Earth : Evolution of a Habitable World (Cambridge Atmospheric & Space Science Series)

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Summary: The evolution of our planet from a new perspective
Review: Earth, Evolution of a Habitable World by Jonathan I. Lunine

Review by Philip Eklund

Dr. Lunine is a Professor of Planetary Sciences at the University of Arizona, and a NASA advisor. His new book describes Earth's evolution in a fresh perspective, in relation to its sister planets, particularly Mars and Venus. This 319 page textbook covers Earth's origin, the development of its atmosphere and oceans, the variations of its orbit and climate, and at what point we are enmeshed in its long and lively history. The reader can see how we can be unwittingly in the teeth of an ice age and why the number of species has crescendoed now, in our time.

The vast territory that Lunine succinctly covers is all that anyone with a bit of gumption needs to become an authority on the state of our planet. Guideposts to this territory include the sciences of measurement (basically, math, the metric system, and dating methods), and of physics as applied to geology and biology (and some chemistry). Unfortunately Lunine sometimes lapses into off-topic diversions of astronomy (Doppler shifts, lunar phases, Stonehenge, eclipses, and aging planets by the density of their craters). Also, there is no glossary, but the index is adequate. (A few undefined jargons, like "cratonization", sneak in.)

The book is profusely illustrated by Jonathan's wife, Cynthia. There is a color section, mostly of refugees of some astronomy book showing various wonders of the universe. But one color map of the Southwest occupied my attention for a long time. It compares vegetation regimes during the Pleistocene and the Present, the ancient record being derived from pollen counts meticulously gleaned from old packrat middens. I amused myself by examining these data to see whether elephants could be reintroduced into Arizona. Another color figure shows fantastic computer sequences on how the moon must have been formed by an impact between Earth and a Mars-sized billiard ball.

The description of the origin of life is a gem. Lunine's compelling prose springs out as lively as the quasi-stable whirlpools of life he describes (basically an autocatalysis model describing a mode of life existing before reproduction). An alternative model depicting an RNA origin of life is provided mainly for comic relief. Although the role of biology in forming Earth's almost explosive atmosphere covers several subsequent chapters, life is depicted as along for the ride, and the Gaia "biofeedback" theory is dismissed in a sentence.

Unfortunately, the origin of sentience, an event indisputably more profound than the origin of life, is not mentioned. However, the fossil evolution rise of humanity, particularly the Neanderthals, is wonderfully covered. Lunine mentions the "blitzkrieg" theory of his neighbor, Dr. Paul Martin, who postulates the extinction of American megafauna, such as the great elephants and saber-tooths, as being the result of the invasion of "native" Americans with spears. A nice contrast to the increase in American bio-diversity that accompanied the post-Columbian invasion of technologically advanced humans.

Lunine was identified by Time magazine as one of its 1994 "50 for the Future" list of emerging American leaders. Lunine himself would prefer the term "policy-maker" to leader, in the sense of presenting knowledge that self-led individuals can organize into principles of purposeful and long range action. The power of a comprehensive book such as this is that current issues such as global warming can be put in the perspective of past "atmosphere crises" of Earth, such as the super-high greenhouse prevailing at the end of the dinosaur era.

The penultimate chapter, titled "Limited Resources" fails this potential, being anecdotal without the factual rigor of the preceding chapters. (I was told that this chapter was written at the last minute at the request of the publisher.) Lunine starts by treating limited resources and overpopulation as arbitrary assertions, in defiance of his tradition of listing the assumptions of every dating method or limitations of climate modeling.

On the plus side, Lunine does take a rational stand against the Luddites. But where are the charts on air pollution, famine frequencies, human fertility, wetland or forest land acreage, etc. over time? The charts that do appear, on projections of population, energy use, kilos of grain per person, and "undiscovered" oil, have none of the error bars, validation, or context of previous chapters. Bemoaning the tiny amount of land urbanized each year to support farmers moving to the cities as a result of a world-wide food glut is an example of the surreal non-sequitor grab-bag of alarmist insinuations of which fill this chapter.

Particularly nasty is the bromide that less industrialized nations need a "reasonable" standard of living, with the implication that the U.S., (which creates most of the resources that feed and run the world), somehow deprives them of this even as the U.S. demonstrates the technological and political blueprints on how to achieve abundance. Since humans are too greedy or stupid to be allowed the freedom to despoil their own nest, only coercive regulation, or supra-governmental "cooperation" is required to tell their citizenry what is in their own best interests at gun-point. The nadir of these politics is an inexcusable sanction of coercive sterilization in China.

Other than the coverage of our most recent millennium, Lunine has written a tightly integrated and ambitious book. Particularly evocative is the imagery of the continents, floating and jostled into each other like froth on the churning oceanic plates of the Earth, teeming with a surprisingly robust and assertive biological component, laughing yet seesawing through cosmic disasters, extinctions, and self-induced crises of a scale that reduces the palimpsest of human intervention to ripples from a plunked stone.

This beautiful and vigorous accomplishment surmounts what has heretofore been a dry subject, and it literally groundbreaks the placement of our planet and ourselves in the objective context of existence and history.

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Summary: perfect book for reference
Review: If you're looking for a book that is a great read and even a better reference book about the geosciences, this is the one. I refer to it often in my scientific education. The references at the end of each chapter are also a great way for people to get further information on each subject, if they need it.