In my view, the best article ever written on sustainability is by Nobel-prize winning economist Robert Solow; his 1991 speech is entitled, “Sustainability: An Economist’s Perspective” (It is hard to track down on the internet but it is included in many volumes on environmental economics; I highly recommend it to anyone interested in sustainability).
In the speech Dr. Solow lays out the key tenets of sustainability, as well as its contradictions. He defines sustainability as the societal outcomes that allow future generations to be at least as well off as people are today. He makes it clear that sustainability does not require saving specific resources, only ensuring that there is sufficient capital (a combination of human, physical, and natural) for future generations to create living standards at least as good as ours (but in ways that match their preferences, which we have little way of knowing).
Without getting into a long discussion on weak versus strong sustainability, one of the ongoing debates is the extent to which these three types of capital are substitutable. In general, environmentalists tend to think that many forms of unique natural capital (e.g. a national park) are not substitutable with, for example, an increased number of hospitals (i.e. physical capital), and probably most economists would agree, although the discussion gets trickier when we turn to less unique environmental resources.
The key insight that Solow raises is that sustainability is at its core about leaving sufficient capital for future generations, and therefore, our decisions today about how much we consume versus how much we invest are the key drivers of sustainability.
But Solow had another profound insight. He pointed out that it is morally problematic to worry about the welfare of people who are yet to be born while so many people currently suffer in dire poverty. Putting aside money to ensure that future generations are well off creates a moral dilemma if this money could be used to help people today. But this raises a further paradox; much of what people need today is increased consumption (stoves, refrigerators, more food, etc.) when sustainability generally favors investment in capital. To be fair, I think Solow’s exaggerated this tension because the world’s poor need plenty of investment in capital in the form of infrastructure, medicines, schools, etc. Nonetheless, Solow’s insight remains; there is an uneasy tension between wanting to help future generations while billions suffer from a lack of resources today. In essence, many forms of poverty are quite “sustainable”, which should give pause to everyone enamored with this concept. In fact, many environmentalists have raised alarms as the Chinese and Indians have vastly increased their material standard of living because of the environmental impacts, which speaks exactly to this point.
Enter global warming; how does sustainability inform the discussion?
1. If the worst-case scenarios of global warming are likely then we can say with some confidence that current behaviors (to the extent that they are contributing to global warming- this is key) are putting us on an unsustainable path, because they are going to make people in the future worse off than we are today (and we should enact major changes in our behavior). The reason I put the caveat in above is that even in the worst-case scenario, if changing our behavior would do little to actually prevent global warming, and at the same time make us much poorer, then doing little to stop it would still be a better strategy.
2. If the consensus among scientists points to an extremely low probability of the worst-case scenarios, then we are forced back into a situation where we have to balance the costs and benefits of changes in our behavior against the backdrop of how much our behavior is likely to affect the medium to long-term climate trends.
3. Regardless of which scenario we are in, global warming presents us with large distributional and equity issues because the richer nations by and large have the capacity to deal with global warming while the poorer nations do not. Again, the question as to whether helping poorer nations deal with global warming may be cheaper than averting it needs to be examined carefully.
In summary, even through a sustainability lens it is ambiguous whether we must act now to do whatever we can to avert global warming. Given the massive cuts in carbon emissions (in the realm of 70%) that many think would be required to prevent any further warming, one doesn’t have to be a pessimist to believe that given current trends the probably of this happening is extremely low, and therefore, as I have mentioned previously, mitigation strategies may be preferable.
In the end, global warming presents us with very tough choices based on a huge range of scenarios that are highly uncertain. People in the future may look back at us one day and condemn us for our inaction, or they may be grateful that we didn’t spend so much on the problem, depending on how it plays out.