The dust that rises from desert climates and arid landscapes has helped cool the planet for several decades, and its presence in the atmosphere has obscured the true extent of global warming from fossil fuel emissions.
Atmospheric dust has increased by about 55% since the mid-1800s, the analysis suggests. And that growing dust can hide up to 8% of the warming from carbon emissions.
Analysis by atmospheric scientists and climate researchers in the US and Europe attempts to report the various and complex ways in which dust affects global climate patterns, concluding that overall, it has worked somewhat against the warming effect of greenhouse gases. The study, published in Nature Reviews Earth and Environment, warns that current climate models fail to account for the effect of atmospheric dust.
“We’ve long predicted that we’re headed for a bad place when it comes to greenhouse warming,” said Jasper Kok, an atmospheric scientist at UCLA who led the research. “What this research shows is that time has broken on us.”
About 20,000 tons of dust are suspended in our atmosphere, scientists estimate. Its results are complex.
Dust, along with synthetic particulate pollution, can cool the planet in many ways. These particular minerals are able to reflect sunlight away from Earth and disperse cirrus clouds high in the atmosphere, which warms the planet. The dust that falls into the ocean encourages the growth of phytoplankton – microscopic plants in the ocean – which absorb carbon dioxide and produce oxygen.
Dust can also in some cases have a warming effect – darkening snow and ice, and pushing them to absorb more heat.
But after everything was agreed upon, it was clear to the researchers that the dust had a higher cooling effect.
“There are all these different factors that play into the role of mineral dust in our atmosphere,” said Gisela Winckler, a climate scientist at the Lamont-Doherty Earth Observatory at Columbia University. “This is the first review of its kind to really bring all these different aspects together.”
Although climate models have so far been able to predict global warming fairly accurately, Winckler said the review revealed that these predictions have not been able to pinpoint dust particles particularly well.
Limited records from ice cores, marine sediment records, and other sources suggest that dust levels were already growing higher even before industrialization—in part because of development, agriculture, and other human impacts on landscapes. But the amount of dust also seems to have decreased since the 1980s.
More data and research is needed to better understand these dust patterns, Winckler said, and to better predict how they will change in the coming years.
But if dust in the atmosphere decreased, the warming effects of greenhouse gases could accelerate.
“We were able to experience faster and faster warming because of this,” Kok said. “And maybe we’re waking up to that too late.”
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