Dust from desert storms and drylands has helped cool the planet over the past few decades, and its presence in the atmosphere may have obscured the true extent of global warming caused by fossil fuel emissions.
One analysis shows that atmospheric dust has increased by about 55% since the mid-1800s. And this increased dust may have masked 8% of the warming from carbon emissions.
Analysis by atmospheric scientists and climate researchers in the U.S. and Europe seeks to identify the diverse and complex ways in which dust affects global climate patterns and concludes that overall greenhouse gases attempt to somehow neutralize the warming effects. The study, published in the Nature Review Earth and Environment, warns that current climate models do not account for the impact of atmospheric dust.
“We’ve long guessed we’re headed for a bad place when it comes to greenhouse warming,” said Jasper Kok, an atmospheric physicist at UCLA who led the research. “What this research shows is that we’ve already applied the emergency brake.”
Scientists estimate that about 26 million tons of dust hangs in our atmosphere. Its effects are complex.
Dust, along with synthetic particulate pollution, can cool the planet in a number of ways. These mineral particles can reflect sunlight away from Earth and disperse cirrus clouds high in the atmosphere, which warms the planet. Dust falling into the ocean encourages the growth of phytoplankton (microscopic plants in the ocean) that absorb carbon dioxide and produce oxygen.
Dust can also have a warming effect in some cases – darkening snow and ice, allowing them to absorb more heat.
But after calculating everything, the researchers realized that the powder had an overall cooling effect.
“There are all these different factors that influence the role of mineral dusts in our atmosphere,” said Gisela Winckler. climate scientist at the Lamont-Doherty Earth Observatory at Columbia University. “This is the first review of its kind that really brings all these different aspects together.”
Winckler said that while climate models have so far been able to predict global warming with some accuracy, the review makes it clear that these estimates fail to detect the role of dust particularly well.
Limited records from ice cores, marine sediment records, and other sources indicate that dust in general has also increased since pre-industrial times – in part due to development, agriculture, and other human effects on landscapes. But the amount of dust also seems to have been declining since the 1980s.
More data and research are needed to better understand these dust patterns and better predict how they will change in the coming years, Winckler said.
But if the dust in the atmosphere is reduced, the warming effects of greenhouse gases can accelerate.
“Therefore we can start to experience warming up faster,” Kok said. “And maybe we wake up to this reality too late.”
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