Changing clouds adding to climate uncertainty as the world warms

People have always studied the skies to predict the weather but recently scientists have noticed that clouds are changing on a global scale posing one of the greatest challenges to understanding our warming worldSome clouds are rising higher into the atmosphere where they trap more heat Others are reflecting less sunlight or shrinking and allowing more solar energy to reach Earths surfaceScientists know this is affecting the climate because the vital role that clouds play in warming and cooling the planet is well understoodRecent research has shown that clouds or rather a lack of them helped drive a stunning surge in recordbreaking global heat over the last two yearsWhat is less certain is how clouds might evolve as the world warms Will they have a dampening effect on global warming or amplify it And if so by how muchThats why clouds are the greatest challenge Figuring them out is and has been the big roadblock said Bjorn Stevens from the Max Planck Institute for Meteorology in Germany who has written extensively on the subjectCloud behaviour is notoriously complex to predict and remains a great unknown for scientists trying to accurately forecast future levels of climate changeChanges in clouds could mean that even with the same amount of heattrapping greenhouse gas emissions we could get much more warming or much less warming said Robin Hogan principal scientist at the European Centre for MediumRange Weather ForecastsThats a big scientific uncertainty he told AFPWith satellites and supercomputers scientists are improving cloud modelling and slowly filling in the missing pieces of the puzzle Vicious cycle Part of the difficulty is that clouds are not uniform they act differently depending on their type structure and altitudeFluffy lowhanging clouds generally have a cooling influence They are big and bright blocking and bouncing back incoming sunlightHigher streaky ones have a warming effect letting sunlight trickle through and absorbing heat reflected back from EarthIn recent decades scientists have observed a growing imbalance between the amount of energy arriving rather than leaving Earth hinting at cloud changesAs the climate has warmed certain clouds have drifted higher into the atmosphere where they have a stronger greenhouse effect said HoganThat actually amplifies the warming he saidThis is growing evidence that lower clouds are also changing with recent studies pointing to a marked decline of this cooling layerLess reflective cloud exposes more of Earths surface to sunlight and boosts warming in a vicious feedback cycle said climate scientist Richard Allan from the University of ReadingIn March Allan coauthored a study in the journal Environmental Research Letters that found dimmer and less extensive lowlying clouds drove a doubling of Earths energy balance in the past 20 years and contributed to record ocean warmth in 2023A study in December published in the journal Science also identified a sharp drop in lowlying cloudinessas a likely culprit for that exceptional warmingStevens said scientists generally agreed that Earth had become less cloudy but there are a number of theories about the causesClouds are changing And the question is how much of that change is natural variability just decadal fluctuations in cloudiness and how much of that is forced from the warming he said No smoking gun Another theory is that decadeslong global efforts to improve air quality are altering the formation properties and lifespan of clouds in ways that are not yet fully understoodClouds form around aerosols tiny airborne particles like desert dust and sea salt carried on the wind or pollution from human activity like burning fossil fuelsAerosols not only help clouds take shape but can make them more reflectiveRecent research has suggested that clean air policies particularly a global shift to lowsulphur shipping fuel in 2020 reduced cloud cover and brightness inadvertently pushing up warmingAllan said aerosols were one factor but it was likely lower clouds were also melting away as the climate warmedMy feeling is theres a combination of things Its never one simple smoking gun he saidNew tools are chipping away at the uncertaintyLast May European and Japanese space agencies launched EarthCARE a revolutionary satellite capable of capturing unprecedented detail of inner cloud workingsIn orbit it joins PACE a cuttingedge NASA satellite also studying aerosols clouds and climate that lifted off just three months earlierOther recent innovations including in machine learning were helping bridge the gap in cloud understanding said Kara Lamb a research scientist and aerosols expert at Columbia UniversityWe are seeing progress over time she told AFPThis story has been sourced from a third party syndicated feed agencies Midday accepts no responsibility or liability for its dependability trustworthiness reliability and data of the text Midday managementmiddaycom reserves the sole right to alter delete or remove without 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