Alkalinity Research Voyage || ARVO

The Alkalinity Research Voyage (ARVO) is a scientific research initiative focused on ocean liming, a form of ocean alkalinity enhancement (OAE). Through two research voyages with CSIRO research vessel (RV) Investigator in Bass Strait, ARVO aims to improve understanding of the effectiveness and environmental implications of this approach in Australian waters.

Ocean alkalinity enhancement (OAE) refers to a group of novel CO₂ removal pathways that aim to increase the ocean's capacity to absorb and store atmospheric CO₂ by adding alkaline materials to seawater. These approaches seek to accelerate natural weathering processes that already help regulate Earth's climate.

Ocean liming is one form of ocean alkalinity enhancement whereby particulate minerals derived from limestone are added to the ocean to increase alkalinity. Analogous to the long-established practice of agricultural liming on land, the addition of lime neutralises seawater acidity to enable storage of additional CO₂ in seawater.

We focus on lime as a source of alkalinity because limestone contains hardly any other bioactive elements like trace metals or nutrients. It is therefore considered among the safest alkaline materials for ocean alkalinity enhancement.

Scientific and policy assessments indicate that carbon dioxide removal (CDR) is likely to be needed alongside emissions reductions to help address climate change and counteract hard-to-abate residual emissions. ARVO contributes to this broader scientific effort by evaluating one potential marine carbon removal approach.

No. CDR is fundamentally different to CCS. Carbon dioxide removal (CDR) aims to remove CO₂ from the atmosphere and store it in another carbon reservoir. The most common form of CDR is afforestation, which aims to store CO₂ in trees and forests. CCS takes CO₂ from a point source, for example a coal power plant, before it enters the atmosphere and stores the captured CO₂ underground.

No. Emissions reductions remain the most important and effective response to climate change. Carbon dioxide removal can only play a complementary role, needed for keeping global warming below 2°C because humans have already emitted too much carbon into the atmosphere. ARVO's research is focused on understanding whether ocean liming could contribute to carbon removal alongside rapid and sustained emissions reductions.

Reaching high amounts of carbon removal will require a portfolio of methods. Conventional CDR approaches, such as forestry, are critical components to this portfolio but cannot provide enough and store carbon only short-term. Due to these limitations, there is growing international interest in novel CDR approaches that could complement conventional methods.

No. ARVO1 will use limestone (CaCO₃) which does not readily dissolve in seawater. About 80% of the seafloor at Bass Strait is CaCO₃. The purpose of ARVO 1 is to test our delivery system and limestone dispersion. Furthermore, we do contained experiments on the deck of RV Investigator with more reactive lime (e.g. portlandite, Ca(OH)₂) to assess if these could be used safely for the second voyage, ARVO 2.

Maybe. If shipboard experiments during ARVO 1 find Ocean Liming to be without risk for the marine environment, we may add more reactive lime (e.g. portlandite, Ca(OH)₂) during ARVO2. In that case, the intention is that lime dissolves in the surface ocean to neutralise acidity, elevate alkalinity, and absorb atmospheric CO₂, without negative effect on the plankton community.

ARVO will apply state-of-the-art methodology including experimental incubations, natural analogue studies, and modelling to establish (1) if and how ocean liming affects marine communities, (2) if effects are observed, which organisms are "winners" and which ones are "losers" (3) implement findings into numerical simulations to assess wider environmental risks.

Laboratory studies, modelling and small-scale field research have improved understanding of ocean liming and other OAE approaches. However, larger-scale open-ocean research is needed to understand their effectiveness and environmental implications under more realistic conditions.

Bass Strait was selected for scientific and logistical reasons. Its relatively shallow waters, proximity to land and operational accessibility make it a suitable environment for studying ocean liming under realistic ocean conditions.

ARVO was developed in response to growing recognition by governments and international organisations that carbon dioxide removal may be needed, alongside emissions reductions, to help achieve global and Australian climate objectives. The project aims to provide independent scientific evidence to support informed decision-making.

ARVO aims to generate scientific evidence on the effectiveness and ecological effects of ocean liming. This evidence can help inform future decisions about whether the approach should be considered further or ruled out.

No. The selection of Bass Strait does not imply support for future deployment in the region. The location was chosen solely on the basis of scientific and logistical considerations for conducting the research.

Interest in ocean alkalinity enhancement is growing among governments, researchers and private companies. Independent academic research plays an important role in evaluating effectiveness, quantifying carbon removal, assessing environmental impacts and providing evidence that supports informed public and policy discussions.

No. ARVO is a scientific research project. The research team is studying ocean liming to assess its geochemical performance and environmental implications. The project is entirely neutral. It does not advocate for, or oppose, future deployment.

No. ARVO remains neutral on whether ocean liming or other OAE approaches should ultimately be deployed. Consistent with a precautionary scientific approach, the research is designed to rigorously test whether the method is effective and environmentally acceptable under realistic ocean conditions.

ARVO aims to build knowledge and trust through a commitment to neutrality, authenticity and transparency. Project communications focus on clearly explaining the purpose, methods, findings and limitations of the research, while ensuring that scientific evidence remains at the centre of discussions about OAE.

Scientific research benefits from engagement with stakeholders and the broader community. ARVO aims to provide accessible, evidence-based information that supports informed dialogue about marine carbon dioxide removal and its potential role in addressing climate change.

This research is supported by grants of sea time on RV Investigator from the CSIRO Marine National Facility.