This global population growth chart, from Steven Johnson’s post, blew my mind. It illustrates what happens when growth goes from linear to exponential.
In Steven Johnson’s words – “That’s the 6,000 year history of human population growth. You might notice, if you really squint your eyes, that something interesting appears to happen about 150 years ago. After millennia of slow and steady growth, human population growth went exponential. And that’s not the result of people having more babies—the human birth rate was declining rapidly during much of that period. That’s the impact of people not dying. And while that is on one level incredibly good news, it is also in a very real sense one of the two most important drivers of climate change. If we had transferred to a fossil-fuel-based economy but kept our population at 1850 levels, we would have no climate change issues whatsoever—there simply wouldn’t be enough carbon-emitting lifestyles to make a measurable difference in the atmosphere.
The key idea here is that no change this momentous is entirely positive in its downstream effects. Trying to anticipate those effects, and mitigate the negative ones, is going to take all of our powers of prospection.”
It also illustrates why I’m particularly interested in the technology adoption curves of solar energy and other renewable energy sources. In cases where the externalities (or second order impacts) are positive, great things happen when growth goes from linear to exponential.
