Thick ash from the Australian bushfires has coated glaciers in New Zealand, and blown across the Tasman Sea to settle on the pristine ice.
It's turned clean, white snow yellow and grey, and could impact how quickly it melts.
Pictures from the Franz Josef and Tasman glaciers in the South Island show dull scenes, the glaciers "caramelised" by the dust and ash .
That coating will likely increase the melt of the glaciers, University of Waikato's Professor Craig Cary told 1 NEWS.
"There's always a concern that the melt rate would increase," he says.
It's because the dust is darker than the snow. The albedo measures how much light hitting a surface is reflected, instead of being absorbed.
The darker particles absorb more incident radiation from the sun, generating more warmth, than the white snow around it, Prof Cary says.
He says the same principle is why you burn your feet on hot asphalt in summer, compared to grass beside it.
"The dust has a tendency, when there is melt, to pool together... A lot of the real problems when the dust comes together and forms those high concentration pockets. They will melt much, much quicker."
Thousands of people need to escape Australia’s bushfire-affected coastal towns, including tourists.
However Prof Cary says it doesn't mean the glaciers are going to collapse right away.
"That ice is pretty old and hard. The ice itself is pretty tough. It would take a prolonged period of summer and a lot of that dust coming over for it to be noticeable, for the short-term process," he says.
"If they continue to burn and we continue to have this input [of ash]… it's the accumulation that's going to get you.
"But it takes time. We're not going to lose the glaciers overnight, that's for sure."
A heavy layer of snowfall is enough to stop the process, Prof Cary says, if it buries the ash.
"But if it doesn't get buried then the process can continue, over and over and over again."
Prof Cary warns with the changing climate , "everything's up for grabs now".
"The way the climate is changing, the amount of time period of warmth and cold, droughts - who knows what's going to happen," he says.
"For sure, any type of reduction in albedo is going to be detrimental to an ice surface because it's going to melt."
Smoke plumes drifting over from Australia have turned skies across New Zealand yellow and hazy , cloaking the sun in places.
WeatherWatch says it may continue until Sunday.
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