One billion tree plan flawed, says climate scientist

Planting billions of trees to mop up CO2 is ultimately a sensible idea, says Dr. Jim Salinger, but it has to be done in the right way.

He points to recent research showing that regenerating natural forests is far more effective for carbon storage compared to plantation forests of trees like pine. This distinction is crucial for understanding how tree planting can genuinely contribute to mitigating climate change.

The Potential of Tree Planting

Research has shown that planting billions of trees worldwide could be one of the most effective and cheapest ways to remove carbon dioxide from the atmosphere. A study led by Prof. Tom Crowther at ETH Zürich found that a global tree planting programme could potentially remove nearly one-third of all the emissions from human activities that remain in the atmosphere today. The analysis identified 1.7 billion hectares of treeless land suitable for planting 1.2 trillion native tree saplings, an area equivalent to the size of the US and China combined[1].

Crowther emphasized that while tree planting is a powerful climate change solution, it is not a substitute for reducing greenhouse gas emissions from fossil fuels and deforestation. The full effect of removing 200 billion tonnes of carbon through tree planting would take 50-100 years to materialize. Despite this, tree planting is a readily available solution that individuals and governments can implement immediately[1].

The Importance of Native Forests

Dr. Salinger highlights the importance of planting native trees rather than exotic species like pine. Native forests store significantly more carbon over their lifetimes compared to plantation forests. The carbon storage ratio between natural forests and pine plantations is about 40:1, meaning that natural forests are far more effective at sequestering carbon[2]. This is because pine trees are typically harvested after a few decades, releasing the stored carbon back into the atmosphere when they are processed into products like pulp and paper.

Furthermore, pine forests absorb hydroxyl radicals, which can prolong the atmospheric lifetime of methane, a potent greenhouse gas. This side effect complicates the role of pine plantations in climate mitigation[2].

Challenges and Considerations

While the potential of tree planting is significant, there are several challenges and considerations to address. One major issue is the availability of land for planting trees. The study by ETH Zürich specifically excluded crop fields and urban areas, focusing instead on treeless land that could support new forests without disrupting existing land uses[1]. However, much of this land is used for grazing, and integrating trees into these landscapes requires careful planning to ensure it benefits both the environment and agricultural activities.

Another challenge is the species of trees planted. Research indicates that trees thriving in high CO2 environments often have shorter lifespans, which reduces their long-term carbon storage potential. For instance, NASA research has shown that increased CO2 levels have led to significant greening, equivalent to planting a forest twice the size of the continental United States. However, these fast-growing trees die sooner, limiting their effectiveness in sequestering carbon[3].

The Role of Reforestation and Preservation

Reforestation and the preservation of existing forests are critical components of any strategy to reduce atmospheric CO2 levels. Planting new trees is important, but protecting existing forests can be even more effective. Trees in mature forests have already sequestered significant amounts of carbon, and preventing their destruction ensures that this carbon remains stored[5].

Dr. Salinger and other experts argue that a balanced approach is needed. This includes planting native trees, preserving existing forests, and integrating tree planting into broader land management practices. Governments must incorporate tree restoration into their national strategies and support initiatives that promote both reforestation and forest preservation[1][4].

Practical Steps for Individuals and Communities

Individuals and communities can also play a role in reducing CO2 levels through tree planting and other actions. Here are some practical steps:

1. Reforestation: If you own land, plant native trees. This not only helps sequester carbon but also supports local biodiversity.
2. Renewable Energy: Adopt renewable energy solutions like solar panels or participate in carbon offset programs offered by utility companies.
3. Community Projects: Get involved in local reforestation projects and climate action groups to make a collective impact.
4. Waste to Energy Initiatives: Support programs that convert organic waste into energy, reducing overall carbon emissions.
5. Sustainable Transport: Opt for electric vehicles and public transportation to reduce your carbon footprint[3].

Conclusion

Planting billions of trees is a sensible and necessary strategy to combat climate change, but it must be done correctly. Dr. Jim Salinger’s emphasis on regenerating natural forests highlights the importance of choosing the right species and managing forests sustainably. While tree planting alone cannot solve the climate crisis, it is a crucial part of a broader strategy that includes reducing emissions, preserving existing forests, and adopting sustainable practices. By taking a balanced and informed approach, we can harness the full potential of tree planting to help mitigate climate change and protect our planet for future generations.

Citations:
[1] https://www.theguardian.com/environment/2019/jul/04/planting-billions-trees-best-tackle-climate-crisis-scientists-canopy-emissions
[2] https://www.rnz.co.nz/news/national/505066/planting-pine-or-native-forest-for-carbon-capture-isn-t-the-only-choice-nz-can-have-the-best-of-both
[3] https://www.co2meter.com/blogs/news/could-global-co2-levels-be-reduced-by-planting-trees
[4] https://www.rnz.co.nz/news/national/393832/one-billion-tree-plan-flawed-says-climate-scientist
[5] https://climate.mit.edu/ask-mit/how-many-new-trees-would-we-need-offset-our-carbon-emissions