A record-breaking Sahara dust storm that spread hazy skies and harmful levels of air pollution across parts of North America was caused by winds linked to melting Arctic sea ice, researchers say.
The event, , peaked from 14 to 19 June 2020 and travelled more than 8000 kilometres across the Atlantic Ocean. The record dust plumes it created were so thick that algorithms initially classified them as clouds rather than dust. 鈥淚t was exceptionally severe,鈥� says Diana Francis at Khalifa University in Abu Dhabi, United Arab Emirates.
Now Francis and her colleagues have found an explanation for why this was such an intense dust storm by combing through satellite and climate data during the event. The key seems to have been a high-pressure system unusually located off the western coast of the Sahara desert. That led to the acceleration of north-easterly winds, which were then injected into one of the jet streams that crosses the Atlantic Ocean.
Advertisement
Finally, the high-pressure system lingered and caused the jet to be 鈥渂locked鈥� in place, much like similar blocking highs have influenced extreme weather in Europe and the US in recent years, leading to the particularly intense dust clouds seen between 14 and 19 June.
As Francis points out, such blocking patterns聽have been tentatively linked to Arctic sea ice loss, which was at . With the Arctic as climate change accelerates, that shift at the pole could plausibly lead to more frequent extreme dust events born in the Sahara desert. 鈥淎fter studying this case, I think we should expect the unexpected in terms of the response of the Sahara and the dust activity there, due to the changes occurring globally,鈥� says Francis.
The research is due to be published in the journal Geophysical Research Letters on Monday.
