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Limits to Growth – Bacteria in a Bottle

Retired physics professor Al Bartlett (to whom the GrowthBusters movie was dedicated), is world famous both for his Laws Related to Sustainability and his lecture about exponential growth. Audiences frequently tell me this segment from GrowthBusters is one of the most powerful. Share it with your lab partners (for the experiment we’re starting tomorrow, see below). And share it with everyone who needs to grasp this concept.

We’re one day away from launching our Limits to Growth 40th anniversary campaign. Be sure to check back tomorrow (subscribe to this blog at the right to be sure you don’t miss it). That’s also when you’ll start your exponential growth demonstration/experiment, so be sure you’ve got the supplies ready (see yesterday’s post). You’re invited to share your experiment experience with us as you go along (written comments, photos, even video), so consider chronicling your progress in one or more of these ways.

Exponential growth is an important concept for us all to grasp. Once world leaders and their economic advisors really understand it, public policy will shift in a much wiser and more sustainable direction. Exponential growth is the reason we get curves shaped like hockey sticks. Today’s 1% annual global population growth rate may seem modest to you. But, thanks to the power of compounding, a population growing 1% each year will double in 70 years, quadruple in 140 years, and octuple 70 years after that.

3% Annual Economic Growth

3% Annual Economic Growth

This math frequently comes up when we’re talking about population. But when the subject is economic growth – not so much. In GrowthBusters I point out an economy growing at a fairly typical 3% annual rate will be one billion times its current size in just 720 years. The graphic above shows just the beginning of a curve that turns into the hockey stick from hell.

You can also follow along on facebook as we perform this experiment and honor Limits to Growth on its 40th anniversary.

Dave Gardner

Dave Gardner is the director of the new documentary, GrowthBusters: Hooked on Growth, which uncovers the cultural forces that keep us pursuing growth in the face of overwhelming evidence we’ve outgrown the planet.

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Comments (2)

  • Avatar

    Terry A McNeil


    The 18th Sustainability Law while true could also entail the existential reality, that in all probalilty, human extinction WILL OCCUR sooner or later. Our collective actions contribute to whether this final event is reached rapidly or slowly.

    This leads to a philisophical question as to whether the human species roaming this planet for 250,000 or 300 million years really matters against the time clock of infinity and relevance of the universe?.Considering futher that even 300 miliion years against such measures may be illustrated as a mere drop in the ocean of time.

    For certain many more quesstions,ithoughts and possibilities may be drawn from this assertion of inevitable extinction. And could possibility go on forever…


  • Avatar

    Veeraragavan N


    Did you select 300 million years specifically? Because that’s the time the earliest reptiles started appearing on the earth. Human being are a lot younger than that & especially civilized ones with advanced cognition & linguistics capabilities which is less 20,000-40,000 years.


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