Jinho Ahn and Edward Brook of Oregon State University executed the study with support form the National Science Foundation and their report was published in the journal Science. The team essentially crushed the frozen bubbles encased in their 390 ice core samples—carefully, of course, some were almost 90,000 years old—to release some truly old gas. Researchers then measured the carbon dioxide levels in each sample and compared the numbers with climate data from the icy north (Antarctica and Greenland), and with ocean sediments from the south (Chile and the Iberian Peninsula). With all of these pieces of data at hand, they knew the CO2 levels, the temperature, and how fast or slow the ocean currents were moving in both the North Atlantic and the Southern Ocean. What they found can be boiled down to this: Increased CO2 levels equaled a hotter Earth and reduced circulation of ocean currents in the North Atlantic. In the Southern Ocean as well, it appeared that CO2 levels increased while ocean currents weakened.