Montreal Protocol drives ozone recovery amid new satellite reentry concerns

The Montreal Protocol continues to drive the recovery of the ozone layer, with nearly 99 per cent of banned ozone-depleting substances phased out. Projections suggest ozone levels could return to 1980 values by 2040 in most regions, 2045 in the Arctic, and 2066 over Antarctica.

As the Kigali Amendment marks its 10th anniversary, the focus remains on phasing down hydrofluorocarbons (HFCs). This amendment, ratified by over 170 countries, aims to avoid up to 0.5°C of warming by the end of the century by targeting potent greenhouse gases used in cooling equipment.

However, new scientific concerns have emerged regarding satellite reentry. As short-lived satellites vaporize upon reentry into the atmosphere, they release aluminium oxide nanoparticles. Researchers warn these particles could potentially catalyze chlorine chemistry in the stratosphere, which may impact the ongoing ozone recovery process. While the scale of this effect remains unsettled and no satellite-driven reversal has been measured yet, the potential for alumina clusters to interact with existing atmospheric chlorine is a subject of active study.