Globe Crossing Dust Storms Nothing New
Conceptual image of dust from the Saharan Desert crossing the Atlantic Ocean to the Amazon rainforest in South America. Image via Conceptual Image Lab, NASA/Goddard Space Flight Center[1]
Globe-crossing dust storms are nothing new
By Dale Mayo
In spring and summer, the Caribbean region and tropical North Atlantic typically experience moderate to heavy episodes of airborne African dust concentrations that blow in from the Sahara Desert. These dust episodes are often contained within the Saharan air layer (SAL), an elevated air mass marked by very dry and warm conditions in the lowest levels.[2] The Saharan air layer brings several hundred million tons of dust across the ocean each year.[3] The recent dust storm was historic because of its dense concentration of dust.[4] It traveled several thousand miles across the Atlantic from the Sahara and followed a typical path – after arriving in the Caribbean, the dust dispersed up the east coast past the Carolinas and across the Gulf of Mexico to Texas and Oklahoma. Dust storms also regularly blow from Asia across the Pacific to the west coast of North America. These global storms affect weather, soil nutrients, coral reefs, and even glacier composition.
Non-Sahara dust storms
In the US, dust storms and haboobs[5] are most common in the Southwest. Blinding, choking dust and debris can strike with little warning and while they usually last only a few minutes, they reduce visibility making driving hazardous.[6] Reed Timmer posted a 7.5 minute video on YouTube of a giant dust storm that resulted from severe storms in the Phoenix area: Full evolution of MEGA HABOOB in southern Arizona on July 10, 2018! But sometimes haboobs originate in the Arctic - the picture (below) of a dust storm from the Arctic was taken from a plane flying over Colorado.
Arctic dust storm over Colorado. Photograph taken by Amanda Wicks on November 10, 2014[7]
While the Sahara is the largest single source of wind-blown sediments,[8] other deserts and climate events also produce large dust storms elsewhere in the world. In April 2001 a windstorm from the Siberian plateau stirred up dust from the Gobi desert in Mongolia and the Taklamakan desert in China and spread over China, Korea, and Japan. Dust clouds reached North America in a week and eventually got as far east as the Canary Islands. Fine aerosols, including mercury from space heaters and arsenic from smelters, stayed in the dust clouds. According to a member of the ACE-Asia team studying fine atmospheric particles during the event, “ The highest level of arsenic we ever saw in Nevada came from Manchuria.” Such pollutants are thought to absorb and redistribute far more heat in the atmosphere than typical aerosols found in the Sahara dust storms. [9]
Saharan dust
Scientists are attempting to reconstruct the African dust deposition in sediments from the Bahamas and tropical North Atlantic spanning the last 23,000 years.[10] This would allow investigations into the role of Saharan dust in past climate change, especially the mid-Holocene (from approximately 7,000 to 5,000 years ago) which paleoclimatologists suspect was warmer than the present day.[11] The relationship between dust and climate is complicated as they affect one another – dust dropped into the ocean provides nutrients that affect the global carbon cycle and dust is generated and transported by climate.[12]
… a boon for the Amazon rainforest
We know that the amount of rainfall in the Sahel along the southern edge of the Sahara directly affects how much dust arrives in the South America in the region of French Guiana, the Amazon, and the Caribbean.[13] The minerals and nutrients carried from Africa appear to provide the Amazon rain forest with exactly what it needs – in the dust is phosphorus, an essential nutrient that acts like a fertilizer.[14] A short (two minute) NASA video on YouTube (NASA | Satellite Tracks Saharan Dust to Amazon in 3-D) shows what we have learned from satellite technology about how the phosphorus is distributed from Africa to the Amazon by dust storms. The storms vary in size from year to year, but an average of approximately 27 million tons per year[15] is just enough to replace the phosphorus lost to rain and flooding.[16]
"View from Tower" by Nagyman is licensed under CC BY-SA 2.0
Another benefit of Saharan dust storms is that when they cross the Atlantic, we generally have fewer hurricanes. Hurricanes need moist air and calm wind, but a dry and dusty Saharan air layer discourages their development and the dust appears to block incoming sunlight enough to keep ocean temperatures lower than needed to feed tropical storms.[17]
…but maybe not for coral reefs or humans
Saharan dust can have negative consequences, too. Algae in oceans and lakes feed on the iron-rich dust that is dropped and multiply at unusually rapid rates causing algal blooms or red tides that can kill fish and irritate human skin and respiratory systems.[18] Saharan dust is also linked to pathogens that cause coral reef decline – the decline in the Caribbean started in the 1970s at the same time the Saharan Air Layer began to increase significantly.[19]
These dust events can be hazardous for people living in and near the Caribbean, as the airborne dust levels often exceed healthy respiratory limits. Asthma is a significant problem in Puerto Rico and is worsened by high concentrations of dust.[20]
… and mixed effects on sea life
While dust storms can produce algal blooms that consume much of the dissolved oxygen in an area and create a dead zone, most of the time the nitrates, phosphates, and iron in the dust feeds phytoplankton. Phytoplankton provide food for a wide range of sea creatures including whales, shrimp, snails, and jellyfish.[21] In addition to their role at the bottom of the ocean’s food chain, plankton ecosystems play an important role in the ocean’s carbon cycle (see diagram at https://earthobservatory.nasa.gov/features/CarbonCycle).[22]
… and seafood
Dust storms provide needed fertilizers not only for the Amazon rainforest but also for phytoplankton, the foundation of the oceanic food chain. Plankton is essential to maintain fishery yields in the North Atlantic and elsewhere. This makes dust storms a benefit for the seafood industry.
