Scientists once ridiculed the idea of a living planet. Not anymore.
Every year the nearly 400 billion trees in the Amazon rain forest and all the creatures that depend on them are drenched in seven feet of rain — four times the annual rainfall in London. This deluge is partly due to geographical serendipity. Intense equatorial sunlight speeds the evaporation of water from sea and land to sky, trade winds bring moisture from the ocean, and bordering mountains force incoming air to rise, cool and condense. Rain forests happen where it happens to rain.
But that’s only half the story. Life in the Amazon does not simply receive rain — it summons it. All of that lush vegetation releases 20 billion tons of water vapor into the sky every day. Trees saturate the air with gaseous compounds and salts. Fungi exhale plumes of spores. The wind sweeps bacteria, pollen, leaf fragments and bits of insect shells into the atmosphere. The wet breath of the forest, peppered with microbes and organic residues, creates ideal conditions for rain. With so much water in the air and so many minute particles on which the water can condense, rain clouds quickly form.
The Amazon sustains much more than itself, however. Forests are vital pumps of Earth’s circulatory system. All of the water that gushes upward from the Amazon forms an enormous flying river, which brings precipitation to farms and cities throughout South America. Some scientists have concluded that through long-range atmospheric ripple effects the Amazon contributes to rainfall in places as far away as Canada.
The Amazon’s rain ritual is just one of the many astonishing ways in which living creatures transform their environments and the planet as a whole. Much of this ecology has only recently been discovered or understood. We now have compelling evidence that microbes are involved in numerous geological processes; some scientists think they played a role in forming the continents... (continues)
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