DENVER (CBS4) - It might be easy to agree that global climates are changing, but what's driving the change is a much more controversial topic of conversation.
Climate scientists are confident that human activity is a main driver, but how did they come to that conclusion?
Research at places like the National Ice Core Lab in Lakewood, Colorado, help provide answers.
Scientists there use ice cores drilled in Antarctica to reconstruct Earth's climate over the past 800,000 years.
Each ice core is two meters long and pulled from over 1,000 feet below the surface.
Each meter of an ice core represents about 15 years of history at the South Pole. The deeper the ice the older its age.
Ice cores are flown to Colorado in large mobile freezers and then studied at various labs.
Inside ice cores are tiny pockets of air that contain atmospheric gas. When that air is extracted it can be analyzed to learn more about our past climate.
Scientists can determine everything from which season the ice formed in to events that might have been happening globally, such as large volcanic eruptions.
Ice core data has revealed higher concentrations of carabon dioxide since the beginning of the Industrial Revolution.
Until then the global average for carbon dioxide had never reached higher than 280 parts-per-million.
But today values have exceeded 400 parts-per-million.
"We've never seen this in the last 800,000 years. We're talking in less than 100 years we've seen carbon dioxide levels climb faster than what it took thousands of years to achieve in the past," said Mindy Nicewonger of the University of California at Irvine.
The rapid increase in carbon dioxide is a concern for scientists because there's a strong relationship between carbon dioxide and temperatures that have been documented over time.
"With the rate at which carbon dioxide is increasing in our atmosphere, by the end of the century, it's going to be at levels where we don't really know what the potential impacts will be," said Nicewonger.
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