Nature-based solutions for net zero

Volume 2

This issue of FLUXES addresses the potential and limitations of nature-based solutions for carbon ­removals from a scientific perspective:

What can be measured?
What conclusions can be drawn?
What solutions seem adequate?

The observational data produced by ICOS can support policy-makers in various ways. Robust data can help to identify whether and how strong a carbon sink is. Long-term and consistent data can produce reliable estimates of the sizes of the carbon pools and inform how these pools respond to environmental and management changes as the world transitions towards carbon neutrality.

Nature-based carbon sinks have a dual role in climate action

by Katri Ahlgren, Werner Kutsch, Sindu Raj Parampil
Nature-base carbon dioxide removal solutions, sinks, coastal ecosystems, forest carbon farming
Key messages
► EU Climate Law (2021) establishes a framework for the irreversible and gradual reduction of anthropogenic greenhouse gas emissions by sources and enhancement of removals by sinks regulated in Union law.

► LULUCF Regulation (2023) sets out rules concerning commitments of Member States for the land use, land use change and forestry (‘LULUCF’) sector that contributes to achieving the objectives of the Paris Agreement and meeting the greenhouse gas emission reduction target of the Union for the period from 2021 to 2030 and accounting for greenhouse gas emissions and removals from the LULUCF sector and checking the compliance of Member States with these commitments.

► EU Forest Strategy 2030 (2021) sets out to improve the quality and quantity of Europe’s forests and strengthen their protection, restoration and resilience. The strategy also includes re- and afforestation, and focuses on monitoring, reporting and data collection, as well as improving our knowledge of forests through research and innovation. The Forest Strategy is part of the actions listed in the Biodiversity Strategy.

► EU Biodiversity Strategy 2030 (2021) and the related Nature Restoration Law currently under discussion, “aims to put biodiversity on the path to recovery by 2030.” The actions relate to increasing the network of protected areas in the EU, restoring degraded ecosystems both on land and in the seas and unlocking new funding, as well as actions aimed at adopting the new global biodiversity framework. The law stresses the importance of protecting and restoring forests, as well as agricultural, marine and riverine ecosystems for the environmental benefits and services they provide and for their positive socio-economic impacts.

► EU Soil Strategy (2021) and the related new Soil Health Law (2023-2024) being prepared, target to improve the condition of European soils. The law will specify the conditions for healthy soil, determine options for monitoring, and lay out rules conducive to sustainable soil use and restoration.

► EU Common Agriculture Policy 2023-2027 (CAP) entered into force in January 2023. It aims to support farmers and improve agricultural productivity, ensuring a stable supply of affordable food and a living for farmers, while maintaining rural areas and landscapes across the EU. The new CAP also aims to make a significant contribution to the ambitions of the Green Deal, Farm to Fork Strategy, and Biodiversity Strategy.

► EU Farm to Fork Strategy (2020) aims at accelerating the transition to a sustainable food system that helps to mitigate climate change and adapt to its impacts, as well as reverse the loss of biodiversity. It also seeks to ensure food security and everyone’s access to sufficient, safe, nutritious, sustainable food at an affordable price, while generating fairer economic returns.

► Carbon Removal Certification Regulation (2023 or 2024) is being discussed in the European Parliament and by the EU Council in 2023. According to the proposed criteria, the carbon removals need to be quantifiable, additional, long-term and sustainable, and they need to be verified by an external independent verification body. The regulation covers both industrial techniques and natural carbon removal solutions.

Carbon emissions and sinks vary between the years

By Alex Vermeulen, Werner Kutsch, Sindu Raj Parampil
CO₂ fluxes, biogenic fluxes, land ecosystems, ocean fluxes, human emissions
Key messages
► The maps in this article present the three major CO₂ fluxes for Europe and nearby ocean areas, and their variation from 2018 to 2022: biogenic fluxes of land ecosystems, ocean fluxes, and human emissions from fossil fuels.

► Series of maps 1: Net carbon dioxide uptake in the land ecosystems

► Series of maps 2: Net carbon dioxide uptake in the ocean

► Series of maps 3: Carbon dioxide emissions from human activity

Forest carbon sinks under pressure

by Maria Luhtaniemi
forests, carbon sinks, clear-cutting, droughts, forest fires, old forests, biodiversity
Key messages
► The EU's total forest carbon sink decreased by nearly a third between 2010 and 2020. This decrease is attributed to increased harvests and natural ageing of the forests.

► Climate change creates new threats for forests. Fires, droughts, insects and other disturbances diminish the forests’ ability to take up and store carbon.

