Ocean's average temperature is 3.5 degree Celsius

"The reason this study is so exciting is that previous methods of reconstructing ocean heat content have very large age uncertainties, (which) smooths out the more subtle features of the record," said co-author Sarah Shackleton from Scripps Institution of Oceanography at the University of California San Diego. "Our precision is about 0.2 degree Celsius now, and the warming of the past 50 years is only about 0.1 degree Celsius," said Jeff Severinghaus, geoscientist at Scripps Oceanography.

Severinghaus said advanced equipment can provide more precise measurements, allowing scientists to use this technique to track the current warming trend in the world's oceans. Determining changes in the average temperature of the entire world's ocean has proven to be a nearly impossible task due to the distribution of different water masses.