Climate-warming pollution in atmosphere hit record levels in 2023

Concentrations of atmospheric greenhouse gas emissions hit a new record in 2023 and are locking in rising global temperatures for years to come, the World Meteorological Organization (WMO) warned in its annual report card for policymakers.

The assessment is one in a series of reports that will be released ahead of the UN-led COP29 climate summit that kicks off in Baku, Azerbaijan, in November. Another report from the UN Environment Programme published Oct. 24 said the world is headed toward a temperature rise of 2.6 to 3.1 degrees C by the end of the century unless countries strengthen their commitments under the Paris Agreement on climate change.

The WMO, a leading authority on the Earth's atmosphere, said concentrations of carbon dioxide reached 420 parts per million in 2023, a direct result of "historically large fossil fuel CO2 emissions in the 2010s and 2020s." Methane, a gas with a much higher warming potential than CO2, now accounts for 16% of the warming after rising 265% since pre-industrial days, it said.

"These are more than just statistics," WMO Secretary-General Celeste Saulo said in a statement. "Every part per million and every fraction of a degree temperature increase has a real impact on our lives and our planet."

In recent weeks, extreme weather in the US fueled by climate change has been costing lives, livelihoods and business revenue, as seen with the recent hurricanes in the southeastern United States. Duke Energy Corp. is still working to restore power to hundreds of customers after parts of western North Carolina were devastated by Hurricane Helene in late September.

The record 2023 greenhouse gas levels were also fueled by wildfires and a possible reduction in how forests absorb carbon, the WMO said. Extreme heat stresses plants and reduces their carbon uptake.

The WMO scientists pointed to what could be a growing problem of climate change "feedbacks," a situation where collapsing ecosystems begin to trigger even more rapid temperature increases.

"Wildfires could release more CO2 into the atmosphere and the warmer oceans could absorb less CO2," the report said. "As a consequence, more CO2 could stay in the atmosphere, accelerating global warming and ocean acidification. These climate feedbacks are critical concerns to societies worldwide."

In the US, the power sector continues to reduce its carbon footprint, albeit not sufficiently, while emissions are rising in the country's large oil and natural gas industries, recent data from the US Environmental Protection Agency showed. The transportation sector remains the country's largest source of climate-warming pollution.