Our team of researchers at You Change Earth provides estimates for the impact that users can
have for a select few projects that fit into the ‘Lifestyle Changes’ category. Check out our
guiding criteria for how we choose these projects. Lifestyle actions include projects like Green
Your Diet and Power Your Home Through Clean Energy.
We quantify the impact of each of these projects by evaluating the tasks contained within each one, and tallying up the total carbon sequestered for a median user completing this project. While the realized CO2e savings for each person who takes action on our site will differ based on their location, effort level, and hundreds of other factors, our estimates give users an indication of the general amount of carbon their actions have saved.
For example, here is how we calculate the emissions reduction for our Green Your Diet guide:
1. First we get our data from this Oxford University Study.
2. Then we calculate annual emissions for a number of different diets.
High meat consumption (>100g per day) has associated carbon emissions of 7.19kg per day,
which is 2.62 tonnes of CO2 per year. Other daily and annual carbon footprints for different diets are detailed below:
- Medium meat eaters (50-99g/d) = 5.63kg/d = 2.05 tonnes per year
- Low meat eaters (<50g/d)= 4.67kg/d = 1.70 tonnes per year
- Vegetarian - 3.81kg/d = 1.39 tonnes per year
- Vegans - 2.89kg/d = 1.05 tonnes per year
3. Next we evaluate a few different behavioral changes that users could undertake through
You Change Earth
High meat -> vegan = 1.57 tonnes
Medium meat -> vegetarian = 0.66 tonnes
High meat -> low meat = 0.92 tonnes
Medium meat -> vegan = 1.0 tonnes
4. In this case we settled on a user adjusting their diet from high meat to low meat (~1
tonne) as a fair estimate for carbon saved by the average user undertaking this project.
Of course the fact that a user may influence consumption decisions for others in their household might end up amplifying the effect that a user has far beyond the tonne they reduce, but we are only striving for a fair, and median estimate of the impact that a given user can have. For information on how we calculated emissions from any of our other projects, contact team@youchangeearth.org.
Converting tonnes to other metrics:
Tonnes of CO2 can be an opaque figure that doesn’t convey a lot of meaning for everyone. As
such, we also convert this figure into the number of trees, and dollars that are associated with this
quantity of emissions. This gives our users a more tangible sense of the contributions they are
making.
To convert tonnes to trees:
The EPA estimates that for an average urban tree planted, 0.060 metric tonnes of CO2 are sequestered once tree type and survival probability are accounted for (Source).
Dividing 1 tonne by this 0.060 gives us a value of ~17 trees per tonne of carbon saved.
To convert tonnes to dollars:
We multiply the tonnes a user is committing to saving by the standard for the ‘social cost of carbon’. This number is calculated with models that estimate the total economic damages that we will endure for each additional tonne of CO2 we emit.
The widely accepted value for this (as used by the US government) is ~$50 (Source).
Important note on quantification:
In many ways, the most impactful actions on You Change Earth are those that involve using your time and effort to fight for the climate, and are therefore quite hard to quantify in tonnes of carbon. As a result, we have not tried to come up with figures for these. However, make no mistake that these projects are the core of how You Change Earth contributes toward helping avert this climate crisis because of their ability to affect systematic change to the way our businesses, governments, and societies deal with climate change.
We cannot stress enough how vital they are, even if we are unable to put an exact dollar figure next to them.