jueves, noviembre 24, 2011

Growth Has an Expiration Date


Guest Blog/

Indefinite growth on a finite planet is impossible. Few would argue the truth of this statement in physical terms, but most believe that economic growth is immune to such a claim, because—the story goes—economics can be decoupled from physical throughput via efficiency improvements, transformative technology/innovation, and increased activity in low-resource-use “service” industries. All of these things happen, and are real. But I argue in a series of blog posts on Do the Math that these notions, too, have limits. I also explore what this means for the concept of sustainability.
We begin with a startling illustration that continued energy growth at 2% per year has us consuming energy at a rate equivalent to the power output of all 100-billion stars in the Milky Way galaxy inside of 2500 years! Furthermore, no matter what the energy technology, the Earth’s surface would become so hot that water boils in a little over 400 years, and we reach the surface temperature of the sun in 1000 years. This is not global warming from CO2, but straightforward thermodynamics, and is an inescapable consequence of a continued growth trajectory on Earth. There are many reasons why this won’t happen—which is to say that we will end physical growth (in energy, for instance) within a century or two at the latest. Fusion (even the “cold” variety) is not exempt.
Next is a demonstration that economic growth cannot continue indefinitely against a constant energy supply. This starts with the observation that efficiency cannot be increased arbitrarily. We’ve got maybe a factor of two to gain, yet, at a typical rate of 1% per year. Nor can low-intensity activities continue to grow forever in a flat-energy world, because such things will saturate the economy—some fraction of which must still rely on a non-growing energy base. Some decoupling can extend economic growth for a time, but complete decoupling is not a real possibility. More >

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