Ozone Layer Repair May Have a Surprising Side Effect: A Hotter Earth

The Earth’s temperature is now projected to rise faster than scientists previously anticipated — and one surprising factor behind this trend lies in the future behavior of ozone. While ozone plays a vital role in shielding life from harmful ultraviolet (UV) radiation, it is also a potent greenhouse gas, capable of trapping heat in the atmosphere.

Following the global ban on ozone-depleting chemicals like chlorofluorocarbons (CFCs), the protective ozone layer has been steadily recovering. However, researchers caution that when this rebound combines with worsening air pollution, the resulting warming effect could be up to 40% greater than earlier estimates.

A study led by the University of Reading revealed that between 2015 and 2050, ozone will trap an additional 0.27 watts of energy per square meter (W/m²) of the Earth’s surface — a measure of extra heat retained in the atmosphere. By the middle of this century, ozone is expected to become the second-largest driver of warming, trailing only carbon dioxide, which adds around 1.75 W/m².

Professor Bill Collins, who headed the study, explained:

Published on August 21 in the journal Atmospheric Chemistry and Physics, the study used advanced computer modeling to simulate mid-century atmospheric conditions. The model assumed low enforcement of air pollution controls but strict compliance with the 1987 Montreal Protocol, which phased out CFCs and HCFCs.

The results indicate that while eliminating CFCs and HCFCs was primarily aimed at protecting the ozone layer, the climate benefits are smaller than once calculated. These chemicals are themselves powerful greenhouse gases, so their removal was expected to aid climate efforts. Yet, as the ozone layer heals, its warming influence will offset much of the climatic gain achieved by removing them.

Although reducing air pollution can help limit the formation of near-surface ozone, the recovery of the ozone layer — and the warming it brings — is inevitable over the coming decades, regardless of air quality policy changes.

Ultimately, protecting the ozone layer remains essential for safeguarding human health and preventing skin cancer, as it shields the planet from dangerous UV rays. But this research makes it clear: climate policy must evolve to factor in the unexpectedly strong warming effect of ozone in the years ahead.