weather gets warmer.

To the Editor:.