The upper layer above the northern hemisphere is likely to be completely repaired by the 2030s and the entire layer by 2060, says the UN

Just over three decades ago, scientists were sounding alarm bells over the parlous state of the ozone layer. It was suffering severe degradation due to harmful manmade aerosol chemicals being released into the atmosphere. Now, according to the latest assessment of its condition, the layer shows signs of continuing improvement and may recover fully by 2060 – a remarkable turnaround that shows what is possible with global action.

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Widespread concerns about the ozone layer – a mass of gas in the stratosphere that shields Earth from UV rays – were raised in the 1980s. Scientists found it was shrinking due to the prevalence of chlorofluorocarbons (CFCs) and halons. The gases were commonly used in aerosols and refrigerators. The warnings led to the signing in 1987 of the Montreal Protocol, which committed nations to reducing the production of such gases. The most recent assessment of the ozone suggests that its upper layer in the northern hemisphere will make a full recovery by 2030, and in the southern hemisphere by 2060. As well as the clear environmental benefits, the UN estimates that up to 2m cases of skin cancer could be avoided each year as a result.

Damage to the ozone layer above Antarctica could be repaired by 2060. Image, of Elephant Island, by Henrique Setim