Researchers develop global dataset to plot areas for land-based carbon storage

To achieve the Paris Agreement's goal of limiting the rise of global temperature to well below 2°C, emissions of carbon to the atmosphere must remain below 250 petagrams from 2021 onward.

Presently, that amount of carbon, in all likelihood, will be emitted by 2045.

Countries should aim for greenhouse gas emissions to reach net-zero by mid-century, and measures should be adopted that limit the increase in global temperatures this century to 35.6 °F (2 °C ) above preindustrial levels.

The need for a consistent, spatial dataset

Now, in recent years, forests have been considered an efficient carbon sink through afforestation, forest management, and reduced deforestation. While several countries have included forest sequestration activities toward reducing net carbon emissions as part of the Paris Agreement, countries like the United States and Europe use wood as a source of biomass energy.

But, forceful cuts in emissions, such as a transition from fossil fuels to renewable energy sources, must go hand in hand with carbon dioxide removal (CDR) or negative emissions strategies.

Though large-scale CDR seems to have 'promising options', increasing carbon storage in forest ecosystems, such as woody biomass, has been widely recognized with high climate mitigation potential, with several environmental and socio-economic co-benefits.

But, previous research does not aid in the targeted implementation of natural climate solutions, as they lack estimates for additional land-based carbon storage or its spatial distribution.

To combat this, Dr. Wayne Walker, an ecologist, and remote sensing specialist, and his colleagues have developed a globally consistent spatial dataset that helps map current, potential, and unrealized areas for land-based carbon sinks. Their study was published in the PNAS. 

Increasing carbon storage while preventing loss due to degradation

According to their research, increasing carbon storage in woody biomass by planting trees or protecting forests can help achieve climate goals by removing CO2 from the atmosphere. 

Their approach doesn't explicitly refer to managing globally important systems toward “forests” as traditionally defined by tree cover, but rather management toward the 'mature' woody carbon density characteristics and associated biodiversity complement of the native ecosystems. 

The difference between current and potential carbon storage globally was calculated at a resolution of 500 meters. After excluding the land used for food production or human habitation, the authors estimated an unrealized potential carbon storage opportunity of 287 petagrams. Among these, more than two-thirds of the available reservoir is held in the tropics, and 78 percent is in biomass such as trees and roots, in comparison to soil.

As per the study, improved management of existing forests could offer three-fourths of the total unrealized potential, with 71 percent concentrated in tropical ecosystems. This could help realize more than half of the available opportunities by increasing storage while preventing loss due to degradation or forest conversion.

'Absolute reference point'

However, climate change is a 'source of considerable uncertainty'. 

While more research is required to fathom the impact of natural disturbances, the authors project that the potential for additional carbon storage in woody biomass will increase by more than 17 percent by 2050. This increase is despite the projected decreases (212 percent) in the tropics. 

The authors state that the high-resolution dataset is an absolute reference point and can help establish priorities for land-based carbon storage.