During the Southern Hemisphere’s summer of 2019–2020, mountains in New Zealand turned red. New research finally explains why.
Researchers have revealed that New Zealand’s Southern Alps turned red after a massive dust storm in southeast Australia sent clouds of red dust across the sea, dumping around 4,500 tons onto the snow. Their work, detailed in a study published in December of last year in the journal Geophysical Research Letters, corrects widespread assumptions that the contamination was caused by ashes from bushfires in Australia—and warns that such events could become more frequent in the future.
“Media reports in 2020 generally assumed the blanket of red on the mountains was caused by ash swept across the sea from Australia’s devastating New Year bushfires,” explained Holly Winton, lead author of the study and an environmental scientist at Te Herenga Waka—Victoria University of Wellington, in a university statement. “But the red dust that led to the dramatic colour change actually arrived well before New Year.”
Winton and her colleagues analyzed the red contamination by referencing time-lapse cameras, tracing the movement of air masses back in time, conducting snow impurity geochemical analyses, and relying on remote sensing operations. Their results indicate that the red dust came from southeastern Australia and arrived in New Zealand’s Southern Alps in late November of 2019.
“Fresh snowfall quickly buried the dust, but this surface snow melted away in early 2020, coinciding with spectacular skies over New Zealand associated with the Australian bushfires,” Winton explained in the statement. “Not surprisingly, the red mountains and the fires became linked in media reports.”
However, “the main driver of the glacier discoloration,” the researchers wrote in the study, was “a southeast Australian desert dust storm generated by the same type of meteorological conditions as the 2020 New Year bushfires.”
The layers of dust likely had a major impact on the mountains, because they reduced the snow’s ability to reflect sunlight. Instead, dust absorbs the light, which increases surface temperatures and, as a result, snow and ice melt, Winton added.
Furthermore, “climate change is expected to result in increased desertification and dry conditions in many areas so these storms—as well as wildfires that can be driven by similar weather patterns—are likely to occur more often,” explained Phil Novis, a co-author of the study and a phycologist from Manaaki Whenua Landcare Research. “The 2019/2020 event is at least the ninth such event recorded in Aotearoa New Zealand since 1902 and surely one of the most dramatic.”
The study highlights an event that dramatically changed New Zealand’s landscape and hopefully serves as a red flag, urging leaders to account for the less obvious environmental impacts of climate change.
English (US) ·