Global — Scientists know that air pollution particles from mid-latitudecities migrate to the Arctic and form an ugly haze, but a new University of Utahstudy finds surprising evidence that polar explorers saw the same phenomenon asearly as 1870.
The reaction from some colleagues when we first mentioned that people hadseen haze in the late 1800s was that it was crazy, says Tim Garrett,assistant professor of meteorology and senior author of the study. Who wouldhave thought the Arctic could be so polluted back then? Our instinctive reactionis to believe the world was a cleaner place 130 years ago.
The study will be published soon in the March 2008 issue of the Bulletin ofthe American Meteorological Society.
By searching through historic records written by early Arctic explorers, Garrettand his collaborator Lisa Verzella, former undergraduate student at theUniversity of Utah, were able to find evidence of an aerosol dry haze thatsettled onto the ice to form a layer of grayish dust containing metallicparticles. The haze and dust were likely the byproducts of smelting and coalcombustion generated during the Industrial Revolution.
We searched through open literature, including a report in the second issueof the journal Science in 1883 by the famous Swedish geologist Adolf ErikNordenskiold, who was the first to describe the haze, says Garrett. Wealso looked through books describing Arctic expeditions that had to betranslated from Norwegian and French.
The historic accounts show that more than 130 years ago, the IndustrialRevolution was already darkening the snow and skies of the far North,Garrett says.
History of Arctic Pollution
Garrett and Verzella say the first report of Arctic haze pollution usually iscredited to a U.S. Air Force meteorologist J. Murray Mitchell, who in 1957described the high incidence of haze at flight altitudes during weatherreconnaissance missions from Alaska over the Arctic Ocean during the late 1940sand 1950s.
Mitchell was credited in the 1970s by Glenn Shaw from the University of Alaska,Fairbanks, and his collaborators Kenneth Rahn and Randolf Borys, from theUniversity of Rhode Island, who were the first to discover the haze containedhigh levels of heavy metals, including vanadium, suggestive of heavy oilcombustion.
In a later study, Rahn and Shaw said: Arctic haze is the end product ofmassive transport of air pollution from various mid-latitude sources to thenorthern polar regions, on a scale that could never have been imagined, even bythe most pessimistic observer.
Since humans had been generating aerosol pollution long before 1950 namely,since sometime after the advent of the Industrial Revolution in the late 1700s it made sense to Garrett that pollution generated from earlier times alsomight have made it to northern latitudes from Europe, Asia and North America.
I thought that pollution had to be observed in the Arctic prior to 1950, so Idecided to find out if that was true, says Garrett. So he hired Verzella tosearch historic records to determine if there was written evidence of earlyArctic pollution.
Verzella found a number of published reports from the late 1800s to early 1900sthat mention a whitish haze in the sky, or a gray or black dust on the ice. ButNordenskiold was the first to explicitly draw attention to the hazephenomenon during his 1883 expedition to Greenland, the researchers concluded.
Even during an earlier expedition in 1870, Nordenskiold observed a fine dust,gray in color, and, when wet, black or dark brown, is distributed over theinland ice in a layer which I should estimate at from 0.1 to 1 millimeter.
He found that the dust contained metallic iron, which could be drawn out bythe magnet, and which, under the blowpipe, gave a reaction of cobalt and nickel.He believed it to be a cosmic dust possibly from meteors. However, theconcentration of metallic iron, nickel and cobalt made it much more likely thatthe origin was industrial pollution generated at mid-latitudes.
Last year, other researchers found that the dust is present in ice core samples.Recent Greenland ice cores show a rapid rise in anthropogenic soot andsulfate that began in the late 1800s, but with peak sulfate levels in the 1970s,and peak soot between 1906 and 1910, Garrett and Verzella say in their study.A higher composition of sulfate suggests oil combustion, while higher sootsuggests coal combustion, consistent with the main sources of pollutiongenerated in the 20th versus 19th centuries.
Early Arctic Warming
In a 2006 study, Garrett concluded that particulate pollution from mid-latitudesaggravates global warming in the Arctic. Did it do the same back in the 1800s?
It is reasonable that the effect of particulate pollution on Arctic climatemay have been greater 130 years ago than it is now, because during theIndustrial Revolution, technologies were dirtier than they are now, saysGarrett. Of course, today carbon dioxide emissions are greater and haveaccumulated over the last century, so the warming effect due to carbon dioxideis much greater today than 100 years ago.
In fact, after fossil-fuel combustion became more efficient in the mid-1900s,the levels of particulate pollution in the Arctic dropped dramatically fromlevels earlier in the century. However, Garrett believes that we might be seeinganother increase due to higher emissions from developing industrial countriessuch as China.