Tristan and I have been discussing the importance of what people believe to the general issue of climate action. As such, it seems worth answering the key question behind this site: Why do I believe that we can move to a global economy based on renewable, zero-carbon sources of energy?
Why climate change is scary
Partly, my belief is rooted in the belief that doing so is necessary. That belief arises from two major sources. There is the degree to which I can evaluate the empirical evidence and related theories myself, and then there is the degree to which I think bodies like the IPCC and National Academy of Sciences are credible. To me, there seems to be many lines of evidence that reinforce one another. We have all kinds of observations â€“ from temperature records to species migration patterns to ice core samples â€“ that seem to demonstrate that greenhouse gas concentrations affect the climate, and that the climate can change in ways that would be very dangerous for humanity.
The fact that I find James Hansen credible enough to take seriously contributes to a significant extent to my concern about the possibility of runaway climate change. So does the fact that I haven’t seen any forceful rebuttal of his argument from credible scientists or organizations (though many object to his overt political advocacy).
Even if runaway climate change will not happen, it seems like there is strong evidence that warming of more than 5Â°C would have devastating consequences for humanity. Furthermore, it seems like that is the amount of warming we are likely to produce by the end of the 21st century, unless we change the development path the world is following.
Why renewables can do the job
All that makes me think the transition is necessary. I think it is possible because of the same combination of factors. I know enough to be able to see that the total incoming energy from sunlight far exceeds the current energy use of humanity. Furthermore, I know that we can convert that energy into forms that are useful for us. This belief is reinforced by calculations like those in David MacKay’s book. You can take the average amount of sunlight falling on a square metre of the ground in a day and combine that with the current efficiency of different means of converting that energy into a useful form and arrive at a sense of how many metres we need per person, to give people an amount of energy comparable to what they are using today.
On that basis, the transition to renewables looks feasible, though the scale of the thing is clearly massive. Producing a comparable amount of energy per person using renewables will probably require using a significant portion of the world’s total land area. That said, it is quite possible that the land can be used in multiple ways. We can farm between wind turbines, after all.
Why we can (hopefully) afford it
Finally, I believe that the transition is affordable almost completely on the basis of the testimony from others. I donâ€™t know enough â€“ and havenâ€™t put in enough time â€“ to produce an assessment comparable to that of the Stern Review on the Economics of Climate Change.
This last section is admittedly the weakest. I cannot say for sure that the transition will be affordable â€“ only that the best available evidence suggests that it is. Given that the transition is both necessary and possible, I think we should do it even in the less likely case that it is very expensive.
After all, climate change threatens to devastate human civilization, by undermining the stable climate upon which it depends. Even if making the transition to zero-carbon forms of energy was massively expensive – so much so that it was just about the only thing we could do aside from grow enough food to survive – the choice to make that investment would still be the best option open to us.