Sizzlefish.com is a purveyor of high quality seafood from the Americas and North Atlantic – including red grouper (from the Florida Gulf), sea scallops (mid- to north-Atlantic coast), wild gulf (of Mexico) shrimp, sablefish (from Alaska and California), mussels (from the North Atlantic), and cod and haddock (north Atlantic). We use our many years of experience sourcing, preparing, and packaging seafood in supplying all the first-quality seafood that our customers have come to expect from us. Eating natural seafood is not only good our customers and for the men and women who work the waters to provide this bounty, but also for earth, with natural, sustainably sourced seafood. You can trust us to supply you with pure natural fish portions, with tools and tips for quick easy preparation, and with honest information about the benefits you are receiving from Sizzlefish.com products.
… and sunsets
References
[1] Byrd, Deborah. Saharan dust feeds Amazon rainforest, perfectly. Earth | Science Wire. EarthSky.org. February 24, 2015. https://earthsky.org/earth/saharan-dust-feeds-amazon-rainforest-perfectly
[2] Kuciauskas, Arunas P., et al. Supporting weather forecasters in predicting and monitoring Saharan air layer dust events as they impact the greater Caribbean. Bulletin of the American Meteorological Soc. (2018) 99 (2): 259-268. https://journals.ametsoc.org/bams/article/99/2/259/70373/Supporting-Weather-Forecasters-in-Predicting-and
[3] Kaplan, Sarah. How dust from the Sahara fuels poisonous bacteria blooms in the Caribbean. The Washington Post. May 11, 2016. https://www.washingtonpost.com/news/speaking-of-science/wp/2016/05/11/how-dust-from-the-sahara-fuels-poisonous-bacteria-blooms-in-the-caribbean/
[4] Sahara desert dust storm moves into US. ABC7.com – Weather. June 26, 2020. https://abc7.com/saharan-dust-godzilla-cloud-storm-2020-african/6268321/
[5] Haboobs (from the Arabic word habb, wind) are strong winds that associated with large sandstorms and dust storms in Sudan along the southern edge of the Sahara – the name is also used for storms in the Arabian peninsula, North America, Australia, and Asia.
[6] https://www.weather.gov/safety/wind-dust-storm
[7] https://www.nbcnews.com/news/photo/arctic-haboob-dust-storm-sweeps-over-colorado-n245946
[8] Van der Does, Michelle, P. Knippertz, et al. The mysterious long-range transport of giant mineral dust particles. Science Advances. December 12 2018: vol. 4, no. 12, eaau2768. https://advances.sciencemag.org/content/4/12/eaau2768
[9] Irion, Robert. The perfect dust storm. Science Magazine. December 12, 2001. https://www.sciencemag.org/news/2001/12/perfect-dust-storm
[10] Williams, Ross H., D. McGee, et al. Glacial to Holocene changes in trans-Atlantic Saharan dust transport and dust-climate feedbacks. Science Advances. November 23, 2016. Vol. 2, no. 11, e1600445 https://advances.sciencemag.org/content/2/11/e1600445
[11] Mid-Holocene warm period – about 6,000 years ago. https://www.ncdc.noaa.gov/global-warming/mid-holocene-warm-period
[12] Prospero, Joseph M. Characterizing the temporal and spatial variability of African dust over the Atlantic. Past Global Changes Magazine, vol. 22(2), 68-69, 2014. http://pastglobalchanges.org/products/pages-magazine/7254
[13] Prospero, Joseph M. Characterizing the temporal and spatial variability of African dust over the Atlantic. Past Global Changes Magazine, vol. 22(2), 68-69, 2014. http://pastglobalchanges.org/products/pages-magazine/7254
[14] NASA Satellite reveals how much Saharan dust feeds Amazon’s plants. February 22, 2015. Last updated August 7, 2017, Rob Garner, editor.
[15] Gray, Ellen. Massive amounts of Saharan dust fertilize Amazon rainforest. AGU blog GeoSpace. February 24, 2015. https://blogs.agu.org/geospace/2015/02/24/new-study-quantifies-amount-saharan-dust-feeding-amazon-rainforest/
[16] Byrd, Deborah. Saharan dust feeds Amazon rainforest, perfectly. Earth | Science Wire. EarthSky.org. February 24, 2015. https://earthsky.org/earth/saharan-dust-feeds-amazon-rainforest-perfectly
[17] NASA – Earth Observatory. Tracking dust across the Atlantic. August 29, 2013. https://earthobservatory.nasa.gov/images/81864/tracking-dust-across-the-atlantic?src=on-this-day
[18] Means, Tiffany. 5 things to expect from the massive Sahara dust plume. The Farmers’ Almanac. June 23, 2020. https://www.farmersalmanac.com/what-sahara-dust-plume-130096
[19] Saharan dust: the good and the bad. GoToStCroix.com. Jennie Ogden, editor. As seen July 3, 2020. https://www.gotostcroix.com/climate-weather/saharan-dust-the-good-and-the-bad/
[20] Kuciauskas, Arunas P., et al. Supporting weather forecasters in predicting and monitoring Saharan air layer dust events as they impact the greater Caribbean. Bulletin of the American Meteorological Soc. (2018) 99 (2): 259-268. https://journals.ametsoc.org/bams/article/99/2/259/70373/Supporting-Weather-Forecasters-in-Predicting-and
