Energy demand has plummeted during the Covid-19 crisis and global carbon dioxide emissions are anticipated to be 8% lower this year, compared with 2019. Is this affecting our weather and will it affect the global climate in years to come? Carbon dioxide hangs around in the atmosphere for decades so it takes a long time for the impact to play out. Keith Shine, an atmospheric scientist at the University of Reading, estimates the Covid-19 effect might reduce warming by a measly 0.0025°C in about 20 years time. This is far below anything we can observe. If we were to sustain this 8% reduction over the coming years, Shine calculated, we would avoid about 0.15°C of warming but sadly we would still massively overshoot our Paris agreement target of 1.5°C. “This emphasises the scale of the task we have ahead of us,” said Shine. One way in which the reduced emissions might affect our weather is through associated improvements in air quality. Francis Pope from the University of Birmingham speculates cleaner skies may allow more sunlight through, producing a short-lived warming. Shine cautions though that some pollutants have the opposite effect and figuring out which effect dominates, and whether it has a measurable impact on weather, will be challenging.