Abandon hype in climate models

The economic models that are used to inform climate policy currently contain an unhealthy dose of wishful thinking. Technologies that remove carbon dioxide from the air are assumed in the models that avoid dangerous climate change - but such technologies do not yet exist and it is unclear whether they could be deployed at a meaningful scale.

The scenarios modelled for the IPCC's Fifth Assessment Report assume the large-scale deployment of technologies that achieve negative emissions that draw down carbon dioxide from the atmosphere and permanently store it. But whether such proposed methods could be deployed at a material scale is unproven. It would be more prudent to exclude these techniques from mitigation scenarios used by the IPCC, unless and until we have sufficient evidence of their availability and viability to support their inclusion.

Most of the modelled emissions pathways limiting warming to 2 C (and all the ones that restrict the rise to 1.5 C) require massive deployment of Biomass Energy with Carbon Capture and Storage (BECCS). This involves growing biomass which is used to generate power and geologically sequestering the carbon dioxide produced. While the constituent steps of this process have been demonstrated, there are but a few, small, examples of the combined process. To rely on this technique to deliver us from climate change is to demonstrate a degree of faith that is out of keeping with scientific rigour.