Ocean warming over the last two decades has disrupted the breeding of the tufted puffin, a seabird native to the North Pacific. According to a study published online this week by the Proceedings of the National Academy of Sciences, the years characterized by the warmest sea-surface temperatures (which are associated with global climate changes) exhibited significantly decreased growth rates for the birds and low fledging survival. The findings indicate that future global warming could render the puffin's largest breeding ground unsuitable.

Carina Gjerdrum of Simon Fraser University and her colleagues studied a puffin breeding ground located on Triangle Island off the coast of British Columbia. The scientists collected 16 years of breeding season data and compared it to information on sea-surface temperatures over the same time period. Between 1975 and 2002, the average temperature near Triangle Island increased by 0.9 degree Celsius, which is consistent with global climate trends. The researchers found that during that time the puffins' reproductive success was greatest in years with intermediate temperatures between 8.9 and 9.9 degrees Celsius. In breeding seasons with temperatures higher than 9.9 degrees C, however, hardly any young survived the season.

The birds seem to have adapted somewhat to warming temperatures by hatching sooner. Between 1994 and 2002, hatch dates were 16 days earlier than those of the 1970s or 1980s. The authors conclude that "future changes in ocean climate will likely be the major factor determining the viability of existing populations of tufted puffins and perhaps many other marine species."