The world’s oceans absorb the largest share of carbon dioxide emitted by human activities, but humans do not completely understand how oceans absorb and store carbon, according to a new report by the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO).
The predictions about future changes in the planet’s atmospheric, oceanic and biological systems due to warming as analysed in Intergovernmental Panel on Climate Change (IPCC) reports are skewed by the incomplete understanding of ocean carbon.
This becomes a major roadblock for the reduction of greenhouse gases (GHGs) in the atmosphere or climate change mitigation and adapting to the changes occurring or climate change adaptation. “The ocean is one of our strongest climate allies, absorbing a large share of the carbon we emit. Yet we still lack a full understanding of how this natural defence functions - or how long it can endure,” said Khaled El-Enany, director general of UNESCO.
Around 25 per cent of current global emissions of GHGs are stored in the ocean. Current climate models give varied estimations for the amounts of carbon absorbed by the oceans with deviations between 10 to 20 per cent globally and even greater variations regionally, according to the Integrated Ocean Carbon Research Report authored by 72 experts from 23 countries.
The major reasons for these variations and uncertainties in models are limited availability of long-term data and gaps in the knowledge of how some of the ocean processes respond to warming and its consequences. This include the processes involved in the uptake of carbon in the oceans, shifting of planktons and microbes that affects long term storage of carbon, the exchange of carbon between the atmosphere and the oceans in coastal and polar regions.
The industrial activities in the oceans and geoengineering projects to capture and store carbon also influence the oceans’ natural absorption of carbon and need to be studied in detail.
All these factors highlight that humans are taking decisions around reduction of GHGs and adaptation to the impacts of warming such as extreme weather events and sea level rise without fully understanding the largest carbon sink, the oceans. “If the ocean absorbs less carbon in the future, more CO2 will remain in the atmosphere and accelerate global warming. This would have a direct impact on future emissions targets and national climate plans,” according to a press statement from UNESCO.
One of the most necessary steps to be taken to address the lack of understanding of ocean carbon is monitoring and data collection from all layers of the ocean. The other steps being modelling of ocean processes and coordination among nations of ocean-based policies.
“Coordinated global monitoring of ocean carbon absorption is therefore essential and urgent. This report reaffirms UNESCO’s commitment to supporting Member States in developing climate policies based on robust science to advance this goal,” said El-Enany.
The report called for the establishment of a global ocean carbon observing system with the help of satellites, automated sensor linked platforms and improved data collection from the surface, sub surface and deep ocean layers and better ocean carbon cycle modelling, especially from underrepresented regions. Scientists also need to carry out studies of biological processes and related experiments to understand them further and integrate them into models.
The report also asked for “the establishment of a transdisciplinary framework in ocean carbon research involving non-academic participants such as policy makers, managers, research communicators and indigenous knowledge holders, creating time and space to understand the contributions of the social sciences, the humanities and creative arts to the field of ocean carbon research.”