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The year 2024 was the most humid on record, along with being the hottest year on record with a temperature anomaly of 1.55°C, according to many experts and agencies. If the dangerous feedback loop of warming and moisture accelerates in the years ahead, it could mean even greater catastrophic impacts of warming combined with moisture.
This increased moisture drove many of the most intense extreme weather events in the year such as the devastating floods in Spain in October 2024, Hurricane Helene in the United States in September and the catastrophic floods in five African countries — Sudan, Nigeria, Niger, Cameroon and Chad — during August and September.
All these events have been attributed to global warming and consequent climate change by scientists from the World Weather Attribution consortium.
“Atmospheric moisture was above average for 86 per cent of Earth. A warmer planet is a wetter planet,” wrote Ben Noll, meteorologist for The Washington Post on the social media platform X.
“2024 surpassed 2016 to become the new moistest year on record. After the big El Niño events of 2015-16 and 2023-24, global moisture exhibited an upward step change,” Noll added.
There was a record amount of water vapour in the atmosphere in 2024, according to the European Union’s Copernicus Climate Change Service (C3S). C3S said the water vapour in 2024 was 4.9 per cent above the 1991-2020 average. This means that the water vapour was at its highest in at least 33 years.
The difference in the atmospheric moisture levels in 2024 from the previous record years is striking. Water vapour was 3.4 per cent higher than the 1991-2020 average in 2016 and 3.3 per cent higher in 2023.
Large parts of northeastern North America, the Sahara Desert in Africa, India, Russia and China in Asia and some parts of Australia and South America experienced the highest ‘total column water vapour’ as compared to 1992-2020 reference period.
‘Total column water vapour’ is “a measure of the amount of moisture in a vertical column of air extending from Earth’s surface to the top of the atmosphere,” according to C3S.
“The record high water vapour value for 2024 was influenced by a combination of increased surface evaporation from the ocean due to higher sea surface temperatures and by the ability of a warmer atmosphere to hold more moisture,” said C3S in its website.
The global average annual temperature anomaly as compared to the pre-industrial period (1850-1900) was above the 1.5°C threshold according the World Meteorological Organization (WMO). The WMO provided a consolidated analysis of six international temperature datasets to conclude a warming of 1.55°C above the pre-industrial period for 2024.
“It is important to emphasise that a single year of more than 1.5°C for a year does NOT mean that we have failed to meet Paris Agreement long-term temperature goals, which are measured over decades rather than an individual year,” said Celeste Saulo, secretary general of WMO, in a press release.
“However, it is essential to recognise that every fraction of a degree of warming matters. Whether it is at a level below or above 1.5°C of warming, every additional increment of global warming increases the impacts on our lives, economies and our planet,” Saulo added.
Another recent research paper published in the journal Advances in Atmospheric Sciences on January 10, 2025, had highlighted that sea surface temperatures (SSTs) and ocean heat content were record high in 2024 in response to greenhouse gases in the atmosphere.
This record, which was slightly higher than the previous record set in 2023 (by 0.07°C), was set despite the El Niño conditions turning to neutral conditions in the early part of the year. Global SSTs were on an average 0.61°C above the 1981-2020 baseline, according to the study.
El Niño is the warmer-than-normal phase of the El Niño Southern Oscillation phenomenon in the equatorial Pacific Ocean and generally leads to higher-than-normal surface air and sea surface temperatures and also increased or decreased rainfall in many places around the planet.
The deadly combination and feedbacks among rising atmospheric temperatures, SSTs, ocean heat content and atmospheric moisture could spell doom for the world in terms of extreme weather events and other slow onset changes such as sea level rise and glacial melting.
“Water vapour is a potent greenhouse gas. More water vapour equals more warming. More warming creates an atmosphere that can hold more water vapour. If this feedback loop accelerates, so will the precipitation extremes in the years ahead,” wrote Noll on X.