Climate-positive tree cover restoration is crucial to curb local warming: Study

Bhubaneswar: Tree cover restoration causes a change in albedo offset on and off the land. Hence, it is important for decision makers to assess the impact of a surface’s albedo change by making use of radiative forcing (RF) and other measures before taking up a restoration drive, revealed a recent study.

A change in albedo offset mostly changes the fraction of sunlight reflected from the Earth’s surface, thereby causing a change in local temperature. It negates the carbon removal benefits in a given land cover largely inducing global warming in general and local warming in particular.

In regions that are naturally conducive to vegetation, tree cover restoration is a widely accepted strategy to remove carbon from the atmosphere and combat the climate crisis. However, restoration alone would not prove to be a fruitful solution to bring global warming under control unless a proper mapping of the land cover has been carried out beforehand, a panel of researchers opined.

The comprehensive climate impact of reestablishing tree cover surpasses mere carbon sequestration. Due to its usual tendency to absorb more solar radiation compared to other land covers, tree cover can contribute to local and global warming. Changes in albedo in certain regions may partially or completely counterbalance the cooling benefits gained from increased carbon storage in trees.

Attempts were earlier being made to quantify the global climate mitigation potential of restoring tree cover which has not adequately addressed albedo due to lack of precise spatial data.

Global maps extensively collected by these researchers reveal that estimates relying solely on carbon may overestimate the mitigation benefits by up to 81%. Particularly in dryland and boreal environments, the albedo discrepancies are notably pronounced. However, there are regions across all biomes where net-positive climate mitigation effects can be achieved. Furthermore, their analysis showed that on-the-ground initiatives are predominantly situated in these more favorable climate locations, yet the majority still encounter at least a 20% albedo disparity. Therefore, effectively deploying tree cover restoration for maximum climate advantage necessitates proper consideration of albedo alteration.

“Our work shows the need to account for albedo change when restoring tree cover for climate change mitigation. It provides tools to do so in a robust and spatially explicit way,” they said.

“We found that albedo-induced CO₂e ranges from 28 to −469 Mg CO₂e ha⁻¹ (or 8 to −128 Mg Ce ha⁻¹). Negative values indicate climate warming (i.e., a reduction of the net climate benefit) while positive values indicate cooling (i.e., an augmentation of the climate benefit). A median value of −120 Mg CO₂e ha⁻¹ (or −33 Mg Ce ha⁻¹) indicates that restoring tree cover generally causes some degree of albedo-driven warming,” the panel of researchers explained in the journal Nature Communications.

Notably, global maps depicting potential albedo changes offer a glimpse into the description. To comprehensively assess how the restoration of tree cover can function as a climate solution, alterations in albedo need to be integrated with shifts in carbon storage, the scholars suggested.

[Disclaimer: This story is a part of ‘Punascha Pruthibi – One Earth. Unite for It’, an awareness campaign by Sambad Digital.]