In Defense of Net Zero

The concept of net zero has recently received a lot of negative attention in the public discourse. Some of this is motivated by genuine concern for the economic costs of the energy transition. Some is driven by an anti-clean energy agenda.

In this short post, I will explain why I believe net zero to be the correct analytical framework for climate action and the energy transition. To summarize, we cannot avoid climate disruption without reaching net zero. Even if the cost of net zero is substantial, the path of inaction is more expensive and riskier.

1. What is net zero?

The basic idea of net zero is simple: the greenhouse gases that human activity adds to the atmosphere must be balanced by compensating reductions. When this steady state is achieved, global temperatures no longer increase because of humans.

To achieve net zero, the global economy must go through two transformations:

· The top priority is to reduce greenhouse gas emissions through renewable energy, other clean energy sources, energy efficiency, and replacing non-carbon greenhouse gases with sustainable alternatives.

· While these reductions will do most of the work, the last ~10% of greenhouse gas emissions will be very hard to mitigate. Problem areas might include deforestation, aviation, shipping, and heavy industry. To deal with the remaining greenhouse gases, we need compensating activities such as carbon capture & storage, afforestation, or direct air capture of carbon dioxide.

The genius of net zero is that it provides a way to stop global warming without the impossible task of reducing greenhouse gas emissions to zero.

Why is it not enough to reduce greenhouse gas emissions by 90% or so? Carbon dioxide stays in the atmosphere for centuries. If we continue to generate net positive emissions, global warming will continue, if perhaps at a slower pace. That is not enough to avoid climate disruption according to climate scientists.

2. Inaction is more costly and riskier than net zero

Net zero has been criticized as overly expensive. This criticism is correct insofar the clean energy transition will cost trillions of dollars every year at the global level. This is not a trivial amount of money.

But what is the alternative? If we do not achieve net zero, then we are looking at global warming well in excess of 2 degrees Celsius. Climate scientists have found that such warming in this century will cause massive economic ...