How do we get these figures?

We start by breaking each story’s carbon footprint down into two parts: carbon emissions from reporters’ transport for the story, and the emissions from the digital infrastructure needed to publish it.

Transport emissions

When deciding whether to even assign a story, how much travel is required is a key factor for us. If a reporter needs to take a flight to reach their story, we are highly unlikely to commission it. We would encourage them to look for stories closer to home or discuss whether it’s possible to do the story justice with reporting by phone and video calls. Cutting out flights is a major way we’ve reduced the carbon footprint of Future Planet. A single flight from London to, say, Cape Town, for example, emits 1.6 tonnes of carbon – the equivalent of running an average home’s electricity for nearly 100 days.

Once a story has been commissioned, our reporters keep note of what travel they do to report the story, including how far they go and the method of transport they use. To calculate the carbon emissions of this, we use the carbon calculator Albert, a tool developed at the BBC and used by other media organisations. The tool is designed to monitor emissions from television productions.

Of course, Future Planet is a digital feature site and not a TV programme, so we specifically use Albert’s carbon calculator for its travel calculations. This takes into account not only the miles travelled, but the fuel type used and the size of vehicle. You can read more about Albert and the BBC’s sustainable production practices here.

Digital footprint

This part of the calculation involves estimating the energy used to transfer data over the internet and the carbon intensity of electricity (the amount of CO2 emitted per unit of electricity consumed). We worked with the agency Wholegrain Digital to get a bespoke carbon estimate for Future Planet stories. (The BBC does not endorse particular products or services; rather, it was the only agency we could find offering a service to calculate carbon for a website’s emissions.)

For a digital story, one of the big things we need to think about is the number of people who read it. As we can’t predict exactly how many readers will click on the story before we publish it, we use a per-pageview emissions estimate, which is the same for all stories. We got this figure using a test story, calculating emissions as above and then dividing that by the pageviews that the test story actually had over six months. That gives us a better estimate than just plugging in the URL from a story to the agency’s standard carbon calculator, because for a story where the number of pageviews is a weighty factor in the equation, using data on actual pageviews makes it more accurate.

The story we used as a test to get this figure was a BBC Future story, and we used the actual number of pageviews it had over a six-month period. Factors such as how many images a page has and the length of the story can make a big difference in the energy required to load the page, and how long the reader spends on the page. Our stories vary in length and number of images, so it’s important to stress that this figure is an estimate, not a precise measurement.