Greenhouse gases reach new record in 2023: UN October 29, 2024

Rural photo with manicured lawns and lots of gas pollution on the horizon.

By AFP - Agence France Presse

Greenhouse gases reach new record in 2023: UN

By Robin MILLARD

Concentrations of greenhouse gases in the atmosphere hit new record highs in 2023, maintaining future temperature rises for many years, the United Nations warned on Monday.

Levels of the three main greenhouse gases - carbon dioxide, methane, and nitrous oxide, which warm the climate - rose once again last year, the UN's weather and climate agency said.

The World Meteorological Organization said that carbon dioxide was accumulating in the atmosphere faster than ever, increasing by more than 10% in two decades.

The WMO's annual Greenhouse Gas Bulletin comes ahead of the UN's COP29 climate summit, November 11-22 in Baku.

“Another year. Another record. This should set alarm bells ringing among decision-makers,” said WMO chief Celeste Saulo in a statement.

“We are clearly off track to meet the Paris Agreement target.”

Under the 2015 Paris Agreement, countries agreed to limit global warming to “well below” two degrees Celsius above average levels measured between 1850 and 1900 - and 1.5C if possible.

As long as emissions continue, greenhouse gases will continue to accumulate in the atmosphere, increasing global temperatures, the WMO said.

Last year, global temperatures on land and sea were “the highest in records dating back to 1850”, it said.

Given the length of time CO2 remains in the atmosphere, current temperature levels will continue for decades, even if emissions rapidly decrease to zero.

In 2023, CO2 concentrations were at 420 parts per million (ppm), methane at 1,934 parts per billion, and nitrous oxide at 336 parts per billion.

This represents increases of 151%, 265%, and 125% compared to pre-industrial levels before 1750.

“These are more than just statistics. Every part per million and every fraction of a degree increase in temperature has a real impact on our lives and our planet,” said Saulo.

CO2 is responsible for around 64% of the climate's warming effect.

Its annual increase of 2.3 ppm marked the 12th consecutive year with an increase of more than two ppm, a series caused by “historically large CO2 emissions from fossil fuels in the 2010s and 2020s”, according to the report.

Last year's figure is 11.4% higher than the 337.1 ppm recorded in 2004.

“CO2 is accumulating in the atmosphere faster than at any other time in human existence,” said the report, adding that the current level of atmospheric CO2 is 51% above the level of the pre-industrial era.

The last time the Earth experienced a comparable concentration of CO2 was three to five million years ago when the temperature was 2 to 3°C warmer, and the sea level was 10 to 20 meters higher than now, the report said.

Just under half of CO2 emissions remain in the atmosphere, while the rest is absorbed by the ocean and terrestrial ecosystems.

But now “we are facing a possible vicious cycle,” warned Ko Barret, deputy director of the WMO.

Climate change itself could soon “cause ecosystems to become bigger sources of greenhouse gases,” she said.

“Forest fires could release more carbon emissions into the atmosphere, while the warmer ocean could absorb less CO2. Consequently, more CO2 could remain in the atmosphere to accelerate global warming.

“These climate feedbacks are critical concerns for human society.”

rjm/nl