Tree planting not a panacea on climate change

Because trees and forests absorb carbon, tree planting is often touted as a strategy for combating climate change. Governments, industry, non-government organisations and individuals have embraced the notion that planting trees can offset carbon emissions. Trees enhance ecosystem resilience, help mitigate heat and extreme weather impacts, and provide habitat for numerous species. That's why I've planted hundreds of trees and am protecting 50 hectares of woodland at Wombat Ridge Nature Reserve in NSW. But it's crucial to dispel the misconception that planting trees can be a panacea for addressing CO2 emissions.

The sheer volume of global emissions, renders tree planting insufficient in offsetting emissions. A back-of-the-envelope estimate from MIT found that US emissions alone would require 30 million additional hectares of forests each year. Globally, the scale required to counterbalance emissions from all sources worldwide is impractical. And even if it were, there would be major impacts on food security and food prices through the taking up of arable land for afforestation projects.

Tree planting as an emissions reductions strategy also requires the carbon offset industry which has failed to prove itself reliable when it comes to afforestation and avoided deforestation credits. Projects claiming to offset emissions through tree planting have consistently fallen short of their promises, raising serious concerns about integrity and effectiveness. A recent investigation found that forest carbon offsets approved by the world’s leading certifier - and used by big companies like Disney, Shell, Gucci - were not only worthless but likely to be making global heating worse.

Finally, recent scientific analysis shows that climate change is affecting trees' capacity to photosynthesise. In increasingly warmer and drier climates, trees struggle with CO2 sequestration. When stressed, they switch from photosynthesis to photorespiration which releases CO2 back into the atmosphere. Published in Proceedings of the National Academy of Sciences, the study's results mean that as climate change kicks in, the capacity of trees and forests to draw down CO2 from the atmosphere will be diminished. They won't be reliable carbon sinks like they have been.

While tree planting is a valuable tool in response to climate change adaptation, it is essential to recognise its limits as an emissions reduction tool. While there are many good reasons to plant trees, the belief that we can offset emissions from flights or new gas projects through afforestation is a misconception. It hinders the pursuit of what's urgently needed - transition to zero emissions. And emerging scientific evidence about the impacts of climate change on trees adds a concerning layer to the conversation, emphasising the need for urgent direct emissions reductions to avoid the worst of climate change and the collapse of our remaining forests and woodlands as carbon sinks and lungs for Earth.