Polar bears are likely to lose out to grizzly bears in fierce competition for food as climate change drives the two species closer together into shared habitat, biologists concluded in a study released on Tuesday.

The research was based on 3-D computer modeling that compared the skull and jaw strength of the two bruins and found polar bears ill-suited to the tougher chewing demands posed by the

The Arctic's sea ice pack thawed to its third-lowest summer level on record, up slightly from the seasonal melt of the past two years but continuing an overall decline symptomatic of climate change, U.S. scientists said on Thursday.

The Arctic ice pack melted this summer to its third-smallest size on record, up slightly from the low points of the past two years but continuing an overall shrinking trend symptomatic of climate change, U.S. scientists said on Thursday.

Scientists have detected mercury contamination in every one of hundreds of fish sampled from 291 freshwater streams, according to a U.S. government study released on Wednesday.

Marine scientists from California are venturing this week to the middle of the North Pacific for a study of plastic debris accumulating across hundreds of miles (km) of open sea dubbed the "Great Pacific Garbage Patch."

The biggest seawater desalination plant in the Western Hemisphere, north of San Diego, can begin construction by year's end after a six-year effort to win regulators' approval, the developer said on Thursday.

California on Wednesday is expected to adopt landmark rules to curb carbon emissions from transportation fuels despite intense opposition from some who say the proposal is biased against corn-based ethanol.

Arctic sea ice, a key component of Earth's natural thermostat, has thinned sharply in recent years with the northern polar ice cap shrinking steadily in surface area, government scientists said on Monday.