It’s no secret that humans have made major changes to the Earth and its atmosphere. But as greenhouse gases accumulated in the air and the average surface temperature of our planet rose, a less well-known phenomenon occurred.
Earth’s atmosphere has become much dustier since the pre-industrial era. And it’s possible that all of these extra particles are subtly working to counter some of the effects of climate change — cooling the planet a bit, according to Review study It was published Tuesday in the journal Nature Reviews Earth & Environment.
According to the new analysis, the effects of atmospheric dust are absent from almost all climate studies and projections. Meaning, these models can underestimate the warming associated with human-caused climate change. And if the atmosphere becomes less dusty, we could see rapid temperature rises.
“We want climate projections to be as accurate as possible, and this increase in dust could mask up to 8% of global warming,” said Jasper Cook, the study’s principal investigator and an atmospheric physicist at the University of California, Los Angeles. Press release. He continued that by adding dust effects to future climate models, scientists can improve them. “This is critical because better predictions can help make better decisions about how to mitigate or adapt to climate change.”
Cook and colleagues arrived at this 8% figure via a complex set of models, building on a wealth of previously published studies.
First, they had to figure out how atmospheric dust has changed over time. Using computer modeling and existing data from ice cores and sediment records, they found that the amount of large dust particles in the atmosphere has gone up by about 55% in the present, compared with the pre-industrial age. The reasons behind our increasingly dusty Earth are multitude, but it comes down to land use changes like increased agriculture and development, along with climate shifts like drought, according to the researchers.
Then, the study authors had to determine the overall climate effects of that dust.
Dust interacts with the climate in lots of different ways. Through scattering and absorbing heat from the Sun and Earth’s surface, dust particles can both cool and warm the planet. Dust can, for instance, reflect heat from the Sun back into space. Or, it can absorb and hold onto heat radiating off of Earth itself. The effects also vary based on region: Dust over reflective deserts, ice, and snow increases warming, whereas dust over oceans and dark forests leads to cooling.
The direction and magnitude of dust’s impact on global temperature further depends on factors like particle size, the wavelength of the radiation involved, and the landcover beneath the atmospheric dust. Dust can also chemically react with water and other compounds in the atmosphere to shift heat around, and dust particles can change cloud cycles. Finally, dust that eventually settles into water carries nutrients with it, and so can increase phytoplankton productivity and boost the amount of carbon dioxide our oceans absorb—indirectly affecting climate change.
TL;DR: It’s difficult to figure out exactly how and by how much atmospheric dust is really shifting global temperature. To get to their final estimate, Kok and crew calculated the heat effects of 12 different dust-related parameters—some in which dust increased warming and some in which it contributed to cooling— and added them all together. They found the net energy flux was somewhere between “substantial cooling” (-0.7 +/- 0.18 Watts per square meter) and “slight warming” (+0.3 Watts per square meter), with a median of -0.2 W/square meter. Hence, a calculated maximum cooling effect of about 8%.
Past research has documented how particle and aerosol Pollution can cause global cooling. For example, colder temperatures are a known side effect of Some volcanic eruptionsand a whole subset of Geoengineering hinges on this concept. But Tuesday’s review is fresh for its focus on naturally occurring dust.
Their model isn’t perfect, and the researchers note that there is a lot of uncertainty in their calculations — in large part because they were among the first scientists to attempt such estimates. “This is the first review of its kind that really brings all of these different aspects together,” Gisela Winkler, a climate scientist at Columbia University who was not part of the new research, said. he told the Guardian. But for all this uncertainty, the study says, “Dust is more likely to cool the climate than warm it” — bad news for our understanding of climate change.
“We’ve long predicted that we’re headed for a bad place when it comes to rising global warming,” Cook told the Guardian. “What this research shows is that, until now, we’ve had emergency brakes.”
An accidental temperature buffer may not stay in place forever. Although atmospheric dust concentrations have been rising since the pre-industrial era, they peaked in the 1980s and have declined since then. If this decline continues or intensifies, warming could catch up with us even more quickly – a troubling prospect in the future Already broke the recordhot reality.