Johanna Hoffman, a member of our Emerging Fellows program detects technologies that could be likely helpful to climate change challenge. The views expressed are those of the author and not necessarily those of the APF or its other members.

Some people call them a shot in the dark. Others insist they’re escapist fantasy. For others, they’re the saviors we can’t ignore. Regardless of what words you use, negative emissions technologies demand our attention. An emerging area of research and development, they continue to dangle real potential to change the climate adaptation game.

In case you’ve yet to hear of them, here’s a brief definition. Also known as ‘carbon dioxide removal systems,’ negative emissions technologies are tools to extract CO₂, one of the biggest contributors to global warming, from the atmosphere.

Their allure has multiple dimensions. Many acknowledge that as we move towards a net-zero or even net-negative world, halting all carbon emissions both immediately and in the long term is a daunting task. The primary avenues for achieving those goals lie in widespread adoption of more renewable energy and green technology systems. Due to widespread political, economic and cultural issues, however, many carbon drawdown plans recommend continuing certain sources of carbon use for certain periods of time, in the hopes of enabling smoother transitions. That carbon emitted now could be extracted from the atmosphere later presents a comforting prospect, that we could live in a world where the process of addressing climate change could be achieved through less disruptive means.

While they sound too good to be true, negative emissions technologies are no fantasy. They currently exist. From bioenergy generation to direct air capture to biochar, these tools have been proven to extract atmosphere CO_2. At present, however, the processes are very energy intensive, making the tools prohibitively expensive as blanket go-to strategies for effective sequestration at actionable scales.

New research could change that. For example, Wil Srubar, and Assistant Professor at the University of Colorado at Boulder, has recently developed techniques to replace cement in concrete with cyanobacteria. As construction is one of the most heavily polluting industries, and cement in particular emits huge amounts of of CO₂ every year, this innovation presents opportunities for real positive change. Because cyanobacteria is a common class of microbe that captures energy through photosynthesis, this new type of concrete passively absorbs carbon from its surroundings. If the technology is scaled - and it is receiving considerable attention from large scale funders already - it could create buildings and cities capable of becoming not just carbon neutral but carbon negative. Imagine a city where all substrates and surfaces function like a forest, with carbon sinks cropping up wherever human development exists.

Despite its many potential benefits, the technology would be no silver bullet. Indeed, it could feasibly enact even more complex and dangerous repercussions. Introducing living organisms into uncontrolled urban environments stands the very real chance of creating lethal externalities, from the emergence of previously unseen diseases to new vulnerabilities in essential support systems. Were bio-hacked cyanobacteria to become the building blocks of our cities, it stands to reason that new, uncontrollable mutations might well cause unanticipated and widespread havoc, both domestically and across the globe.

Yet perhaps the most compelling risk that negative emissions present is one of human complacency. If we find ways to extract carbon from our atmosphere, what’s to prevent us from continuing to produce more carbon, methane and other problematic substances, failing to curb the practices that result in greater climatic uncertainty in the first place?

To provide more help than harm, negative emissions must be implemented in conjunction with more cohesive energy efficient and net carbon neutral efforts across our borders. Technology alone is not enough to save us. With restraint, international coordination and thoughtful implementation, we stand a far better chance.