Why climate models miss the mark on Arctic warming – and how scientists are improving their accuracy
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Researchers have also warned that even limiting global warming to 1.5°C won’t save our polar ice sheets.
If you’re wondering why Arctic temperatures are rising so much faster than predicted, scientists at Kyushu University think they’ve found an answer: it’s in the clouds.
In a study published in Ocean-Land-Atmosphere Research, researchers from Kyushu University analysed 30 leading climate models and compared them to satellite observations of Arctic cloud patterns. They discovered a widespread modelling error.
Most simulations overestimate the amount of ice and underestimate the amount of liquid in wintertime Arctic clouds.
That may sound like a small detail, but it has big consequences for how accurately scientists can predict warming in one of the world’s most sensitive regions.
Clouds could be acting like a thermal blanket over the Arctic
The Arctic is warming three to four times faster than the global average. A major reason for this is how clouds interact with heat.
In summer, so-called mixed-phase clouds – which contain both ice crystals and supercooled liquid water – reflect sunlight, cooling the surface. But in the dark winter months, these same clouds trap heat and insulate the surface like a thermal blanket.
“The more liquid water these clouds contain, the better they are at trapping heat,” explains study co-author Momoka Nakanishi.
Most models, however, suggest that clouds have less ice in them than they do. That could explain why the rate of Arctic warming in recent decades has outpaced predictions. It could also warp future projections – but not in the way you might think.
The future may be less dire than it seems – but the present is worse
As the Arctic continues to warm, more ice in clouds converts to liquid, increasing their heat-trapping power. This creates a short-term condition known as “cloud emissivity feedback,” which accelerates warming. But, the researchers add, there’s a limit to it.
Once clouds are rich enough in liquid, they begin to absorb heat and re-emit it to Earth completely. Meaning, additional warming makes little difference, because the clouds are already re-emitting heat to the maximum extent possible.
Since many climate models don’t accurately represent how much liquid is already present, they could be predicting greater warming than is likely in the future.
In other words, they underestimate today’s warming and overestimate tomorrow’s.
Fixing this flaw, researchers argue, could improve not just Arctic projections but also extreme weather forecasts in other parts of the world, which are influenced by polar systems.
The damage could already be done
The study adds context to another sobering piece of research, published earlier this month in Communications Earth & Environment.
That study found that even if global warming is limited to 1.5°C, we could still trigger irreversible melting in the massive polar ice sheets in Greenland and Antarctica, leading sea levels to rise several metres even under optimistic emissions scenarios.
Both studies point to the same truth: our understanding of polar regions, from clouds to ice melt, is still catching up with reality.
If climate models continue to lag observed trends, the world could be blindsided by faster-than-expected changes in sea level, weather extremes and ecosystem collapse.
As cloud study co-author Takuro Michibata put it, “Fixing these models is essential not just for the Arctic, but for understanding its impact on weather and climate change across the globe.”
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