Levels of the three most important heat-trapping gases in the atmosphere reached new record highs last year, US scientists have confirmed, underscoring the increasing challenge posed by the climate crisis.
The global concentration of carbon dioxide, the most important and common of the greenhouse gases released by human activity, rose to an average of 419 parts per million in the atmosphere in 2023, while methane, a potent but shorter-lived greenhouse gas, rose to ‘ an average of 1922 parts per billion. Levels of nitrogen oxide, the third most significant human-caused warming emitter, climbed slightly to 336 parts per billion.
The increases are not quite in line with the record jumps seen in recent years, according to the National Oceanic and Atmospheric Administration (NOAA)but still represents a major change in the composition of the atmosphere even from just a decade ago.
Through the burning of fossil fuels, animal agriculture and deforestation, the world’s CO2 levels are now more than 50% higher than they were before the era of mass industrialization. Methane, which comes from sources including oil and gas drilling and livestock, has risen even more dramatically in recent years, Noaa said, and now has atmospheric concentrations 160% greater than in pre-industrial times.
Noaa said the march of greenhouse gas levels was due to the continued use of fossil fuels, as well as the impact of wildfires, which spew carbon-laden smoke into the air. Meanwhile, nitrous oxide has risen due to the widespread use of nitrogen fertilizers and the intensification of agriculture.
“As these numbers show, we still have a lot of work to do to make meaningful progress in reducing the amount of greenhouse gases accumulating in the atmosphere,” said Vanda Grubišić, director of Noaa’s global monitoring laboratory.
The increasing presence of greenhouse gases is fueling a rise in global temperature – last year was the hottest ever recorded globally – and also associated impacts such as floods, droughts, heat waves and wildfires.
It also pushes the world into a state not seen since before human civilization. Carbon dioxide levels today are now comparable to what they were about 4 million years ago, Noaa said, an era when seas were about 75 feet higher than they are today, the average temperature was much warmer and vast forested areas of the now-frozen Arctic occupied territory.
Because of a lag between CO2 levels and their impact, as well as the hundreds of years the emissions remain in the atmosphere, the timescale of the climate crisis is enormous. Scientists have warned that governments must quickly reduce emissions to net zero and then remove carbon from the atmosphere to reduce future temperature rises.
