For you weekend warriors, before you go out and purchase “plastic wood” for that next deck project, you may want to think again if your motivation is being more sustainable. An article in this week’s Nature by Jeff Tollefson titled ‘Plastic wood’ is no green guarantee, reveals that carbon emissions from plastic-wood manufacturing are 45-330% higher than redwood production, based on a study by the Consortium for Research on Renewable Industrial Materials, a public-private partnership based at the University of Washington. Another article by Julia Pongratz, Plant a tree, but tend it well, reveals some potential limits of forests as carbon sinks from nutrient constraints.
Both articles got me thinking about society’s push for more paper recycling, substitutes for wood construction materials and home furnishings, and greater efficiencies. Taking a moment to survey my own home, its wood frame and all its furnishings, including a natural wood deck, I see my own personal carbon sink. Although I have no empirical evidence to support my thesis, it strikes me that our good intentions to save forests and repurpose plastic into useful materials – making us less reliant upon forests and woody biomass – may be yielding unintended consequences. What I love about forests is that they are renewable – mother nature’s way of giving back to herself. Additionally, the more forests we grow and use, and replace with new, younger forests, the more carbon we sequester in our daily living. This may be a wild oversimplification, but I think there is something to it. According to a 2009 CSR report on Carbon Sequestration in Forest
Mitigating climate change by enhancing forest carbon sequestration may be a relatively low-cost option and would likely yield other environmental benefits. However, forest carbon sequestration faces challenges: measuring the additional carbon stored (over and above what would occur naturally); monitoring and verifying the results; and preventing leakage. Numerous issues regarding the carbon cycle in forests, monitoring the levels and changes in forest carbon, and the scientific uncertainties about the relationships among forests, carbon, and climate change are likely to be the subject of ongoing federal research efforts, with funding and oversight by the Congress.
But in society’s rush to green itself, we may be missing something equally, if not more important. As a weekend warrior and lover of forests, I have long cherished the aesthetic qualities of wood. There is nothing quite like the beauty and elegance of black walnut, with its rich brown tones, distinct knots and contrasting striations – all reminders of the 200 years of growth, struggling to survive the insults of winter and drought, and the many contributions to wildlife – the many nests its limbs once supported, the hollows it offered up as shelter, and the yearly bounty of food for all the critters scurrying about the forest floor it once graced. Sorry, but plastic wood just doesn’t give me those same feelings or important reminders. While we have much more to learn about the global carbon cycle and the best sustainable choices, in the interim, I will continue to opt for my woody biomass.