Centennial Forests: Nature's Guardians Against Global Warming

An experiment with century-old oaks reveals that the longest-living trees not only sequester carbon dioxide efficiently but also enhance this capability as they age.

A silent army, with deep roots and towering branches, is tirelessly combating global warming. The relationship between forests and climate change primarily revolves around trees' capacity to absorb carbon dioxide (CO2), the leading driver of rising global temperatures. A recent experiment conducted by the University of Birmingham involving century-old trees has revealed something extraordinary: as these trees age, their ability to capture carbon improves significantly.

What will you learn in this article?

Forests as allies against climate change

With just 25 years remaining until 2050—the milestone set by 196 countries in the 2015 Paris Agreement to achieve net zero emissions—urgent action is required. Success will hinge on leveraging both technological innovation and nature-based solutions.

This is where trees play a pivotal role, thanks to their ability to absorb CO₂. However, not all trees perform equally. Their efficiency depends on factors such as species, location, water and sunlight availability, local climate, soil nutrients—and crucially, their age. An experiment involving century-old oak trees has demonstrated that, as trees age, they refine and improve their carbon-capturing capabilities.

At a 21-hectare site in Staffordshire, a group of 180-year-old English oaks were exposed to elevated CO₂ levels for seven years. The study found that these trees increased their wood production by 10%, effectively sequestering more carbon dioxide for extended periods. Why does this matter? Wood serves as a long-term reservoir for CO₂, preventing its immediate return to the atmosphere, unlike temporary storage in new leaves or roots.

“These trees increased their wood production by 10%, enabling them to sequester more carbon dioxide over many decades.”

Even after being harvested, trees continue to act as carbon sinks when used to create furniture, buildings, or packaging, as the stored CO₂ remains locked away until the materials are burned._.

However, scientists urge caution. As reported by the SINC agency, the accelerated absorption rates observed in individual trees may not necessarily result in a net increase in CO2 storage at the forest level. When old trees die, the carbon they stored can be released back into the atmosphere as they decompose. Protecting forests is, therefore, one of many critical strategies required to mitigate climate change and curb rising global temperatures.

Forests and climate change: the impact on water, health, and our survival

Over the past decade, terrestrial ecosystems have absorbed approximately 30% of the carbon emissions generated by human activities, such as fossil fuel combustion. While CO₂ absorption is vital, it is far from the only benefit forests provide. They positively influence numerous aspects of life on Earth:

Water regulation: Forests are integral to the water cycle, capturing atmospheric moisture and returning it to the soil, thereby ensuring access to fresh water.
Biodiversity: Forests are home to 60,000 tree species, 80% of amphibian species, 75% of bird species, and 68% of the world’s mammals. The loss of forests means the loss of biodiversity, with far-reaching consequences for food chains, pollination, and ecological balance.
Health and livelihoods: Around 6 billion people, including nearly 70 million Indigenous individuals, depend on forests for their livelihoods. Deforestation, particularly in tropical regions, disrupts local temperatures and precipitation patterns, exacerbating climate change's effects on human health and agricultural productivity.

Current threats

Forests are under immense pressure. Each year, 10 million hectares are lost to deforestation, while wildfires destroy an additional 70 million hectares, according to the United Nations.

As a result, forests release up to one-fifth of global greenhouse gas emissions. This situation is exacerbated by global temperatures: as they rise, forests become increasingly vulnerable to drought, forest fires, pests and disease. As forests disappear, their immense capacity to store carbon is lost, and the carbon dioxide released further exacerbates the greenhouse effect.

What forest-based solutions can help tackle climate change?

In response to these threats, several strategies have been proposed or implemented to harness forests' potential as natural shields against climate change:

Massive reforestation and ecosystem restoration: Planting trees in degraded areas can restore their capacity to store CO2 and support biodiversity.
Protection of primary forests and national parks: Conserving old-growth forests is crucial due to their proven long-term CO2 absorption performance.
Innovative forest management: Advances in technology have revolutionised forest monitoring and management. According to the United Nations Framework Convention on Climate Change, innovative systems have helped reduce forest carbon emissions by 13.7 billion tonnes while enabling transparent reporting.
Green economy initiatives: Strengthening incentives for projects prioritising forest restoration and sustainable resource use can drive significant change.
Community education and empowerment: Equipping communities, particularly Indigenous groups, with tools and knowledge enables effective local forest management and protection.

Forests are invaluable allies in the fight against climate change, particularly when considering recent findings on the exceptional carbon-capturing abilities of long-lived trees. Beyond this, forests contribute significantly to water management, biodiversity preservation, and human well-being. However, they face serious threats that demand urgent and decisive action. It is time to make forests a global priority.

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