20 images that show how much we've reshaped planet Earth in the past 70 years

April 22 is Earth Day, a world holiday celebrating our planet — the only home we've got (so far).

Humans have had an unmistakable impact on Earth — one that pops out in sharp relief when you look at this collection of images comparing what specific areas look like now to how they appeared in the past.

In some cases, the images (mostly from NASA, unless otherwise noted) were taken as far as 50 years apart; in other cases, they were snapped with just 10-15 years in between.

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Photographs from the 1940s to the 2000s show the drastic impact of climate change on our planet's glaciers. Here is a photo of Alaska's Muir Glacier, pictured in August 1941 (left) and August 2004 (right).

Here's the snow that remained on Matterhorn Mountain in Switzerland in August 1960 (left), compared with August 2005 (right).

Starting in the 1970s, NASA began using satellite images to document deforestation in several national parks around the world. Here's Mount Elgon National Park in Uganda in 1973 (left), compared with the park in 2005 (right).