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About us


This website was launched in 2007 to give unbiased information on climate change, carbon dioxide and other greenhouse gas emissions, and how to become independent of fossil fuels. The calculator is constructed according to the best information available, and will be updated as new information becomes available.

The main authors are Ian Campbell and Margaret Campbell.

Ian Campbell BA, BSc, MD, FRCS, FRCR has worked as a doctor and as a medical statistics consultant. As well as medical qualifications, he has a degree in statistics and a doctorate in the use of statistical methods in cancer research - see
On Twitter: @Ian_Campbell_

Margaret Campbell MB, CHB has also worked as a doctor, and currently volunteers on a number of sustainable food and other environmental projects.

They have no financial interest in this area. They have constructed the website because they care about what is happening to our world, and are concerned about the future of their children and future generations.

Thanks are due to Helen, Debbie, Peter, Carol, Geraldine, Clive, Andrew, Patrick, Ann, Gen and John for feedback on earlier versions of this calculator.


  • one of three recommended by Ethical Consumer Magazine (Nov/Dec 2007 issue) in the "Best Overall Online Calculators" category.
  • one of the calculators recommended by the Newsletter of Women's Environmental Network (Winter 2007 issue)
  • recommended by The Three Tonne Club Handbook (2008)

Contact us

Comments on any aspect of this website are welcome.

We aim to give a fair summary of the evidence, and give unbiased conclusions. If we have omitted important considerations, or not given them due weight, please let us know.



Evidence of the severity of the drought in Kenya - this was marked on the map as a river.

First published Feb 2007
Last updated: 9 Jul 2019