► Clear-cutting turns a forest into a carbon source. It can take up to 15 years until the forest becomes a sink again, and 20-40 years until initial emissions are compensated for.

► Old forests are vital for carbon storage and biodiversity. The last remaining old forests in the EU should be protected immediately.

► Forest carbon sinks should not be used as an excuse for watering down ambitions of emission reductions. Reducing the use of fossil fuels is still by far the most impactful action to mitigate against the climate crisis.

Coastal ecosystems, reservoirs of life

by Laurent Chmiel
blue carbon, coastal ecosystems, water quality, carbon sequestration, salt marshes, seagrass meadows, seaweed beds, mangroves
Key messages
► Coastal ecosystems provide significant benefits such as contributing to biodiversity, improving water quality, providing resources for coastal communities, consolidating shorelines and sequestering carbon from the atmosphere.

► It is estimated that Europe has lost 50% of its coastal ecosystems since the 1950s, rising to 80% in some regions. Climate change is accelerating this loss.

► Coastal ecosystems degraded by eutrophication or other human activities have been shown to emit more carbon dioxide (CO₂) and methane (CH₄) than healthier ones.

► Losing more coastal ecosystems would have an enormous financial cost: the cost of shoreline erosion in Europe was estimated in 2004 to be one billion euros per year. When accounting for biodiversity loss, decreased water quality and degraded coasts as well, the cost would increase by several billion annually.

► More measurements are needed to fully understand how coastal ecosystems sequester carbon, at what rate, and under which conditions. We also need to quantify the amount of greenhouse gases coastal ecosystems emit.

► Blue carbon studies need long-term monitoring and standardised measurements which are currently unavailable. Existing ICOS ocean data is valuable in supporting these studies, but new and dedicated blue carbon sites are needed. ICOS and two other ocean research infrastructures, JERICO and EMSO, need to work together to bring about this change.

► It is urgent to act now: we must save existing ecosystems by removing the pressures threatening them, efficiently conserving protected areas and restoring degraded ecosystems.

► Although coastal ecosystems sequester carbon dioxide from the atmosphere, they cannot offset the quantities of CO₂ we emit. Coastal ecosystems are not a magic solution to the climate crisis: we must reduce our emissions.

Carbon farming - a path to more sustainable agriculture

by Katri Ahlgren
Carbon farming, soil health, agriculture, croplands, grasslands, LULUCF, agricultural emissions, farming, soil carbon stocks, biodiversity
Key messages
► Major agricultural emissions are methane from livestock and manure management, and nitrous oxide and carbon dioxide from the soils and their fertilisation. These are considered hard-to-abate-emissions when agricultural management and consumer needs remain static. The emissions need to be compensated by sinks in the path to net zero.

► Currently, croplands and grasslands release more carbon dioxide than they take up, according to the European Environmental Agency (2021).

► Carbon farming on croplands or grasslands offers only a very limited capacity for carbon sequestration within soils. It can compensate only a fraction of the agricultural emissions. The results also might not be permanent given the many factors affecting land management decisions.

► Reliably measuring changes in the soil carbon stocks in a given field is difficult, and possible only over long time periods. Carbon farming must be considered from a more general, sustainable farming perspective.

► Besides storing carbon in the ground, benefits include better soil health, improving yields and thus better livelihood for the farmers. More importantly, it improves food security in a changing climate and protects human health, biodiversity, and the environment.

► ICOS uses standardised, high-quality methods to measure carbon exchanges between the vegetation and the atmosphere and the carbon stocks of the soil. ICOS also has a state-of-the-art laboratory for analysing soil and plant samples. The ICOS data and the knowledge of ICOS scientists offer great potential to be utilised when creating a monitoring system for EU Carbon Removal Certification.

The complex chemistry behind the alarming growth in methane

Michel Ramonet, Xin Lin, Philippe Ciais
methane, COVID-19 lockdown, tropical wetlands
Key messages
► The methane cycle in the atmosphere is complex, since it has both natural and human-related sources, and their processes are interlinked.

► The amount of methane in the atmosphere is affected by the amount of other gases like nitrogen oxides (NOₓ), which break down methane.

► During the COVID-19 pandemic, less nitrogen oxide was released into the atmosphere from traffic and industries. As there was less nitrogen oxide to break down methane, more methane remained in the atmosphere.

► Heavy rains in tropical wetlands, due to climate change, increased natural methane emissions during 2021 and 2022.

► Thus two phenomena – less removal and more natural emissions – together caused peaking of growth rate of methane in the two years.