Finding the forests for the trees: Combating climate change through biodiversity conservation

Trees have symbolized life, strength, and connection across cultures and millennia. Recently, these silent sentinels have garnered recognition as heroes in the fight against climate change.

Carbon storage, combined with reductions in fossil fuel use, is a critical component of achieving net-zero greenhouse gas emissions. Trees offer an accessible, relatively inexpensive solution. Through photosynthesis, trees absorb carbon dioxide from the atmosphere and store it in their leaves, branches, trunks, roots, and surrounding soil. However, planting more trees is not a universal remedy to climate change and may exacerbate the simultaneous crisis of biodiversity loss.

Previously, climate change and biodiversity loss largely have been addressed separately. Now more than ever, experts are urging coordinated action to address these interconnected crises.

Climate change imperils biodiversity by altering habitats through shifting temperature and precipitation patterns. Rising temperatures, increasingly variable precipitation, and more intense and frequent extreme events such as droughts, floods, and fires result in habitat loss. These stressors compound with other major threats to biodiversity, including land-use change, habitat fragmentation, non-native invasive species, pollution, and overharvesting. Collectively, these risks have caused rapid declines in species around the globe. Extinction now threatens over 46,300 species, including 38% of trees and 26% of mammals.

Meanwhile, biodiversity is essential for effective climate adaptation and mitigation. Diverse forests store up to 70% more carbon than monocultures. When an ecosystem has several different species, resources can be used in different ways, reducing competition. This enhanced coexistence promotes plant growth, resulting in higher rates of photosynthesis and atmospheric carbon dioxide uptake. Also, greater biodiversity increases the resiliency of ecosystems, enabling them to adapt to disturbances caused by climate change and other stressors.

“Actions prioritizing both climate change mitigation and biodiversity conservation are more effective at safeguarding the health of ecosystems and the life dependent on them.”

The linked relationship between climate change and biodiversity loss highlights a self-reinforcing feedback loop that can exacerbate the consequences of both crises. More climate change leads to more biodiversity loss, resulting in less carbon storage, more atmospheric carbon, and more climate change.

While measures to conserve biodiversity generally support climate mitigation, the opposite isn’t always the case. Carbon capture strategies such as tree planting may help or harm biodiversity depending on the consideration of broader ecological contexts.

A recent study evaluated the biodiversity impacts of three climate mitigation strategies: reforestation (restoring previously forested areas), afforestation (planting trees in historically unforested areas such as grasslands and savannahs), and bioenergy cropping (farming plants for renewable energy). Reforestation generally benefited vertebrate biodiversity by increasing species’ habitat area while reducing the effects of climate change through enhanced carbon storage. Meanwhile, although afforestation and bioenergy cropping increased carbon capture, these strategies typically led to habitat loss, outweighing the benefits of climate mitigation. These findings highlight that addressing climate change alone is not sufficient to protect biodiversity.

Actions prioritizing both climate change mitigation and biodiversity conservation are more effective at safeguarding the health of ecosystems and the life dependent on them. While reforestation that restores degraded forests to diverse systems is one example, conserving existing forests is also crucial. Mature forests harbor numerous species along with extensive carbon reservoirs in their trees and soils. These forests are home to over 80% of the planet’s terrestrial biodiversity, underscoring the need for their conservation.

The benefits of conserving biodiversity extend far beyond carbon storage and climate change mitigation. People rely on biodiversity for food, shelter, water, and medicines. Diverse ecosystems also provide water and air purification, natural hazard regulation, and disease protection. Nature plays important cultural roles through education, recreation, and spirituality. Protecting biodiversity retains these valuable functions supporting human well-being.

Climate change and biodiversity loss are complex crises. Their close connection means that addressing one issue in isolation will not be enough to avoid detrimental consequences. Conservation and restoration efforts that consider how these risks impact specific social-ecological contexts are essential to protect the Earth and all its inhabitants.