A sizeable cast of global leaders including Pope Francis, United Nations Secretary-General António Guterres and national heads of state marked World Environment Day today with a round of stark warnings over social media about the risks to people and to health of environmental degradation, air pollution and climate change – topics that will demand more than words at September’s upcoming UN Climate Summit in New York.

Meanwhile, thousands of grassroots events were underway around the world marking the day – celebrated every year on 5 June – organised by students, political leaders and pundits. The activities, ranging from bike rides and eco-runs for clean air in Brazil and Geneva, to beach, river and ocean clean-ups and tree-plantings in Southeast Asia, added up to over 6,200 events worldwide, according to UN Environment, which published a map to track all of the happenings.

If in years past, the focus of World Environment Day was on wildlife, plants and ecosystems, this year’s #BeatAirPollution theme, reflects a growing recognition by environmental groups that people-centred messages focusing on health and well-being may be key to tackling pollution sources such as waste burning and poor waste management, energy inefficiencies, and fossil fuel combustion, which are simultaneously driving rapid climate change and biodiversity loss.

Guterres set the tone with his clarion call to action in a video released yesterday on his Twitter account.

“The quality of the water we drink, the food we eat and the air we breathe all depend on protecting the natural world,” he said.

“But the environment is facing unprecedented perils caused by human activity. One million species are under threat of extinction. Oceans are under stress. Air pollution is claiming 7 million lives a year, and damaging children’s development. Many air pollutants also cause global warming. And climate change is an existential threat. There is no time to lose. This is the battle of our lives.”

“Solutions exist,” he added. “Tax pollution, not people. Stop subsidizing fossil fuels. Stop building new coal plants. People everywhere are demanding action. On World Environment Day, lets heed that call.”

In London, Prime Minister Theresa May, the outgoing Conservative Party Leader, also took time out from a State Visit to the United Kingdom by US President Donald Trump to mark the occasion, saying:

“Our mission is to build a Britain where the next generation can enjoy a better life than the one that went before. That’s why we’re working hard to #BeatAirPollution and proudly support #WorldEnvironmentDay,” tweeted May.

Trump, a climate skeptic who has nonetheless said he supports clean air and water, ignored the date.

But other global leaders were ready to step up to the plate:

India’s Minister of External Affairs, Dr. Subrahmanya Jaishankar, posted a photo of himself planting tree saplings: “Making the world a better place. One tree at a time,” he said in a tweet.

Pope Francis, meanwhile, also tweeted a message with a health theme, saying “Today, with gratitude to God, we remember that our body contains the elements of the planet: its air is that which gives us breath, and its water revives and restores us.”

Meanwhile China, the official host of this year’s official World Environment Day celebrations, was co-sponsoring dozens of activities around the country with UN Environment, the organiser of the annual event.

UN Environment also posted a live feed of events happening there and around the world – ranging from Hangzhou, China aglitter with #Beatairpollution banners to high-level dignitaries donning air pollution masks, and “Love letters to the Air” by third grade students in Brooklyn.

Image Credits: Rachel Chew/WWF, UN Environment, Indian Ministry of External Affairs.