SCIENCE

Dalhousie University professor Boris Worm, one of the paper's co-authors, said that "existing marine protected areas are too small, too few and too far apart to prevent the tragedy of the oceans, which is arising due to the unbridled demand for seafood."

A number of factors have contributed to this trend of overexploitation, according to the study, including new export demands from the restaurant and aquarium trades, more sophisticated fishing technology, and rapid air transport of fish.

"What makes roving banditry different from most commons dilemmas is that a new dynamic has arisen in the globalized world: New markets can develop so rapidly that the speed of resource overexploitation often overwhelms the ability of local institutions to respond," said the paper's lead author, professor Fikret Berkes of Canada's University of Manitoba.

-- Juliet Eilperin

Rising Ocean Temperatures Linked to Stronger Hurricanes

The primary reason why hurricanes worldwide have become increasingly strong over the past 35 years is that ocean temperatures have been rising, creating conditions favorable to Category 4 and 5 storms.

Using statistical analysis and information theory to tease out the causes of hurricane strength in six ocean basins, researchers at the Georgia Institute of Technology concluded that only the surface water warming had a significant long-term effect. The results support two other studies published last year that found a similar correlation.

The rise in water temperatures in oceans worldwide is widely seen as a consequence of the buildup in greenhouse gases in the atmosphere -- the same phenomenon that is believed to be causing general global warming.

The new hurricane study, published in the journal Science, looked at a number of other factors that could cause hurricanes to become more intense -- including vertical wind shear (winds at ocean levels blowing in different directions or speeds than winds at higher altitudes), decreased humidity levels in the lower atmosphere, and large-scale air circulation patterns.

While all the factors were associated with some short-term variation in hurricane intensity and some lasting changes in North Atlantic wind-shear patterns were noted, only the increased surface temperatures had a long-term effect.

"With this new paper, we firm up the link between the increase in sea surface temperatures and hurricane intensity, which has been a key issue in the debate about whether global warming is causing an increase in hurricane intensity," author Judith Curry said.

-- Marc Kaufman