Scientists in Abu Dhabi found that the mammoth 'Godzilla' dust storm that blew to the US from the Sahara in June may have been caused by lower ice levels in the Arctic.
Their research indicates that climate change may be having unexpected consequences for global weather patterns that extend well beyond temperature increases.
Godzilla was caused by thousands of tonnes of sand from the Sahara being lifted several kilometres into the sky before being blown westward across the Atlantic.
The storm blanketed major US cities such as Houston, Texas, with clouds of dust, much of which came from Mauritania, Mali and Niger at the southern edge of the Sahara.
In their paper, published in Geophysical Research Letters, researchers suggest that the low level of Arctic sea ice cover – which was at its least extent for decades in June this year – may have contributed to the conditions that caused Godzilla.
Arctic sea ice influences weather circulation around the world, said Dr Diana Francis, a senior scientist at Khalifa University in Abu Dhabi, and the paper's first author.
“Losing polar ice changes the temperature gradient between high latitudes and the tropics/subtropics, which is then translated into changes in the atmospheric circulation that, in turn, can be manifested in extreme events such as the Godzilla dust storm,” she said.
“In my view, it is not just by coincidence that the Arctic sea ice extent was the lowest on record in June 2020 and the most intense dust storm from the Sahara occurred also in June 2020. But more investigation is needed to establish the exact link.”
Godzilla resulted from a large-scale weather anomaly involving unusually strong north-easterly winds over the Sahara.
These winds were created because of a pressure gradient between a subtropical high off Africa's west coast and the monsoon low-pressure area and whipped up vast quantities of dust for days on end.
The scale and thickness of the huge plumes meant they were visible from space as they moved westward over the Atlantic before making landfall – and headlines – in the Caribbean and the US.
"The interconnections between weather patterns around the globe is well illustrated by the June event," Dr Francis said.
“The atmosphere is an efficient means by which changes in the climate over a certain region can [affect] another region in a very short period of time – in the order of a few days.”
Levels of Arctic sea ice have dropped by more than half in the past four decades and continue to drop by more than 10 per cent a year.
Because of the effects of Arctic sea ice, the scientists predict that severe dust storms could become more frequent.
“If such patterns become more common in a warmer world, it is plausible that these extreme dust outbreaks will increase in frequency in the future,” the researchers wrote.
While the latest work focuses on a dust storm in the US, previous research indicated that warming in the Arctic could be influencing sand storms in the UAE and other parts of the Gulf. Such events could become more common in this region too.
In a study last year, Dr Francis, along with other researchers, suggested severe dust storms in the Arabian Peninsula in September 2015 were linked to a warmer Arctic and changes in the circulation of the polar jet stream, a powerful wind pattern in the upper atmosphere.
"The frequency of extreme events in the Gulf region may increase in the future based on what we have seen in the past two decades and if the projected increase in desertification in the region is not mitigated by human-made initiatives such as planting trees and increasing vegetation cover," Dr Francis said.
In previous studies, some carried out while Dr Francis was at New York University Abu Dhabi, she and her colleagues identified other alterations in global circulation patterns resulting from a changing Arctic climate.
For example, as well as being blown to the US, sand from the Sahara gets transported to the Arctic itself and, because of climate change, is now travelling there by a more direct route.
Once there, as previously reported in The National, it can increase the absorption of sunlight, leading to greater melting of ice, which has consequences for the global climate.
The latest research was also authored by Khalifa University researchers Dr Ricardo Fonseca, Dr Narendra Nelli and Michael Weston, along with scientists in France and the US.