This is a first in a series of exclusive Green Energy Times articles on some myths about climate change and the role trees and forests play in mitigating climate change’s effects.
We Shouldn’t Cut Trees if We Care about Climate Change – Right? Wrong.
It seems simple and intuitive, right? If we want our forests to help mitigate the effects of climate change, we should just leave them alone to grow. Sometimes simple ideas are correct, but this one is not – in fact it’s dead wrong.
There are important myths surrounding this issue. There are some who believe if we don’t harvest trees, then the forest keeps on growing and sequestering carbon forever. That is not true. Trees and forests, though often longer lived than humans, age as they grow bigger and older and their growth slows down – quite a bit, actually. Their sequestration of carbon also slows down.
And let’s not forget that what this all about is climate change being caused mostly by greenhouse gas emissions from the burning of fossil fuels in electricity power plants, manufacturing facilities, heating buildings and transportation vehicles. Forests only offset some of those emissions here in the U.S. and in the world. The real way to reduce emissions is to slow or stop them at the emitting point – the power plant, factory, building heating unit or car or truck on the road.
There are two important terms to understand if we want to talk about forest carbon and climate change:
Carbon sequestration – the process of removing carbon from the atmosphere through photosynthesis and storing it in another form that cannot immediately be released – wood.
Carbon storage – the total amount of carbon contained in a forest both aboveground (mostly trees) and below ground (mostly soil) at a given time.
Carbon sequestration is about today and the future. What we want from our forests is to offset as much of atmospheric emissions today and into the future – across the landscape. Scale – i.e. landscape – discussion is extremely important because climate change and greenhouse gas emissions are not just about one spot on earth, instead, it is a global issue. The kind of forest across the landscape that sequesters the most carbon is a young to middle aged forest – NOT an old forest.
Rate of Carbon Sequestration in Forests of the Northeast U.S.
Figure 1 shows that forests less than 20 years old sequester the most carbon. Larger negative numbers in the graph show the highest sequestration rates. As the forest ages, the rate of sequestration over the landscape is reduced. So, if we want high carbon sequestration rates today and in the future to offset greenhouse gas emissions causing climate change – we want younger forests.
Carbon storage is the opposite of sequestration when it comes to forest age. As forests grow older and the trees become larger, they store more carbon than younger forests. This carbon storage represents the sequestration that occurred in the past – which we cannot change. We don’t want to release all the forest carbon in these older (or even younger forests), but carbon storage does not address today’s, and future, emissions. Younger, vigorously growing forests are the best across the landscape at removing the most greenhouse gas emissions (carbon) to combat emissions from fossil fuel burning and their effects resulting in climate change.
What about cutting trees? We use wood from trees for so many things in our lives: from our homes, to furniture, to heat our homes and yes, for toilet paper and paper in books. Products from trees are so much more environmentally friendly than from fossil fuel sourced products (think steel and concrete in buildings or plastics) because trees and forests are renewable. In the northeast U.S. they grow back naturally – we don’t have to plant them – because our soils, climate and tree species naturally produce seed or sprouting from stumps to regrow our forests.
Simple thinking says if we don’t cut trees then the planet will be better off because trees sequester carbon. The problem with that thinking is the issue of “leakage” and myth #2. Leakage from a forest carbon perspective is that if you don’t harvest a tree here for products, it will be harvested somewhere else because demand for wood products is increasing in our region, the country and the world (Figure 2). It is naïve to think that if we stop harvesting a tree on a property or in our region that there are only positive climate effects. In the northeast U.S., we have laws and regulations to assure that timber harvesting is done in an environmentally sound manner. If we don’t harvest trees here, they will be harvested elsewhere – and maybe in parts of the world with less resilient forests like the rainforests of South America. This would not be better for the planet.
Harvesting trees sustainably here also can increase growth rates on the remaining trees in the forest where harvesting occurred, resulting in increased carbon sequestration rates – the most important part of forest carbon and climate change.
Global timber consumption for all uses 1960-2020
And by the way, we grow way more trees and carbon in our northeastern forests than we remove each year. We will talk much more about that in the next article.
So, the bottom line is that younger forests sequester more forest carbon per area than older forests and cutting trees here in the northeast, for all the valuable products we need, can be done sustainably in a forest that grows way more than is harvested each year. Not harvesting here just pushes the demand for forest products to other forest harvesting elsewhere and does not result in an improvement in our global climate change situation.
Charles Levesque is President of Innovative Natural Resource Solutions, LLC – a northeastern U.S. based consulting firm. He also serves as Executive Director of the North East State Foresters Association and is Coordinator of the new Securing Northeast Forest Carbon Program.