Time lapse photography of shrinking glaciers makes a powerful visual case for the impact of human-caused global warming. That’s why, for example, it’s used in former Vice President Al Gore’s slideshow, An Inconvenient Truth, and by GlacierWorks, a nonprofit started by famed mountaineer and filmmaker David Breashears to document climate change in the Himalaya.
But is human activity really causing the world’s glaciers to melt? After all, these rivers of ice have been melting ever since the Little Ice Age came to an end nearly two centuries ago, long before humans pumped out enough greenhouse gases to change the global climate. Perhaps the glaciers would be retreating even if humans never once burned a fossil fuel or cleared a forest.
“It seems to be so obvious that when it is getting warmer — and it is getting warmer because of human activity — the glaciers are melting because of human activity, but that actually hasn’t been shown before,” Ben Marzeion, a climate scientist at the University of Innsbruck in Austria, told NBC News.
Now it has.