El Niño an global heatin pushes watter vapour in Earth’s atmosphere tae record levels in August

The planet’s atmosphere held mair watter vapour in August than ony ither month on record, furthir increasin the risk o extreme heat an rainfall roond the warld, accordin tae Europe’s climate change service.

Climate scientists said global heatin wis a contributor tae the record because a warmer atmosphere can haud mair watter, an the historic El Niño in the Pacific Ocean wis also likely pushin watter vapour levels up.

Accordin tae the Copernicus Climate Change Service (C3S), the amoont o watter vapour in the atmosphere throu August wis 27.35 kg per square metre, beatin the previous record frae Julie 2024 by 0.04 kg m².

The value describes hou muckle watter vapour is in a column o air sittin abuin a square metre o the Earth’s surface, extendin up throu the atmosphere.

The 0.04 kg m² increase on the previous record, ane climate scientist calculated, wis the equivalent o aboot 20 trillion litres o additional watter, or 20 cubes o watter, each a kilometre wide, heich an deep.

Dr Julien Nicolas, senior scientist at C3S, said watter vapour wis estimated in its ERA5 dataset by combinin humidity measurements frae satellites, balloons an ither sources wi a weather model. The watter vapour estimates gang back tae 1979.

August wis also the planet’s joint hottest month on the ERA5 dataset goin back tae 1940, an the hottest accordin tae the US government’s National Oceanic an Atmospheric Administration dataset that starts in 1850.

Nicolas said the watter vapour record wis consistent wi the record heich global temperature in August an said warmer air can haud aboot 7% mair watter vapour per degree o global heatin.

He said the tropical oceans were a major soorce o the watter vapour.

The exceptionally heich sea surface temperatures seen across these regions in August, partly linked tae the presence an strengthenin o El Niño conditions, increased evaporation an were likely an important contributor tae the record-heich global watter vapour value.

He said risin watter vapour levels cud increase the risk o intense rainfall, includin frae cyclones, an gie extra energy tae storms because heat is released whan watter vapour condenses intae cloud droplets, potentially helpin tae intensify them.

The current El Niño climate pattern in the tropical Pacific is forecast tae be the strangest on record an climate scientists predict it cud push global temperatures tae record levels neist year.

Provisional analysis by Australian scientists has foond the expected record peak ocean temperatures in the Pacific that are a marker o the El Niño were bein made sax times mair likely because o global heatin.

Dr Andrew Dessler, a climate scientist at Texas A&M University, wrote that it wis unimaginable that ony month in the last few thoosan years, maybe 100,000 years, had had mair watter vapour in the atmosphere than August.

We are, as the proverb says, livin in interestin times, he wrote.

Prof Steven Sherwood, o the University o New Sooth Wales Climate Change Research Centre, said while an extra 0.04 kg m² o watter vapour across the planet doesna soon like a lot, whan this rise is continuous, it starts tae hae effects.

A lot o the impacts o climate change actually happen because o watter vapour.

Whan ye muve this watter vapour tae heicher latitudes, it puts heat intae the air, an sae a lot o extreme heat that is experienced there is indirectly frae the watter vapour.

We ken heich humidity has effects durin heatwaves as it stops nicht-time coolin, sae it gets harder for fowk tae recover frae very hot days.

Prof Jason Evans, also o the UNSW climate centre, calculated the watter vapour record had exceeded the previous record by the equivalent o aboot 20 trillion litres, or aboot 41 Sydney Harbours’ worth o watter.

Dr Kimberley Reid, a climate scientist at the University o Melbourne specialisin in watter vapour research, said given August wis the hottest month for at least 170 years, this record isna ower shockin.

Temperature an watter vapour are closely linked, she said. Like the temperatures, we are gettin these records because o the emissions frae burnin fossil fuels an frae the El Niño.

Watter vapour is also part o the climate feedback loop, watter vapour is a greenhouse gas an sae the atmosphere will warm even furthir, an than tak up even mair watter vapour. The root cause is the extra CO2 an methane.