BACK in 1987, a panel headed by Sweden's Gro Harlem Brundtland defined sustainable development as growth that meets our needs without compromising the ability of future generations to meet theirs. This important new book from the International Energy Agency (IEA), a quasi-governmental agency, argues that that vision “has slowly evolved from a slogan for environmentalists into a guiding principle for public policy.”

Toward that end, the IEA has produced a how-to manual for pursuing more sustainable energy policies. Smog, acid rain and global warming, for example, are linked at least in part to man's use of fossil fuels. Notably, the work does not gloss over difficulties: it points out that liberalising power markets can make it harder to subsidise renewable energy sources, and that reducing emissions from transport might involve unpopular moves such as raising fuel taxes or ending perks like company cars.

LONG before the term became fashionable, Maurice Strong was a leading advocate of sustainability. The charming Canadian has seamlessly woven together a career in business with green activism and global policymaking. Though the book's writing can be plodding, his remarkable career and personal exuberance save it from dullness.

He helped pull together the Rio Earth Summit in 1992. That gathering saw the largest-ever collection of heads of state, including George Bush senior, launch the effort to tackle climate change. Ironically, its culmination—the Kyoto Protocol—has been rejected by Mr Bush's own son. Even so, Mr Strong hopes that the next big Earth Summit, to be held in Johannesburg in September 2002, can revive the goal of sustainable development, and he offers prescriptions for doing so.

KEITH TUTT also worries about the link between energy and sustainable development. His tone is evangelical: we are “fossil addicts”, he writes, caught in a “self-destructive spiral” threatening our survival. You do not, though, need to share Mr Tutt's vision of impending cataclysm to be interested in his profiles of inventors and entrepreneurs searching for clean, bountiful sources of energy.

Mr Tutt writes persuasively that these folk are by no means all quacks. His writing is clear, his reporting thorough and his arguments crisp. A good example of what “The Search for Free Energy” has to offer is his account of cold fusion. This was widely ridiculed as the scam of the century. But Mr Tutt lays out the reasoned case for why some version of this approach could play a role in the future of energy production.

THIS gem provides a contrast with those above, which look to a green future. Tim Flannery casts his gaze back. This is a literate, meticulously researched work on the environmental history of North America. Perhaps this book's greatest strength is Mr Flannery's ability to bring ancient, inanimate scenes to life. When he describes the great asteroid that crashed into what is now the Yucatan Peninsula (so ending the era of dinosaurs), he does so in such detail that the reader feels almost afraid.

Mr Flannery worries that a continent which has proved so accommodating and adaptable may have met its match in climate change. Controversially, he holds that North America “will feel its effects more violently and well in advance of other continents.”

NB: A review of “The Skeptical Environmentalist” by Bjorn Lomborg will appear in these pages later this month

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