Scientists: Pacific Ocean heating up faster than in past 10,000 years

The Pacific Ocean is warming at a faster rate than it has in the previous 10,000 years, suggesting more difficulties in countering the effects of global warming, according to a new study published Friday in the journal Science.

The study, "Pacific Ocean Heat Content During the Past 10,000 Years," reconstructs Pacific Ocean temperatures in the last 100 centuries by measuring the chemistry of ancient marine life to recreate the climates in which they lived.

In 2003, researchers went to Indonesia to collect cores of sediment from the seas where water from the Pacific flows into the Indian Ocean. They compared the levels of magnesium to calcium in the shells of Hyalinea balthica, a one-celled organism buried in those sediments, in order to estimate the temperature of the middle-depth waters where the organism lived, about 1,500 to 3,000 feet below sea level.

The measurements of middle-depth temperatures in this region are representative of the larger western Pacific, the researchers said, since the waters around Indonesia originate from the mid-depths of the North and South Pacific.

Based on these findings, researchers concluded that the middle depths have warmed 15 times faster in the last 60 years than they did during natural warming cycles in the previous 10,000 years. 

Pacific intermediate depths have generally cooled during the past 10 millennia, but sometime around the year 1600, temperatures began gradually rising. Over the last 60 years, water column temperatures, measured from the surface to 2,200 feet, increased .32 F.

Some experts, though, find aspects of the study problematic. For instance, John Abraham, a professor of thermal sciences at the University of St. Thomas School of Engineering, Minnesota, said that sediment studies are poor measurements of recent temperature information. Uncertainties in the rates at which sediments form coupled with bioturbation – a process through which sedimentary layers are mixed by animals – result in a great deal of doubt.

Despite skepticism, experts believe studies like this show that Earth is experiencing an unprecedented energy imbalance.

Current research indicates that heat stored in the oceans could be released into the atmosphere in the future, obstructing human efforts to stabilize global temperatures by cutting greenhouse gas emissions. Scientists warn that global warming, caused by the emissions, could dramatically raise average temperatures by the end of the century, causing widespread famine and violent storms.

Scientists have also warned that ocean warming could adversely affect marine life and accelerate climate change. Previous studies have shown rising ocean temperatures to be both a symptom and a multiplier of global warming.

Future studies, writes Abraham, can build on this one and produce a more comprehensive picture to gain a better understanding of what the future climate will be if humans do not curtail greenhouse emissions.

Al Jazeera