The ozone layer that protects human and animal health from the sun’s harmful ultraviolet (UV) radiation continues to be on track for recovery in the coming decades, according to the World Meteorological Organization (WMO) in its latest report released this week.

In 2024, the ozone hole was smaller when compared to the previous years. This was partly due to the natural year-on-year fluctuations and partly due to the success of policies put into place to aid the recovery of the ozone layer.

“Forty years ago, nations came together to take the first step in protecting the ozone layer — guided by science, united in action,” said United Nations Secretary-General António Guterres. “The Vienna Convention and its Montreal Protocol became a landmark of multilateral success. Today, the ozone layer is healing. This achievement reminds us that when nations heed the warnings of science, progress is possible,” he said.

In another report also released this week, WMO, the UN agency that monitors atmospheric science, found that the world’s water cycle is growing more erratic, oscillating from extremes of drought to deluge.

In 2024, only about one-third of the global river basins had “normal” conditions, WMO’s State of Global Water Resources report found. The rest were either above or below normal for the sixth consecutive year.

Mixed bag for human health

Taken together, the two reports present a mix of cheerful and grim news for the planet.

A reduction in the size of ozone hole significantly reduces the risks of skin cancer, cataracts, and ecosystem damage due to excessive UV exposure.

But 2024 was also the third straight year with widespread glacier loss. Many mountain communities depend on glaciers directly for sustenance while rivers originating from glaciers support billions downstream. All of these communities and their livelihoods stand to be affected if this continues and intensifies.

Severe drought gripped the Amazon basin, other parts of South America and southern Africa in 2024. Central, western and eastern Africa, parts of Asia and Central Europe were wetter than normal, WMO’s water report said. Both extremes of drought and floods affect human health.

An estimated 3.6 billion people face inadequate access to water for at least a month per year, and this is expected to increase to more than five billion by 2050, WMO said, quoting data from UN Water, which coordinates UN’s water efforts.

“Water sustains our societies, powers our economies and anchors our ecosystems. And yet the world’s water resources are under growing pressure and – at the same time – more extreme water-related hazards are having an increasing impact on lives and livelihoods,” WMO Secretary-General Celeste Saulo said.

The silver lining – ozone layer recovery in 2024

When compared to the previous years, the total stratospheric ozone cover was higher over much of the globe in 2024, according to the WMO.

The Antarctic ozone hole, which appears over the Antarctic in the South Pole every spring, was below the 1990–2020 average, with a maximum ozone mass deficit (OMD) of 46.1 million tonnes on 29 September (2024). This made the hole smaller than the relatively large holes between 2020 and 2023.

The onset of this hole was also relatively slow in 2024. Scientists observed a delayed ozone depletion through September that was followed by a relatively rapid recovery after the maximum deficit was reached.

“This persistent later onset has been identified as a robust indication of initial recovery of the Antarctic ozone hole,” WMO’s report said.

Ozone recovery – a policy success

WMO’s report on the ozone layer comes as the world marks the 40th anniversary of the Vienna Convention (1985), which first recognized ozone depletion as a global problem, and provided the framework for global action.

Two years after that Montreal Convention (1987) called for the global phase out of ozone-depleting substances like chlorofluorocarbons or CFCs used in refrigerators, air conditioners and even hair sprays.

The protocol has been wildly successful and has led to the phase-out of over 99% of the production and consumption of controlled ozone-depleting substances.

“WMO’s scientific research into the ozone layer dates back decades. It is underpinned by trust, international collaboration and commitment to free data exchange – all cornerstones of the world’s most successful environmental agreement,” WMO Secretary-General Celeste Saulo said.

WMO flags the need for monitoring, long-term action

A key message from the scientists following both reports is the need to invest in science and continue supporting evidence-backed policies.

“Despite the great success of the Montreal Protocol in the intervening decades, this work is not yet finished, and there remains an essential need for the world to continue careful systematic monitoring of both stratospheric ozone and of ozone-depleting substances and their replacements,” said Matt Tully, Chair of WMO’s Scientific Advisory Group on Ozone and Solar UV Radiation.

WMO experts said they hoped countries would take a similar approach to managing their water resources.

“Reliable, science-based information is more important than ever before because we cannot manage what we do not measure.  The WMO’s State of Global Water Resources Report 2024 is part of WMO’s commitment to provide that knowledge,” she said.

Image Credits: WMO.