As the world grapples with climate change, a new report by the American Physical Society offers a glimmer of hope in the form of carbon dioxide removal technologies. But can physics truly save us from the devastating impacts of global warming?
Human activities continue to pump billions of tons of carbon dioxide into the atmosphere each year, raising global temperatures and driving extreme weather events. As countries grapple with climate impacts and ways to significantly reduce carbon emissions, there have been various efforts to advance carbon dioxide removal (CDR) technologies that directly remove carbon dioxide from the air and sequester it for long periods of time.
Climate change refers to significant long-term changes in the global climate patterns.
It is primarily caused by human activities that release greenhouse gases, such as carbon dioxide and methane, into the atmosphere.
These gases trap heat from the sun, leading to a rise in global temperatures.
According to NASA, the average global temperature has risen by about 1°C since the late 1800s.
This warming trend is causing more extreme weather events, sea-level rise, and altered ecosystems.
A new report by the American Physical Society, led by MIT physicist Washington Taylor, provides an overview of the major experimental CDR approaches and determines their fundamental physical limits. The report focuses on methods that have the biggest potential for removing carbon dioxide, at the scale of gigatons per year, which is the magnitude that would be required to have a climate-stabilizing impact.
CDR technologies are not without their challenges. The report highlights two main approaches: cyclic and once-through processes. Cyclic processes, such as chemical ‘direct air capture‘ (DAC), use a material that captures carbon dioxide and can be reused multiple times. However, these systems are subject to the second law of thermodynamics, which sets an energy constraint. For example, the absolute minimum amount of energy required to capture a gigaton of carbon using DAC is comparable to the total yearly electric energy consumption of the state of Virginia.
Once-through processes, such as enhanced rock weathering, accelerate natural processes that absorb carbon from the atmosphere. However, these systems require large amounts of physical material, air movement, and energy. For example, capturing a gigaton of CO2 using enhanced rock weathering would require roughly a billion tons of rock.
The report concludes that CDR is not a magic bullet, but also not a no-go. While it will be expensive and require significant amounts of energy and materials to achieve large-scale CDR, the report argues that research and development on CDR methods should be selectively and prudently pursued in addition to aggressive emissions reductions.
The main message from a policy perspective is that an economic and policy framework that incentivizes emissions reductions and CDR in a common framework would allow the market to optimize climate solutions. Since it is often easier and cheaper to cut emissions than to remove atmospheric carbon, understanding the challenges of CDR should motivate rapid emissions reductions.
According to Taylor, ‘scientifically we understand what it will take to reduce emissions and to use CDR to bring CO2 levels down to a slightly lower level.‘ He remains optimistic that humanity has the potential to solve these problems, but emphasizes that finding common ground is crucial to taking actions as a society that benefit both humanity and the broader ecosystems on the planet.
