Why the Guardian is putting global CO2 levels in the weather forecast

As CO₂ levels climb, the carbon count is a daily reminder we must tackle climate change now

The simplest measure of how the mass burning of fossil fuels is disrupting the stable climate in which human civilisation developed is the number of carbon dioxide molecules in the atmosphere.

Today, the CO₂ level is the highest it has been for several million years. Back then, temperatures were 3-4C hotter, sea level was 15-20 metres higher and trees grew at the south pole. Worse, billions of tonnes of carbon pollution continues to pour into the air every year and at a rate 10 times faster than for 66m years.