Marijuana causes hallucinations and paranoid delusions in some, doctors say.

It can suck carbon dioxide, a major greenhouse gas, right out of the air.

Researcher says ladders should be treated with same respect as power saws.

Doctors propose new ways to evaluate life-or-death situations.

Study is the first to find disease outbreaks directly linked to rising temperatures.

Sole survivor of tortoise species may not be alone for long.