Old Gas For New Climate

Trapped Gas Bubbles Ice sample with ancient gas bubbles. NSF

We all know the climate is changing. But just how complicated is that process and how many factors are involved in creating this planate-wide problem? To partly answer that question, scientists have gone back nearly 90,000 years to examine Antarctic ice core samples, or, more specifically, the gas they contain. Their findings demonstrate the complex interplay between different geological players that contribute to climate changes and trends. The report implies that global warming, carbon dioxide levels, and ocean currents are not individual influencers on climate change but rather intertwined with each other. Knowing how these factors interacted many millennia ago will hopefully help scientists better understand climate change today and possibly predict future trends.

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.

These gas measurements provide a snapshot of carbon dioxide levels and ocean currents between 20,000 and 90,000 years ago. CO2 levels now are far higher. Does this mean that we can soon look forward to sunbathing off the coast of Antarctica without fear of riptides? Probably not. While one future scenario is that global warming continues to lead to changes in ocean currents, which releases more CO2 into the atmosphere, which in turn creates an even warmer climate, the very fact that CO2 levels are so much higher now could change this interconnected relationship leading to as yet unknown results. Next up for Ahn and Brook is releasing more gas from a new ice core to create a higher resolution snap shot in hopes of learning more about the mutual influences of these factors and in so doing, provide more insight into our present and our future.