Severe wildfires last year added to the already rapid accumulation of planet-heating greenhouse gasses in the atmosphere, highlighting a potential vicious cycle as the average temperature rises, the U.N. weather agency said ahead of the next round of international climate talks.
The amount of carbon dioxide in the atmosphere is comparable to levels of 2-3 million years ago when the average temperature was as much as 3 degrees Celsius, or 3 C, warmer and sea levels 10-20 meters [33-66 feet] higher than now, the World Meteorological Organization said in its annual Greenhouse Gas Bulletin.
It said carbon dioxide from fossil fuels and cement production continues to be emitted at a faster rate than can be absorbed by the ocean and forests. The unabsorbed portion lingers in the atmosphere for centuries, driving the so-called greenhouse effect of a hotter climate.
“These are more than just statistics. Every fraction of a degree of temperature increase matters,” the agency’s deputy secretary general, Ko Barrett, told a press conference in Geneva on Monday.
“It matters in terms of the speed of glacier and ice retreat, the acceleration of sea-level rise, ocean heat and acidification,” she said.
“It matters in terms of the number of people who will be exposed to extreme heat every year, the extinction of species, the impact on our ecosystems and economies.”
The 29th U.N. climate negotiations are due to take place next month. The host, Azerbaijan, is ruled by an authoritarian government with power concentrated under President Ilham Aliyev and his family. Its economy is reliant on oil and gas exports.
At the 2015 climate negotiations, some 195 nations agreed on the desirability of limiting the increase in average temperature versus the preindustrial level to 1.5 C. Many climate scientists warn that continued reliance on fossil fuels means greater heating is already locked in for later this century.
The current level of temperature increase is about 1.2 C. Sea-level has risen about 24 centimeters (9.4 inches) since 1880.
The WMO bulletin said Canada’s worst-ever wildfires and severe bushfires in Australia added to “stubbornly high” carbon dioxide emissions from human and industrial activities in 2023.
There was also a possible decrease in the amount of carbon dioxide absorbed by forests because of the end of a three-year-long La Nina in May 2023 and the onset of the warmer El Nino, which affects weather globally, it said. Plants absorb less carbon at higher temperatures.
Even so, historically large fossil fuel emissions in the past two decades are the main driver of the overall increase in greenhouse gasses, the agency said.
The globally averaged concentration of carbon dioxide reached 420 parts per million in 2023 following the 12th consecutive year of an annual increase of more than 2 parts per million.
Carbon dioxide is “accumulating in the atmosphere faster than at any time during human existence,” the WMO said.
In the near future, the world could witness compounding effects from higher temperatures and the environment itself could become a larger source of greenhouse gasses, the organization warned.
For example, wildfires could release more carbon dioxide and already warmer oceans and landscapes would absorb less of it, meaning more of it stays in the atmosphere and accelerates warming.
“These climate feedbacks are critical concerns to societies worldwide,” the WMO said.
RELATED STORIES
UN climate case could be global circuit breaker: Vanuatu official
Heatwaves 30 times more likely due to climate change, scientists say
EXPLAINED: The impact of climate change on the Tibetan plateau
Edited by Taejun Kang