Click here if you would like an explanation of how we have done our calculations
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Many of the things we do every day use energy. Generating energy emits greenhouse gases, particularly carbon dioxide (CO2). The Government produces tables that show how much CO2 is given off by different activities. When you enter details of your energy-consuming activities, the calculator uses the official figures to work out how much CO2 is given off.
Example Generating one unit of electricity in the UK emits 0.5266kg of CO2. So using 100 units of electricity is responsible for 100 x 0.5266kg = 52.66kg of CO2 emissions.
We base our calculations on the data used by the UK Government's carbon calculator. You
can download details from
www.defra.gov.uk/environment/climatechange/uk/individual/pdf/actonCO2-calc-methodology.pdf
In turn this refers to 2008 Guidelines to Defra's GHG Conversion Factors: Methodology Paper for Transport Emission Factors, Defra, July 2008; available at: www.defra.gov.uk/environment/business/envrp/pdf/passenger-transport.pdf
Other information comes from the Code of Best Practice for Carbon Offset Providers published annually by
the UK Government's Dept of Energy & Climate Change (previously Dept for Environment, Food and Rural Affairs).
This comes in two parts which can be downloaded from
www.defra.gov.uk/environment/climatechange/uk/carbonoffset/pdf/carbon-offset-codepractice.pdf
www.defra.gov.uk/environment/climatechange/uk/carbonoffset/pdf/carbon-offset-methodology.pdf
The Government figures are averages. In real life there can be some variation.
Example A diesel super-mini is said to emit 145.5g of CO2 per kilometre for each passenger. In real life you can do better or worse than this depending on the model you choose and how you drive. Even so the averages are very useful for working out the impact we have on the climate, how we can live better on low carbon, and how much to offset.
There are about 5000 usable airports in the world. The calculator has details of most of them using excellent data from Navaid (navaid.com/GPX, used with permission. Thank you, Paul Tomblin). First we use the airports' longitude(λ) and latitude(φ) to calculate the angle(ϑ) subtended by them at the centre of the earth. It is a reasonable approximation to treat the earth as a sphere, so we use the simplified formula cosϑ = sinφ1.sinφ2 + cosφ1.cosφ2.cos(λ2 - λ1). Then we multiply the subtended angle by the radius of the earth to calculate the great circle flight distance. We use 3958.5654km for the radius to give results consistent with other calculators that work using nautical miles. All angles are expressed in radians. Finally as recommended by DEFRA we add 9% to take account of diversions and circling.
The calculator is continuously being improved and developed. We do this systematically and carefully to reduce the risk of introducing errors. Also we have an automatic audit system that regularly asks the calculator a whole load of test questions and checks it gives the right answers. However, we are never satisfied! If you think the calculator is making an error or you can suggest an improvement, please email us on info@climatestewards.net
We use your donations in a very practical way to capture CO2 from the air, strengthen communities that are most at risk from climate change and provide habitat for vulnerable wildlife. We do this by planting new forest in the tropics, eg Ghana.
To calculate how much CO2 our new forest will absorb we use a standard computer model called CO2FIX. This takes account of a wide range of factors such as the species of tree, the local climate, survival rates and ultimate use of timber. We calculate the CO2 that will be captured over the next 50 years — this is a long term investment.
We calculate that £10 is enough to capture each tonne of CO2. We review this figure from time to time. Please note, though forests are vital they are not a quick fix. It is important to avoid emitting CO2 in the first place.
Climate Stewards is committed to projects that have benefits that go beyond just absorbing CO2 emissions. We always involve the local community to ensure that they benefit from the planting. This is good for them and also gains their long–term commitment to give the trees the best chance of survival. When we plant trees we use a wide variety of mostly native species to strengthen local biodiversity.
To ensure we work to the highest standards our projects are designed to gain accreditation by the Climate Community Biodiversity Alliance (CCBA, www.climate-standards.org). We believe this is the most rigorous international standard to ensure benefits for communities and biodiversity as well as the climate. We had our first pre-verification report in 2008 and hope to be accredited by 2010.
Thank you for supporting Climate Stewards. Every contribution helps reduce the impact of climate change on us all.