(Extracted from The World Without Us, Alan Weisman)

Elsewhere on Earth, on former croplands that humans tended for millenia, warming trends will create variations of today's Amazon.  Trees may cover them with vast canopies, but the soils will remember us.

In the Amazon itself, charcoal that permeates frequent deposits of rich black soil call terra preta suggests that, thousands of years ago, paleo-humans cultivated wide swatches of what we think of today as jungle primeval.  Slowly rather than burning trees, they ensured that much of their nourishing carbon was not expelled into the atmosphere but was instead retained, along with nitrogen, phosphorus, calcium and sulfur nutrients--all packaged in easily digested organic matter.

This process has been described by Johannes Lehmann, the latest of a lineage of Cornell University soil scientists who have studied terra preta nearly as long as the heirs to Rothamsted founder John Lawes have experimented with fertilizer. The charcoal-enriched soil, despite incessant use, never gets depleted.  Witness the lush Amazon itself: 

Lehman and others believe that it sustained large pre-Columbian populations, until European diseases reduced them to scattered tribes who now live off nut groves planted by their ancestors.  The unbroken Amazon we see today, the world's largest forest, rushed back so quickly across rich terra preta that European colonists never realized it was gone.

"Producing and applying bio-char," writes Lehmann, "would not only dramatically improve soil and increase crop production,but also could provide a novel approach to establishing a significant, long-term sink for atmosphere carbon dioxide."

In the 1960s, British atmospheric scientist, chemist, and marine biologist, James Lovelock proposed his Gaia hypothesis, which describes the Earth as behaving like a super-organism, its soil, atmosphere, and oceans composing a circulatory system regulated by its resident flora and fauna.  He now fears that the living planet is suffering a high fever and that we are the virus.  He suggests we compile a user's manual of vital human knowledge (on durable paper, he adds) for survivors who may sit out the next millenium huddled in the polar regions, that last habitable places in a super-heated world, until the ocean recycles enough carbon to restore a semblance of equilibrium.

If we do so, the wisdom of those nameless Amazonia (and now Canadian) farmers should be inscribed and underlined so that we might attempt agriculture a little differently next time around.