About GOAL-A

Project Summary

Atmospheric CO2 concentrations and climate state are regulated by the global carbon cycle. A key component of the global carbon cycle is the conversion of solid minerals and atmospheric CO2 to bicarbonate through the process of chemical weathering. Dissolved bicarbonate from chemical weathering is then transported by rivers to the global ocean, where it joins a massive pool of dissolved inorganic carbon. On millennial time scales bicarbonate from terrestrial chemical weathering builds up in the ocean leading to the precipitation of bicarbonate back to a solid carbonate mineral. This cycling of inorganic carbon is closely tied to the global water cycle, as water evaporates off the surface oceans, is delivered to continents as rainfall, and is then sent back to the ocean with the products of chemical weathering via rivers. Thus the inorganic portion of the global carbon cycle connects all the major Earth reservoirs.

A number of negative emissions technologies propose to accelerate the conversion of atmospheric CO2 to bicarbonate on land by spreading weatherable minerals across the land surface, referred to as enhanced rock weathering (ERW), or to catalyze the uptake of CO2 from the atmosphere to the surface ocean through modification of surface ocean chemistry, referred to as ocean alkalinity enhancement (OAE)., These potential negative emissions technologies hold significant promise, with current estimates indicating that they could sequester 10’s of gigatons (Gt = 109 tons) of CO2 per year. They are also very durable compared to most other negative emissions technologies, as they mix into a very large pool of ocean alkalinity, with most estimates of durability being exceeding thousands of years. For ERW, the infrastructure to spread these minerals already exists as farmers already spread large quantities of weatherable minerals to maintain optimal soil pH for growing crops. Both ERW and OAE can increase the alkalinity of the ocean, with the potential to directly offset ocean acidification, which is proposed to have massive negative impacts on the health of the Earth’s ocean ecosystems.

Currently there is no way to assess the end-to-end impacts of ERW or the combined impacts of ERW and OAE, which in reality are likely to be pursued in parallel. This is due to a lack of model frameworks that can connect and integrate the inorganic carbon cycle across all of Earth’s domains. Since both ERW and OAE lead to the loading of alkalinity to coastal and open ocean basins, this represents a major gap in our ability to forecast ocean impacts of these practices. Furthermore, cross domain fluxes of water and inorganic carbon via the atmosphere and rivers create important feedbacks that impact rates of carbon uptake and leakage that can only be evaluated through a fully connected global model framework.

Here we propose to create a fully connected global inorganic carbon model. The proposed team has expertise in modeling soils, inland waters, coastal regions, the open ocean and global moisture transport. We propose model development around inorganic carbon in all of these domains. This within-domain development will help society determine the efficacy of, and help to optimize, these technologies. Furthermore, we propose to connect these domains in order to close Earth’s water and carbon budget with a focus on how climate change and adoption of these negative CO2 technologies at broad scales will impact ocean acidification, biogeochemical flows, and climate change, three of Earth’s “planetary boundaries”. We believe other DOE “Earth shots” that impact these planetary boundaries or involve cross domain flows of materials will benefit significantly from the proposed work.

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