In 2024, Earth received about 2.9 millimetres of rain per day. That may not sound like much, but it could represent a new record amount of precipitation for the planet.
Last year鈥檚 global average precipitation was about 3 per cent greater than the average since records began in 1983, and it just surpasses the previous record, set in 1998. The 2.9-millimetre number, based on preliminary compiled by researchers at the Global Precipitation Climatology Project, may still change slightly as the data is finalised. But if it holds, it would make 2024 not only the hottest year on record, but also the rainiest.
That is no coincidence, says at the University of Maryland. Hotter temperatures enable the atmosphere to hold more moisture and increase the amount of evaporation from the ocean and land. However, temperature and precipitation don鈥檛 move in lockstep.
Advertisement
鈥淯nlike global temperature, which is going up pretty steadily, the global precipitation is just about constant, with a fairly high degree of variation year to year,鈥� says Adler.
Generally, the wettest years on record 鈥� like 1998 and 2016 鈥� have been associated with the development of a strong El Ni帽o weather pattern in the Pacific Ocean. This phenomenon tends to boost temperatures further, adding to the background rise from increasing levels of greenhouse gases.
A strong El Ni帽o did develop in 2023, but it petered out in the first half of 2024. In its absence, the high precipitation levels in 2024 are particularly interesting, says Adler. 鈥淭here may be some other things going on that enhanced the precipitation.鈥�
One possible driver was the throughout 2024, which boosted evaporation. Adler points to several 鈥渉otspot鈥� regions where high sea surface temperatures last year overlapped with areas that saw above-average precipitation, like the Caribbean and the Indian Ocean.
鈥淥verall, you expect a general increase in the hydrological cycle as the planet warms,鈥� says at the Scripps Institution of Oceanography in California, who wasn鈥檛 involved with the assessment. 鈥淪o what has happened in 2024 is in accord with how future changes are likely to play out.鈥�
While the global average precipitation reached a new high, it wasn鈥檛 evenly distributed. Much of South America and parts of western North America saw drier conditions, while areas like South-East Asia and central Africa were wetter than normal. This reflects a general pattern of climate change causing wet areas to get wetter and dry ones to get drier, says Adler. 鈥淚f it keeps going this way, it says that what happened in 2024 has reinforced the long-term trend.鈥�
Warming temperatures are also making extreme rain and flooding events more likely, even as they deepen droughts elsewhere in the world. Sudden swings between these 鈥� known as climate whiplash 鈥� are also becoming more frequent.
Climate whiplash has cascading effects for ecosystems and people. For example, the explosive wildfires in Los Angeles, California, have been partially fuelled by the combination of a wet 2023 boosting vegetation growth, followed by a hot and dry 2024 setting it up to burn.
