John Nelson, writing about the creation of these images:

Having spent much of my life living near the center of that mitten-shaped peninsula in North America, I have had a consistent seasonal metronome through which I track the years of my life. When I stitch together what can be an impersonal snapshot of an entire planet, all of the sudden I see a thing with a heartbeat. I can track one location throughout a year to compare the annual push and pull of snow and plant life there, while in my periphery I see the oscillating wave of life advancing and retreating, advancing and retreating. And I’m reassured by it.

Of course there are the global characteristics of climate and the nature of land to heat and cool more rapidly than water. The effects of warm currents feeding a surprisingly mild climate in the British Isles. The snowy head start of winter in high elevations like the Himalayas, Rockies, and Caucuses, that spread downward to join the later snowiness of lower elevations. The continental wave of growing grasses in African plains.

But, overall, to me it looks like breathing.