Sampriti Roy, University of Calcutta
“The era of procrastination, of half measures, of soothing, and baffling expedience of delays is coming to its close. In its place, we are entering a period of consequences.” -Winston Churchill
Today we find growing consensus among scientists, local and regional governments, and millions of citizens in accepting climate change as a major threat to human society- a threat that demands action. One major idea in taking action towards climate change has been recently put forward by scientists at the University of California San Diego- a program (massively funded) to deploy systems called Direct Air Capture (DAC) scrubbers that remove CO2 from the ambient air directly and sequester it safely underground. Economic and technological modelling of DAC is linked to climate models that calculate the effects of these deployments on the level of atmospheric CO2 concentration and global mean surface temperature.
The study claims that the implementation of such a program could reverse the rise in global temperatures well before 2100, provided that implementation is with wartime-level funding.
But what’s so special about DAC?
- The authors prove DAC’s effectiveness (in wartime-like crash deployment situation) in removing CO2 emissions by providing the following statistics:
- if an emergency direct air capture program were to commence in 2025 and could receive an investment of 1.2–1.9% of global GDP annually, it has the following removal capacities:
- By 2050: 2.2–2.3 gigatons of CO2, and
- By 2075: 13–20 gigatons of CO2.
- Cumulative removal of CO2 form 2025-2100: 570-840 gigatons (which is in the league of figures suggested by the IPCC to meet targets of the Paris Agreement)
- DAC is energy extensive but unlike bioenergy with carbon capture and sequestration (BECCS), it seems to have no biophysical limits.
- DAC does not require extensive land-use changes and thus, does not compete with important sustainability goals such as maintaining food production and biodiversity.
- Attractiveness to policymakers: Though more expensive than many other mitigation measures related to climate, DAC may prove to be attractive to policymakers because:
- There is a high value of near-term DAC deployments—even if societies today are not yet treating climate change as a crisis. This is because near term deployments are found to improve the future scalability of a government
- Implementation costs would gradually fall as firms become experienced with technology.
- Deployments are said to be highly controlled by the stakeholders, i.e., governments and firms
- The carbon values are verifiable
- Opportunity for job creation
- The systems do not threaten any of the existing industries with economic competition.
Thus, when public pressures leave no room for avoiding action, DAC could prove to be useful in answering concerns if conventional mitigation proves to be economically or politically difficult.
But will DAC be enough?
According to the researchers, even if direct air capture is used to the extreme of its performance abilities as part of a “crisis deployment” plan, there would still be the need to take negative CO2 emissions seriously. Meeting climate goals, such as that of the Paris Agreement to keep average global temperature rise below 2 degrees C, requires not just preventing “new” emissions but also finding ways to remove “historical” emissions in the atmosphere.
Yes, a fleet of CO2 scrubbers receiving wartime-level funding could lead to slow warming, but “stopping” climate change will require deep cuts in our emissions. It is ultimately up to governments to adopt appropriate policies for emission mitigation and up to scientists to keep carrying out new and most importantly, holistic research related to the mitigation of the climate crisis- a crisis that with current practices is predicted to get only worse in the coming days.
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Source: Hanna, R., Abdulla, A., Xu, Y. et al. Emergency deployment of direct air capture as a response to the climate crisis. Nat Commun 12, 368 (2021). https://doi.org/10.1038/s41467-020-20437-0
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