“The clearest way into the universe is through a forest wilderness.” – John Muir

“But what have trees done for us lately?” you ask. 

For starters, trees provide us wood used in the buildings that shelter us and the furniture on which we work and rest. Forests are home to two-thirds of the planet’s land species. They help capture, store and purify water passed on to cities and towns downstream. By some estimates they even supply nearly half of the ingredients found in medicines we rely on to keep us healthy. But more topical this week, as we celebrate Earth Day and Arbor Day and contemplate the state of our planet, forests are effectively the lungs of the Earth. They absorb carbon dioxide from the atmosphere and release the oxygen we need to survive.

If you were paying attention in school you learned that carbon dioxide – the major greenhouse gas driving climate change – is in essence, plant food.

Through the process of photosynthesis, trees absorb sunlight (thanks to the presence of a pigment found in all green plants) and suck up water and carbon dioxide to produce carbohydrates and oxygen.

Photo credit: https://www.pinterest.com/pin/57561701462135038/

Photosynthesis is the most effective means for removing carbon from the atmosphere.

The carbon captured is converted into tree roots, trunks, branches and leaves (collectively, “biomass”). The process absorbs nearly 30 percent of mankind’s annual carbon dioxide emissions (released principally through the combustion of fossil fuels), prompting the curious mind to ask, “is it possible to minimize, if not altogether eliminate, the threat of climate change by planting more trees?”

Here’s the short answer: Planting more trees – in and of itself – will not solve global warming. After all, it’s called the carbon cycle for a reason. Carbon sequestered in biomass must someday return back to the atmosphere, either through natural decay or human interference. Newly planted or regenerating forests can continue to absorb carbon for 50 years or more, however, it is hypothesized that even if tree-planting were executed on a massive scale, the incremental trees would capture only 2 to 3% of total annual global greenhouse gas emissions. Link: http://www.theguardian.com/environment/2012/nov/29/planting-trees-climate-change

Make no mistake, deforestation contributes to global warming.

In fact, it’s the second leading cause. The Union of Concerned Scientists estimates that tropical deforestation (e.g., in the Amazon, the Congo and Indonesia) causes as much as 10% of the world’s heat-trapping emissions to go unabsorbed each year. [source: http://www.ucsusa.org/global_warming/solutions/stop-deforestation/deforestation-global-warming-carbon-emissions.html#.Vxp1i2NZsy5] That’s why it’s important that the trees we do use come only from well-managed forests where sustainable practices are rigorously employed, such as North America’s hardwood forests.

Whereas the Kyoto Protocol encourages tree planting and reforestation, experimental projects to date have identified a number of hurdles, including the high input costs (principally land and labor) and the cost of protecting young trees from natural threats. One other interesting learning is that we must plant the right trees in the right places. Tropical forests benefit the planet by lowering overall temperature, whereas forests far from the equator are more likely to trap heat in their dense canopies, thereby raising temperatures. [source: Lawrence Livermore National Laboratory].

So while planting more trees cannot reverse global warming, you simply can’t go wrong by greening up your neighborhood and your planet, and by buying lumber and finished goods made of wood harvested from woodlands that are managed in a sustainable fashion so they are sure to absorb the maximum amount of carbon possible.