Christian Åslund is a Swedish photojournalist. He has collaborated with Greenpeace for nearly twenty years and recently published a number of fantastic Now&Then images showing climate change in the Arctic.
When National Georgraphic asked him about his most remarkable assignment so far he replied: "It's got to be the glacier comparison that we did [at Svalbard] because it's interesting on so many levels—our access to the archives there from the early 1900s, and then being able to trace where the photographers were, because we didn't know exactly where they shot from. We had to track down where the photos were taken, and then go on location and then sort of follow their footsteps."
Excellent idea !