Assessing carbon dioxide removal through global and regional ocean alkalinization under high and low emission pathways

Andrew Lenton, Richard J. Matear, David P. Keller, Vivian Scott, Naomi E. Vaughan

Research output: Contribution to journalArticlepeer-review

Abstract

Atmospheric carbon dioxide (CO2) levels continue to rise, increasing the risk of severe impacts on
the Earth system, and on the ecosystem services that it provides. Artificial ocean alkalinization (AOA) is capable
of reducing atmospheric CO2 concentrations and surface warming and addressing ocean acidification. Here, we
simulate global and regional responses to alkalinity (ALK) addition (0.25 PmolALK yr􀀀1) over the period 2020–
2100 using the CSIRO-Mk3L-COAL Earth System Model, under high (Representative Concentration Pathway
8.5; RCP8.5) and low (RCP2.6) emissions. While regionally there are large changes in alkalinity associated with
locations of AOA, globally we see only a very weak dependence on where and when AOA is applied. On a
global scale, while we see that under RCP2.6 the carbon uptake associated with AOA is only 60% of the total, under RCP8.5 the relative changes in temperature are larger, as are the changes in pH (140 %) and aragonite
saturation state (170 %). The simulations reveal AOA is more effective under lower emissions, therefore the higher the emissions the more AOA is required to achieve the same reduction in global warming and ocean acidification. Finally, our simulated AOA for 2020–2100 in the RCP2.6 scenario is capable of offsetting warming and ameliorating ocean acidification increases at the global scale, but with highly variable regional responses.
Original languageEnglish
JournalEarth System Dynamics
DOIs
Publication statusPublished - 6 Apr 2018

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