Here’s your weekly Science Matters column by David Suzuki with Faisal Moola.

It’s all about the biosphere

All life exists is the biosphere, the zone of air, water and land that
envelops the planet. We often think of the atmosphere as extending to
the heavens when in fact, it is only about ten kilometers thick. The
biosphere, astronomer Carl Sagan used to say, is as thick as a layer of
varnish painted on a basketball.  That is where all life flourishes.
Beyond it, there is only space.

Humanity
has become so numerous and powerful that we are now altering the
biological, physical and chemical makeup of the biosphere. Everything
we do has repercussions throughout it because everything is
interconnected. If, for example, we pour toxins into air, water or
soil, it’s clear that these same toxins will end up in us. This is
exactly what we learned from Rachel Carson when she wrote her
influential 1962 book Silent Spring, about the effects of the pesticide
DDT in the biosphere. Carson explained how DDT, sprayed onto farmers’
fields, killed insects as it was supposed to. But the pesticide also
had unintended effects, such as ending up in fish, birds and
mammals–including humans.

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