Hanna Ryan, Abdulla Ahmed, Xu Yangyang, Victor David G
Center for Energy Research, University of California San Diego, La Jolla, CA, 92093, USA.
Deep Decarbonization Initiative, University of California San Diego, La Jolla, CA, 92093, USA.
Nat Commun. 2021 Jan 14;12(1):368. doi: 10.1038/s41467-020-20437-0.
Though highly motivated to slow the climate crisis, governments may struggle to impose costly polices on entrenched interest groups, resulting in a greater need for negative emissions. Here, we model wartime-like crash deployment of direct air capture (DAC) as a policy response to the climate crisis, calculating funding, net CO removal, and climate impacts. An emergency DAC program, with investment of 1.2-1.9% of global GDP annually, removes 2.2-2.3 GtCO yr in 2050, 13-20 GtCO yr in 2075, and 570-840 GtCO cumulatively over 2025-2100. Compared to a future in which policy efforts to control emissions follow current trends (SSP2-4.5), DAC substantially hastens the onset of net-zero CO emissions (to 2085-2095) and peak warming (to 2090-2095); yet warming still reaches 2.4-2.5 °C in 2100. Such massive CO removals hinge on near-term investment to boost the future capacity for upscaling. DAC is most cost-effective when using electricity sources already available today: hydropower and natural gas with renewables; fully renewable systems are more expensive because their low load factors do not allow efficient amortization of capital-intensive DAC plants.
尽管各国政府极有动力减缓气候危机，但可能难以对根深蒂固的利益集团实施代价高昂的政策，这就导致对负排放的需求更大。在此，我们将战时式的直接空气捕获（DAC）快速部署建模为应对气候危机的一项政策措施，计算所需资金、净二氧化碳清除量及气候影响。一项紧急DAC计划，每年投资占全球GDP的1.2% - 1.9%，到2050年每年可清除2.2 - 2.3 GtCO₂，到2075年每年可清除13 - 20 GtCO₂，在2025年至2100年期间累计可清除570 - 840 GtCO₂。与排放控制政策遵循当前趋势的未来情景（SSP2 - 4.5）相比，DAC大幅加速了净零二氧化碳排放的到来（至2085 - 2095年）以及变暖峰值的出现（至2090 - 209年）；然而到2100年变暖仍会达到2.4 - 2.5°C。如此大规模的二氧化碳清除取决于近期投资，以提升未来扩大规模的能力。当使用目前已有的电力来源时，DAC最具成本效益：水电和天然气搭配可再生能源；完全可再生系统成本更高，因为其低负载率无法实现资本密集型DAC工厂资本的有效摊销。
