2024 was the warmest year ever recorded and 1.55 degrees warmer than the second half of the 1800s, according to WMO's flagship report "State of the climate".
The causes of the high temperature are human emissions of greenhouse gases, which coincided with the El Niño phenomenon last year.
Something that has surprised me, as someone who follows global temperatures month by month, is the string of record-warm months that occurred from 2023 onwards. It has been exceptional, says John Kennedy, lead author of the report.
A warmer climate means more extreme weather such as droughts and worse hurricanes, and according to the report, a record number – hundreds of thousands of people – were forced to flee last year due to disasters exacerbated by climate change. WMO notes, however, that a third of the world's population lacks access to early warning systems. This can include warnings for heavy rainfall, which can lead to sudden flooding.
It's something we really need to work much more on globally to build capacity for, to save lives and resources, says Erik Kjellström, professor of climatology at SMHI.
The ocean absorbs heat
The carbon dioxide emitted in the coming years will add to the warming.
Once we've emitted that carbon dioxide, it won't disappear for a very, very long time. It will take centuries or even longer before the carbon dioxide eventually disappears, says Kjellström.
Most of the heat caused by the greenhouse effect is absorbed by the oceans, which are warming up to great depths. This is a development that cannot be reversed, and we will have to live with the consequences for hundreds if not thousands of years, warn the researchers.
Rising sea temperatures lead to problems such as coral bleaching and, since warm water expands, also to rising sea levels.
The Paris goal lives on
2024 is the first year that global warming has exceeded 1.5 degrees. But WMO emphasizes that this does not mean that the Paris Agreement's goal of keeping global warming below that limit is dead, since the goal concerns a longer period of time.
Depending on how you calculate it, the long-term warming is in the range of 1.34–1.41 degrees, according to the report. The average from 2015 to 2024 is 1.25 degrees.
There are several gases in the atmosphere that contribute to the greenhouse effect.
Carbon dioxide is the most important one that humans contribute to. The amount of carbon dioxide in the atmosphere continues to rise. In 2023, which is the latest year for which global figures are available, the level reached 420 million parts per million (ppm). This is 2.3 ppm more than in 2022 and 151 percent of the pre-industrial level.
Carbon dioxide levels have not been this high in at least two million years.
The levels of the greenhouse gases methane and nitrous oxide also reached record levels in 2023. Methane reached 1,934 billion parts and nitrous oxide 337 billion parts, 265 and 125 percent of the pre-industrial levels, respectively. The concentrations of these gases have not been this high in 800,000 years.
