What is the volume of the world's oceans? 1.332 billion cubic kilometers, according to scientists at the Woods Hole Oceanographic Institution.

The researchers report that the world's total ocean volume is less than the most recent estimates by a volume equivalent to about five times the Gulf of Mexico, or about 0.3% lower than the estimates of 30 years ago.

The results reveal how accurate scientists were in the past, using cruder techniques to measure ocean depth. As long ago as 1888, for example, John Murray dangled lead weights from a rope off a ship to calculate an ocean volume—the product of ocean area and mean ocean depth—just 1.2% greater than the new figure reported in Oceanography.

Using NASA satellite data and Google Earth, a Purdue University researcher has found evidence that North Korea is logging in the Mount Paekdu Biosphere Reserve, a 326,000-acre forest designated by the United Nations as a protected forest preserve. Mount Paekdu - together with an adjacent biosphere in China - has the world's highest plant biodiversity in a cool, temperate zone and is the habitat for many wildlife species, including the endangered Siberian tiger.

Since many researchers are unable to visit North Korea, the research was conducted using remote sensing data. Results were published in Biological Conservation.

Newborns learn during sleep, say the authors of a new study in the Proceedings in The National Academy of Sciences. The findings reveal valuable information about how newborns are able to learn so quickly from their environment, researchers say.

The study could also lead to identifying those at risk for developmental disorders such as autism and dyslexia.

"We found a basic form of learning in sleeping newborns, a type of learning that may not be seen in sleeping adults," said Dana Byrd, a research affiliate in psychology at the University of Florida.

Why do we get intense desires to eat certain foods? A pair of psychologists from Flinders University, Australia, say they may know. The team authored a review of the literature on food cravings and found that mental imagery may be a key component of food cravings — when people crave a specific food, they have vivid images of that food. The review was published in Current Directions in Psychological Science.

A mass extinction of fish 360 million years ago hit the reset button on life, setting the stage for modern vertebrate biodiversity, say researchers writing in PNAS. The mass extinction scrambled the species pool near the time at which the first vertebrates crawled from water towards land. Those few species that survived the bottleneck were the evolutionary starting point for all vertebrates--including humans--that exist today.

"Everything was hit; the extinction was global," said Lauren Sallan of the University of Chicago and lead author of the paper. "It reset vertebrate diversity in every single environment, both freshwater and marine, and created a completely different world."

Eighteen year-old James Popper, from Marlborough College, Wiltshire, has scooped major prizes at the Intel International Science and Engineering Fair, in San Jose, California from 9-14 May.