Slices of ice cores drilled from the Earth’s depths in Antarctica and Greenland reveal details of our planet’s climate history.
Ice cores are cylinders of ice drilled out of an ice sheet or glacier sometimes to the depths of more than two miles deep, especially in Antarctica.
The oldest continuous ice core records date back some 800,000 years in Antarctica and more than 125,000 years in Greenland. These core samples contain vital information about past temperatures, precipitation patterns and various aspects of the environment throughout the ages, including carbon dioxide levels.
Each ice core sample encloses small bubbles of air that contain precise details of the atmosphere at a given period in history. From these air bubbles, it is possible to directly measure the precise concentrations of gases like carbon dioxide and methane in past millennias.
The ice core samples in both Greenland and Antarctica show us the concentrations of both carbon dioxide and methane have varied greatly at times in the past 400,000 years, based on the chart (from www.daviesand.com).
From the air bubbles in our oldest Antarctic ice core samples, we easily can see that changes in carbon dioxide (CO2) levels mirrored the prevailing climate of the time. There were low concentrations of the carbon dioxide during the cold periods and much higher levels during the warmer times as in recent years. In fact, the chart does show that we’re experiencing the highest concentration of carbon dioxide today than during the last 400,000 years.
The natural climate changes of the past 800,000 years were relatively gradual in most cases, but many abrupt changes were likely seen, particularly during the sudden onset of major ice ages. According to an article in Scientific American published in May 2013, plankton in oceans may absorb more of the carbon dioxide than once previously thought. And, it’s also been discovered that types of igneous rock, or volcanic rock, will also absorb carbon dioxide, but over a longer period of time.
Over time, major and minor ice ages have often followed periods of abnormal warming. There is speculation that the plankton and other carbon dioxide absorbing lifeforms or substances go into ‘overdrive’ to decrease those levels, resulting in the cooler periods. Perhaps our friend, Robert Felix, may be right after all in his prediction of an overdue, imminent major ice age arriving in the near future. Again, only time will tell.