The Promise of Climate Mitigation and Restoration Through Transformative Technologies

After decades of procrastination in addressing the carbon dioxide emissions at the root of climate change, the world is now firmly on an overshoot trajectory. Not only will the dumping of carbon dioxide into the atmosphere have to stop, but the excess carbon, which is mainly the waste product from fossil fuel consumption, will have to be mopped up as soon as possible. Time is short; the irreparable harm from climate change will rise with the duration and height of the overshoot. Technologies are urgently needed to lower atmospheric carbon dioxide concentrations by about 100 ppm, which is equivalent to about 40 years of current emissions at 40 Gt CO2 per year. Can such technologies be developed? The answer is a qualified yes. Affordable natural processes for the capture or storage of carbon already exist and thus allow for immediate deployment. At issue is their scalability, with strong evidence that the full scope of negative emissions would severely strain capacity. On the other hand, direct air capture technologies, while still in their infancy are not limited by scale but by cost constraints. Various approaches have been demonstrated, but current deployment is still miniscule. Costs would have to come down roughly five-fold, to below $100/ton CO2, for direct air capture to compete in current commercial CO2 markets. Typical learning curves in mass manufacturing suggest that this goal could be reached well before direct air capture would satisfy commercial CO2 demand. Since direct air capture would have to scale up a million-fold to have a climate impact, its asymptotic floor in cost is impossible to predict. The cost of photovoltaic power dropped more than 100-fold as it moved from the kilowatt scale to the Gigawatt scale. Past success is no guarantee for future results, yet the value of demonstrating at the Megaton scale an affordable and scalable negative emissions technology appears to far exceed its cost.