Studying the effects of dust and drought on climate change – NAU

Atmospheric dust plays a key role in the Earth’s climate system. Although it can have a positive impact, such as fertilizing the floorsdust can also negatively impact our planet’s ecosystems, affecting everything from climate to global warming.

For example, in the Four Corners region, which includes parts of Arizona, Colorado, Utah and New Mexico, millions of people depend on water from the snowfall of the San Juan Mountains. which melts and eventually flows downstream into the Colorado River. Dust from the atmosphere falls on the snow, darkens it and accelerates snowmelt. As the snow melts faster, it evaporates faster, impacting the water supply of an area already affected by extreme drought.

Associate Professor Nick McKay and his team of NAU paleoclimatologists School of Earth and Sustainability have been studying dust from this high altitude region, which is particularly vulnerable to climate change, for several years. Funded by a private donation from Bob and Judi Braudy in 2016, they collaborated with scientists from Cornell University to study the effects of dust and drought during Phase I of “The Drought-Dust Nexus in the Four Corners Region and Impacts on Society”. Now, with additional funding from the same donors, the collaborators will continue their research for another five years.

“It’s hard to overstate the impact of the Braudys’ donation,” McKay said. “It gave us the freedom to pursue cutting-edge, high-risk science that would have been difficult to sustain with traditional mechanisms, while supporting three graduate students and several other undergraduate students. It helped launch a new generation of scientists here at NAU. Toby and I were thrilled that the Braudys were interested in funding more research in a new and exciting direction.

The Cornell team is led by an associate professor and climatologist Toby Ault and includes a research associate Carlos Carrillo. In addition to Principal Investigator (PI) McKay, the NAU team includes an Assistant Research Professor Cody Rouson, Stephanie Arcusa-who led NAU’s efforts on Phase I of the project, has completed his Ph.D. in December 2020 and is now a postdoctoral researcher at Arizona State University – and Ph.D. student Frank Telles, who joined McKay’s team for Phase II. Telles is an Indigenous student from the Chiricahua Apache Nation of New Mexico. In addition to his passion for climate science, Telles is committed to research that will ultimately help the indigenous peoples of the region, including the Navajo, Hopi, Ute and Zuni tribes.

During Phase I, collaborators made important breakthroughs, uncovering new dimensions of dust, drought, land use and climate change. At Cornell, Ault and Carrillo introduced new methodologies to simulate the large-scale effects of drought and dust in the region.

At NAU, McKay and Arcusa developed new paleoclimate records of dust deposition over the past 15,000 years using lake sediments and compared them to drought records from tree rings and other natural records.

“The big surprise of Steph’s work in Phase I is that the natural relationship between dust and dryness is much more subtle than we had assumed,” McKay said.

“From the lake records we see that the southwest is dustier today than it has been for the past 11,000 years with a dust peak in the mid-1800s, but this is not correlated to the drought records,” Arcusa said.

The NAU team has published its first results in the peer-reviewed journal The Holocene, where they noted that “our results demonstrate that although the Colorado Plateau is naturally dust-prone, drought is a secondary factor in dust accumulation in the mountains. This suggests that land use management decisions aimed at reducing land disturbance can mitigate future dust accumulation, despite projected increases in regional aridity.

The scientists found that the dust accumulation was strongly influenced by the presence of disturbing human activities and land use such as livestock grazing, which the team hypothesizes makes emissions dust more sensitive to droughts.

The team used their unanswered questions from the first phase to develop research goals for the second phase, during which they will deploy unmanned aircraft being designed at Cornell to hunt dust storms in the atmosphere. over northeast Arizona and the Four Corners region and collect dust samples and data for research. They will also use weather balloons equipped with low-cost sensors to track the flow of dust from the earth’s surface into the atmosphere.

McKay and his team, all part of his Palaeoclimatic dynamics laboratory, use natural records of past climate variability to inform our understanding of climate dynamics. They study natural climate variability in locations ranging from the tropics to the Arctic, on time scales ranging from years to millennia, and on spatial scales ranging from hemispheres to meters.

Much of my research is on very large spatial scales, so I enjoy working locally and addressing issues that directly affect northern Arizona,” McKay said. “Dust has many impacts on society, impacting human health and safety, snowpack and water resources, agriculture and the tourism industry, but we still have a lot to learn about how the climate affects dust, how dust moves through the atmosphere, and how to predict when and where dust storms will occur.

Teresa H. Sadler