In this pivotal chapter, I examine the 1.5°C emissions pathways urged upon us in the 2018 IPCC SR15 report. I compare those steeply plunging emissions pathways to emissions predictions over the next 30 years made by McKinsey and Bloomberg to demonstrate that the IPCC pathways are unlikely to obtain. To devise what seems a more likely scenario, I utilize the McKinsey/Bloomberg scenarios through 2050 and append to them subsequently the sort of emissions plummet that the IPCC would recommend we commence in 2021. Even in 2050, an emissions nose-dive seems an optimistic scenario but it illustrates a pathway to Net Zero Emissions by 2084. I then translate that emissions pathway into a temperature outcome that shows an increase of roughly 2.7°C above pre-industrial temperatures in the Net Zero year. More importantly, I illustrate that after Net Zero, temperatures and therefore resulting climate damages plateau rather than decline. Worse yet, sea levels would continue to rise for centuries. Having undertaken the enormous sacrifices necessary to achieve Net Zero, I assert that future generations are unlikely to find that state of affairs acceptable. They will demand further action to reduce temperatures and climate damages. They will demand climate intervention.

Geoengineering describes a range of technologies that attempt to mitigate the effects of global warming caused by increasing greenhouse gas concentrations. Some geoengineering approaches remove carbon dioxide from the atmosphere. These are not controversial, but they are currently too expensive to serve as a viable option. The most cost-effective technique, called solar radiation management, aims to reflect sunlight by continuously dumping large quantities of sulfate aerosols into the stratosphere, much as a volcanic eruption would. But geoengineering attempts to address the symptoms of the disease of global warming rather than the disease itself, which will persist as long as carbon emissions continue. Computer models of climate are essential to assess the efficacy of any geoengineering approach, because large-scale physical experimentation would be dangerous. However, the information that is most crucial for us to know – the impact geoengineering would have on regional climates – is something models have trouble predicting.