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Pfeffer and his colleague, Shad O'Neel, are taking its vital signs, measuring the speed of the glacier over several years to determine whether it's speeding up or slowing down.
To do this, they fire a laser survey gun at reflective targets that they must deploy on the surface of the ice.
It is rapidly-calving glaciers, like these, that are the main contributors to rising sea levels.
Alaska's Columbia is one of the biggest ocean-feeding glaciers in North America.
As the pilot hovers a few inches above the glacier, O'Neel positions the target onto the ice.
Pfeffer locks onto the target and shoots a laser that reflects back to the stationary gun, recording the position. By tracking its movement with the laser, over several days, they will be able to calculate the speed of the Columbia.
Since the Industrial Revolution, our burning of fossil fuels has ratcheted up the output of greenhouse gases like carbon dioxide, which trap heat in the atmosphere.The waxing and waning of the ice sheets have been implicated in who lives where and what they do.And there are even some people who have suggested that we're humans now, in part, because we were responding to the changes in our environment that were linked to the growth and shrinkage of the ice.(Program not available for streaming.) Follow photojournalist James Balog to some of the most remote and beautiful places on Earth as he documents the disappearance of an icy landscape that took thousands of years to form.An artist, scientist, explorer, and former mountain guide, Balog braves treacherous terrain to site his cameras in ideal locations to record the unfolding drama.
His passion is to document it and help scientists understand these monumental changes.