'Another Year, Another New Record': UN Highlights Rising Greenhouse Gas Levels Ahead of COP31

With the next United Nations Climate Change Conference less than two weeks away, a UN agency confirmed Tuesday that levels of three key greenhouse gases in the atmosphere "reached unprecedented highs in 2025, locking in more long-term temperature increase for the planet."

“Another year, another new record," World Meteorological Organization (WMO) Deputy Secretary-General Ko Barrett said in a statement. "The past 11 years have been the warmest on record, and this trend is set to continue."

"The big three are carbon dioxide, methane, and nitrous oxide. Since the 1960s, growth rates of CO2 have tripled," Barrett told journalists during a press briefing about the "Greenhouse Gas Bulletin of 2025," which is published annually.

"When the bulletin was first published in 2004, the annual level of carbon dioxide was 377.5 parts per million. In 2025, it was 426.8 parts per million," Barrett noted. Methane, or CH4, hit 1,948 parts per billion, while nitrous oxide, or N2O, was 339.1 ppb.

"Every additional part per million matters because it traps additional heat," she stressed. "In effect, we are supercharging the ocean and the atmosphere. That means that heatwaves, tropical cyclones, and rainstorms are intensifying faster than our historical baselines prepared us for."

While carbon dioxide is "the most abundant long-lived gas," Barrett also addressed "gases which are present in much lower concentrations but are of potential concern," such as sulfur hexafluoride, or SF6—which "is closely related to electricity production and distribution, and has been rising over the past three decades because of the switch to global electrification."

"Sulfur hexafluoride concentration in 2025 have increased by 249% relative to 1995 levels. They are measured in parts per trillion—not million. So why should we be concerned?" she said. "Because SF6 has an atmospheric lifetime of up to 3,200 years. Its global warming potential is more than 24,000 times that of CO2."

"The energy transition is essential and welcome," Barrett added. "But as with every transition, it has to be done in a smart way and informed by environmental observations."

The WMO bulletin follows a series of recent UN reports showing the Paris Agreement's goal of limiting global temperature rise this century to 1.5°C above preindustrial levels is no longer possible without an overshoot, but getting back to that level is, with ambitious action to phase out fossil fuels.

Additionally, before the ongoing biodiversity summit in Yerevan, Armenia, the UN warned that the world is not on track to meet any of the targets from the Kunming-Montreal Global Biodiversity Framework, or the "Paris Agreement for Nature."

While that event on the global biodiversity crisis—which is linked to the worsening climate emergency—is set to conclude in a few days, world leaders are scheduled to convene again on November 9 in Antalya, Türkiye for the next climate conference, or COP31.

Although the United States is the world's biggest historical climate polluter, and one of the recently released UN reports repeatedly calls out US emissions, Big Oil-backed President Donald Trump has ditched the Paris Agreement, again, and is not expected to send a delegation to Antalya.

"The rest of the world is exhausted when it comes to counting the damage that the US is willingly doing to allies, multilateral structures, economic cooperation, disaster relief," Australian climate scientist Malte Meinshausen told The Associated Press earlier this month. "The rest of the world should probably continue to focus even less on the US."

In the United States, University of Pennsylvania professor Michael Mann said Tuesday that "there is a lot of support among the public for a clean energy transition. The problem is that the fossil fuel industry currently owns our government. But there are reasons for optimism that we might begin to turn the corner, with the midterm elections" on November 3.

"If they return one or both houses of Congress to the Democrats, there will be the possibility of Congress acting as a check on the destructive policies of the Trump administration and in a couple of years, with new leadership at the presidential level, the US could once again reassert leadership on climate," the climatologist told writer Brian McHugh.

"We have to transition rapidly away from fossil fuel burning," Mann emphasized. "There's simply no other way. Without regulating them and imposing an incentive structure that leads them to move toward clean energy, nothing else is really going to matter."