Climate change is directly and indirectly influencing all aspects of human life globally. This has led to the implementation of a wide range of environmental regulations in both the European Union and Spain in recent years .

One of the most recent offers the possibility of offsetting greenhouse gas emissions with projects developed in marine ecosystems ( blue carbon ), which can now be added to the absorption initiatives developed in the terrestrial environment (green carbon) that have been carried out for several decades .

Interest in developing projects of this type is currently experiencing exponential growth . However, the challenges faced are numerous: legislative complexity, lack of specific regulations, scientific uncertainty, project and certification costs, and more.

All of these barriers are delaying the implementation of projects at the European and national levels, limiting all the climatic, ecological, and economic benefits they bring.

In 2023, the Andalusian Regional Government launched the first standard for the certification of blue carbon credits developed by a public administration at the European level. All the challenges it has faced, and continues to overcome, serve as a good example of the road ahead to ensure that this new opportunity for climate and environmental mitigation does not end up becoming a vague, empty fad.

The Andalusian standard: a pioneer in the European Union

One year after the approval of the Andalusian standard for the certification of blue carbon credits, the European Union published Regulation (EU) 2024/3012 , which seeks to establish a common framework for the certification of carbon removals throughout its territory.

In Spain, the recent approval of Royal Decree 214/2025 also contemplates the possibility of offsetting with blue carbon at the national level. However, to make this possible, the removals must be certified under a recognized standard . And, to date, the only existing national standard for this type of carbon is the Andalusian standard.

Due to the recent approval of this standard and its novelty, neither public administrations nor private developers are yet aware of this new offsetting option. This partly explains why no carbon absorption project has yet been implemented in a blue carbon ecosystem.

Despite this complex scenario, the launch of the first project based on this standard was announced in Cádiz just over a year ago. And recently, news broke about plans to launch another blue carbon absorption project, also in degraded salt flats in the Bay of Cádiz.

Complex barriers to overcome

The location where these projects are being developed, shallow coastal areas, presents a highly complex regulatory framework, involving multiple public administrations with diverse responsibilities. Furthermore, these areas are often subject to different environmental protection regulations, delaying and complicating administrative procedures. Furthermore, these areas fall under the category of public maritime terrestrial domain (PMTD), in which the ownership of the absorptions generated by a developer’s investment, whether public or private, is not clearly defined.

Blue carbon is also not currently included among the authorized uses and activities in the concessions for these public lands, which creates a barrier to its development from the outset. Adding to this problem is the fact that the various uses in the DPMT require the payment of a fee , a tax based on the activity carried out and the area occupied.

Blue carbon is still not regulated or quantified as a use, creating uncertainty for developers, who are unaware of the annual cost of implementing this type of project. This cost could range from complete exemption from paying the fee to tens of thousands of euros annually.

Many uncertainties and some certainties

In addition to administrative and regulatory barriers, there are still numerous scientific uncertainties. These are mainly due to a lack of data and a lack of knowledge about the behavior of certain key processes for long-term carbon sequestration in restored marine ecosystems .

Both carbon capture and greenhouse gas (GHG) emission reduction must be quantified rigorously, ensuring the permanence of the sequestered carbon throughout the project’s lifespan.

Among other examples, the high spatial and temporal variability in the fluxes of other potent GHGs such as methane (CH₄) and nitrous oxide (N₂O) and their response after the implementation of these projects is still unclear. If these fluxes were to increase due to the degradation of accumulating organic carbon, the climate benefits of these projects could be reduced .

On the other hand, there are little-explored carbon reservoirs, such as refractory dissolved organic carbon , which, despite its relevance as a long-term element sequestrant, still lacks sufficient research to support its behavior as the restoration process progresses in the project area.

The sea: a costly ecosystem

Another major obstacle is economic. The marine environment is a hostile environment for technical activities and data collection. Projects in these areas often have significantly higher costs due to the need for specialized machinery and highly qualified personnel. The same is true for the data collection campaigns required for carbon capture certification, which are considerably more expensive than those required for green carbon projects .

Blue carbon offset projects have a long term—more than 50 years—and the developer can only obtain credits for captures certified and verified in each verification cycle. Under the Andalusian standard, this is every 7-8 years, which represents a significant financial burden added to the initial implementation costs and project maintenance throughout that period.

Reducing these costs, increasing the reliability of the data obtained, and improving the robustness of scientific assumptions will depend on generating more data, both through funding for basic research in these emerging areas and through measuring real-world data as new projects are launched. Likewise, greater coordination between administrations is necessary, as well as legislative agility to adapt or create regulations in accordance with the new needs and challenges posed by these types of initiatives.

The development of blue carbon sequestration projects in ecosystems represents a great opportunity for environmental and economic improvement for society. One that goes beyond the fight against climate change: it is a strategic opportunity that we must seize. Let us work together to make this new “gold mine” of climate mitigation a reality.

Author Bio: Fernando G. Brun Murillo is Professor of Ecology at the University of Cádiz