Fragile Earth. Published by HarperCollins. iTunes, $3.95.
Reviewed by Carl Zimmer
Infinity can be cruel. Tablet computers have become so powerful that it's practically impossible to reach the limits of what you can do while creating an ebook. You can embed videos, sprinkle music and voices here and there, let people post a book-inspired thought to Twitter, manipulate a simulated bat, incorporate an encyclopedia of information about chemistry, and on and on. Unfortunately, this virtual infinity of possibilities may leave ebook creators with a virtual infinity of work. Some science ebooks we've reviewed rise to that challenge. They sport a well-integrated collection of features. Other ebooks seem like wild acts of desperation. And others still are acts of wise self-restraint. Yes, you could make a science ebook that does many things poorly. Or you could make a science ebook that does one thing well. One such ebook is Fragile Earth.
Fragile Earth got its start in 2006 as a beautifully disturbing coffee table book published by Collins, filled with satellite images showing how humanity is reworking the planet. "Before" and "after" photographed were paired to show how deforestation, climate change, and other factors have changed the face of Earth. Now Collins has turned it into an app. The Youtube video below gives you a good run-through of its features. The most important one is that instead of putting images side by side, the app does what a book cannot: it lays them on top of each other. You can then use a screen button to slide one picture away to reveal the other one underneath. I'm not quite sure of the visual neuroscience behind this effect, but it works very well. Seeing the same landscape in Alaska covered by glaciers a few decades ago now turned to mostly bare Earth is a sobering experience.
Fragile Earth is not perfect, though. The book and the app alike are presented as a way to see how we're changing the planet. But the app is loaded with other images that show natural changes, such as the devastation caused by the eruption of Mount Saint Helens. Combining these images together makes no thematic sense; the only thing that joins them together is an elegant slider. There's no introduction where you might find an explanation for what a volcano and the deforested Amazon have in common. Instead, Fragile Earth has short caption that describe the specifics of each set of images but leave you wanting more.
That's too bad, because Fragile Earth illustrates on a profoundly important fact about our species. In 2005, Bruce Wilkinson, a University of Michigan geologist, published a paper called, "Humans as geologic agents: A deep-time perspective." [free pdf] "Humans are now an order of magnitude more important at moving sediment than the sum of all other natural processes operating on the surface of the planet," Wilkinson concluded. We're also having other huge effects on the planet--acidifying the oceans faster than at any time in the last 300 million years, for example. Humanity isn't just leaving a mark on the Earth you can see from space. It's a mark that will be preserved in the fossil record for millions of years to come.
Before and after pictures can go a long way to showing the magnitude of that change. But without context, they can also oversimplify it. If you were to select a before and after pair of pictures of glaciers in the Himalayas, for example, you would not see a frightening retreat over the past decade. In fact, you might not see any change at all. Such specific cases are ripe for cherry-picking by global warming denialists. The reason that this one case does not refute global warming because of the overwhelming evidence of changes caused by global warming on a planetary scale--such as the overall loss of ice from the entire Arctic Ocean.
Fragile Earth would thus be a better app if its pictures had more context and a more coherent point. But I'm also glad that its creators didn't try to grasp for infinity.
Carl Zimmer writes frequently about science for the New York Times and is the author of 13 books, including A Planet of Viruses