Exactly how much CO₂ is the 10:10 movement saving? This is a question we get asked quite regularly, so we recently decided to have a go at coming up with an approximate answer.

A few hours and lots of number-crunching later and we concluded – much to our satisfaction – that at least half a million tonnes of CO₂ reductions had been committed under the 10:10 banner. That equivalent to taking roughly 200,000 cars off the road.

At least half a million tonnes of CO₂ savings have been committed under the 10:10 banner.

This conservative estimate is based on the data from our emissions reporting tool, which enables businesses, schools and other organisations to calculate and track their emissions and to work out their 10% target.

The data suggests that 10:10 councils are leading the way, with more than 200,000 tonnes of pledged CO₂ savings. 10:10 businesses follow close behind. Next up is central government estate, with a 10% commitment of more than 100,000 tonnes. Add in schools, hospitals, universities, charities and other organisations and the total is far in excess of 500,000 tonnes.

If we were to include the 100,000 individuals who have made a 10% commitment so far the number would go even higher, but without a reliable way to track individuals' emissions data, we couldn't take much more than an educated guess. That should change soon though, with the launch of our all-signing-all-dancing carbon-reduction tool. Watch this space – and in the meantime, thanks to all 10:10ers who have helped us reach this milestone. Next step a million tonnes …