U.N. Secretary General António Guterres called Wednesday for a “windfall” tax on profits of fossil fuel companies to help pay for the fight against global warming, decrying them as the “godfathers of climate chaos.”

Guterres took particular aim at the carbon-spewing industry and appealed to media and technology companies to stop taking advertising from its biggest players, as has been done in some places with Big Tobacco.

Guterres’ comments in a bare-knuckled speech timed for World Environment Day came as the European Commission’s climate watching agency reported that last month was the hottest May ever—marking the 12th straight monthly record high.

The European Union’s Copernicus climate change service, a global reference for tracking world temperatures, cited an average surface air temperature of 15.9 C (60.6 F) last month—or 1.52 C higher than the estimated May average before industrial times.

The burning of fossil fuels —oil, gas and coal—is the main contributor to global warming caused by human activity.

Meanwhile, the U.N. weather agency predicted an 80% chance that average global temperatures will surpass the 1.5 Celsius (2.7 Fahrenheit) target set in the landmark Paris climate accord of 2015.

The World Meteorological Organization, or WMO, said that the global mean near-surface temperature for each year from 2024 to 2028 is expected to range between 1.1 and 1.9 degrees Celsius hotter than at the start of the industrial era.

It also estimated that there’s nearly a one-in-two chance—47%—that the average global temperatures over that timeframe could top 1.5 C, an increase from just under a one-in-three chance projected for the 2023-2027 span.

Guterres spoke from the American Museum of Natural History in New York in a bid to revive focus on climate change at a time when many national elections, and conflict in places like Ukraine, Gaza and Sudan this year have seized much of the international spotlight.

He repeated concerns about subsidies paid out in many countries for fossil fuels, which help keep prices low for consumers.

“Climate change is the mother of all stealth taxes paid by everyday people and vulnerable countries and communities,” he said. “Meanwhile, the godfathers of climate chaos — the fossil fuel industry — rake in record profits and feast off trillions in taxpayer-funded subsidies.”

Guterres said that global emissions of carbon dioxide must fall 9% each year to 2030 for the 1.5 C-degree target under the Paris climate accords to be kept alive. But temperatures are “heading in the wrong direction,” he said: They rose 1 degree last year.

“We are playing Russian roulette with the planet. We need an exit ramp off the highway to climate hell,” Guterres said, while adding: “The truth is, we have control of the wheel.”

“This forecast is affirmation that the world has entered a climate where years that are as hot as 2023 should no longer be a surprise,” Noah Diffenbaugh, a professor at Stanford’s Doerr School of Sustainability, said in an email of the WMO forecast.

Guterres called on advanced economies in the Group of 20 countries — which are holding a summit in Brazil next month, and are responsible for about 80% of all emissions — to take the lead. He also said that the richest 1% of people on the planet emit as much as two-thirds of all humanity.

“We cannot accept a future where the rich are protected in air-conditioned bubbles, while the rest of humanity is lashed by lethal weather in unlivable lands,” Guterres said.

He appealed to “global finance,” alluding to banks and international financial institutions, to help contribute money, saying “innovative sources of funds” are needed.

“It’s time to put an effective price on carbon and tax the windfall profits of fossil fuel companies,” he said.

But Guterres said that all countries — and people — must join the fight, including the developing world, such as by ending deforestation and meeting targets to double energy efficiency and triple renewables by 2030.

Some critics say Guterres, which such alarmist speeches, puts too much a focus on stirring emotions than focusing on science that lays out the actual threat.

But U.N. officials and nongovernmental groups acknowledge that the secretary-general has little power beyond the “bully pulpit” — his perch at the head of the world body — to stir people, governments and business to change.