United Nations Secretary General Antonio Guterres is calling on countries to stop new coal plant construction by 2020, accelerate the shutdown of existing facilities, and “tax carbon, not people” in order to avert the “total disaster” that will occur if climate change is not brought under control.

“Stop building new coal plants by 2020,” Guterres tweeted last week. “We need a green economy, not a grey economy.”

On a trip through the Pacific islands last week, he acknowledged the region is “on the front line of climate change” and its people are “important allies in the fight against it,” The Guardian reports.

“Here in the Pacific, sea level rise in some countries is four times greater than the global average and is an existential threat to some island states,” Guterres said. “My messages to governments around the world from the Pacific are clear: first, shift taxes from salaries to carbon. Tax pollution, not people. Second, stop subsidizing fossil fuels. Taxpayer money should not be used to boost hurricanes, spread drought and heat waves, melt glaciers, and bleach corals. Third, stop building new coal plants by 2020.”

Pacific Islands Forum leaders “told Guterres they were ‘running out of time’ and asked him to share a message of urgency with the world, saying they were facing ‘an unprecedented global catastrophe’,” The Guardian adds.

“The blue Pacific—our great ocean continent, our thousands of islands, our strong and resilient people—is running out of time,” the leaders said in a joint statement. “All countries, with no caveats, must agree to take decisive and transformative action to reduce global emissions,” because “if we do not, we will lose. We will lose our homes, our ways of life, our well-being, and our livelihoods. We know this because we are experiencing loss already.”

Guterres highlighted the impacts of climate change on women, stressing that “there can be no successful response to a changing climate without also changing mindsets about the role of women in prevention and response”. He also stressed the role of Pacific voices in shaping the global climate agenda.

“What I was particularly struck by was that he was at pains to flag very clearly that not only are Pacific countries on the front lines when it comes to being victims of climate change impacts, but more importantly they’re on the front line when it comes to resilience and innovation and global leadership,” said Pacific analyst Dr. Tess Newton Cain, a visiting fellow at Australian National University.

“These are small countries that have really not allowed themselves to be seen as hapless victims,” she added. “They have grasped opportunities to take things forward and lead by example. It’s very pleasing that the UN secretary general has acknowledged that.”

Ahead of his trip to the Pacific, Guterres told Associated Press reporter Seth Borenstein he was optimistic that more of the world’s citizens will demand change as climate impacts worsen.

“That is the paradox,” he said. “Things are getting worse. Temperatures are rising faster than expected. We see the Arctic melting. We see glaciers disappearing. We see corals bleaching. We see biodiversity being dramatically threatened. So things are getting worse and worse. But the political will has been slow. We need to reverse this trend. We need to make people understand that this is not sustainable.”

So “the reason I’m optimistic is that I feel more and more people are convinced of that. And as more and more people are convinced of that, I believe governments will feel the need to increase their political will, which at this present moment is still lagging behind.”