Settling my Carbon Bill

In my recent book, Lifetime Carbon Debt, I estimated an individual’s annual and lifetime greenhouse gas emissions, their ‘carbon debt’. I then outlined how to reduce their annual emissions going forward, and the options available to address an individual’s lifetime carbon debt. Armed with this information, I began by reducing my daily and annual emissions, for example, by adopting energy efficiency measures in my home, using public transport whenever possible, and paying attention to my diet.  These efforts have reduced my overall annual carbon footprint to low single figures of tonnes of carbon dioxide equivalent (tCO_2e), making it easier for me to address these going forward.

I also took an initiative to address my lifetime emissions which amounted to several hundred tCO_2e. The options here range from financial investments such as buying shares in renewable companies to supporting nature-based projects. I focused on the latter in the form of woodland afforestation and peatland restoration projects in the UK. The former captures and stores carbon dioxide from the atmosphere as part of the natural photosynthesis process; clearly, the more trees that are planted the greater the amount of carbon sequestered.  Degraded peatland areas on the other hand, emit carbon dioxide into the atmosphere and efforts are underway to restore these areas to help minimise emissions; the benefits here then are avoided carbon dioxide emissions that would otherwise occur. 

There are many afforestation projects delivering large volumes of carbon ‘offsets’ into the market; peatland projects have come to the fore more recently making it the junior partner, but this sector is gathering pace.  However, there are risks associated with these projects which impact the amount of carbon sequestered or avoided; for example, tree survival and growth rates in woodland projects, or the quality of restoration and hydrology management in peatland projects respectively. Established methods are used to estimate the amount of carbon dioxide sequestered or avoided and they are independently verified by the Woodland Carbon Code and Peatland Code.

The timescale for these two nature-based activities differs. Afforestation sequesters carbon dioxide slowly with some trees taking many decades to grow to maturity; the long-term fate of the trees is important with mature forests able to store carbon on a century timescale depending on the species involved. Carbon reductions realised in peatland projects are quicker and more secure for the long term, if the areas are left undisturbed and are well managed. There are also wider biodiversity and habitat benefits from such projects.

My lifetime greenhouse gas emissions totalled 590 tCO_2e. Nature helps to reduce such emissions over the long-term through, for example, forest growth via photosynthesis and absorption in the oceans; the former promotes an existing natural process whereas the latter damages the environment for marine life. What is left in the atmosphere is called the Airborne Fraction (AF) and although the value does vary over time, the average has remained relatively stable for many decades. Using only the AF related to the atmospheric processes for the various greenhouse gases reduces my lifetime carbon debt to 330 tCO_2e.

There are organisations offering nature-based offsets into the voluntary carbon market, both profit-making and non-profit making; some operate in the UK while others also operate in countries around the world. It is fair to say that UK offsets are more expensive than international offsets but also benefit from the most rigorous verification processes.