THE EYES THAT WATCH THE SKY

When it launches in 2026, the Copernicus programme's Anthropogenic Carbon Dioxide Monitoring satellite will give us a new window on to Earth's atmosphere... And how we're altering it

- DR STUART CLARK

It's a rather delicious irony that one of the most valuable things to come out of the space programme wasn't the ability to look into the deepest regions of the Universe, but to look back at Earth; to see our world as a beautiful disc of white clouds, blue oceans and multicoloured continents.

Since Sputnik, the first artificial satellite, was launched more than 70 years ago, an armada of Earth-observation spacecraft has been put into orbit. Together with more than a century and a half of consistent Earth-based weather measurements, the data these satellites have gathered has allowed us to develop a much better understanding of our planet's climate and our effects upon it.

As is now well known, Earth's climate is changing, with average global temperatures increasing. This occurs because of the industrial and domestic burning of fossil fuels, which releases carbon dioxide (CO2) into the atmosphere, where it traps heat. We rely on this 'greenhouse effect' to make the planet habitable, but in recent decades so much CO₂ has been released by humans that we've thrown Earth's natural balance off-kilter.

In December 2015, 196 Parties at the UN Climate Change Conference (COP21) in Paris, France, agreed to a legally binding international treaty on climate change. This treaty's goal is to hold global temperatures to below an increase of 2°C. To do this, countries are required to report how much anthropogenic (man-made) CO₂ they emit and, starting this year, they must also report on the actions they're taking to reduce these emissions.

This will allow us to do a global carbon 'stocktake' and, from that, recommend further actions that ́need to be taken on a country-by-country basis. At present, countries calculate their carbon emissions based on statistical and economic factors, such as how much fuel is being imported or produced in the country. The assumption is then that this fuel is used within the country and produces its waste CO2.