DRI expert offers new theory on climate

A Desert Research Institute scientist is adding to the findings that humans are affecting global climate change.

A report released last week in the weekly journal Proceedings of the National Academy of Sciences and co-written by DRI research professor Joseph McConnell says that human deforestation and overgrazing in South America have led to greater amounts of dust in the atmosphere.

That dust has contributed to the trapping of greenhouse gases, which has increased the temperature around Antarctica, the report says.

McConnell and a team of researchers, including others from the Desert Research Institute, examined a 394-feet-long ice core sample from Antarctica that dated from 1832 to 1991.

The sample showed that dust deposited from the air more than doubled during the 20th century. “It quite surprised us because it showed pretty dramatic increases during the 20th century,” McConnell said.

The scientist said he wasn’t interested in the data until he matched it with other available data sets. “I plotted it up and realized that it paralleled air temperature increases,” McConnell said.

The level of atmospheric dust closely matched air temperature increases of about 1 degree Celsius in the Southern Hemisphere and southern South America during the same period.

“We were a little surprised to see it so closely linked, but it is,” McConnell said. “To my knowledge, it’s the first record that links increases in climate warming and atmospheric dust.”

Records also show that high dust levels in the Antarctic Peninsula corresponded to warm and dry conditions during spring and summer in Patagonia and elsewhere in southern South America.

During the past 75 years, Argentina has lost about 66 percent of its forested lands, according to the report.

Patagonia, a massive steppe plains region in southern Argentina, is home to sheep, cattle and goat farming.

The overgrazing of the land in Patagonia has caused “severe land degradation and desertification throughout the region,” the report says.

More than 30 percent of Patagonia’s 350,000-square-mile surface has experienced desertification in severe to very severe stages, the report says.

Increased dust in the atmosphere has traditionally been linked to decreased global air temperatures in other studies because the dust often reflects sunlight, McConnell said.

His study was funded by the Fulbright Program, the U.S. National Science Foundation and the Instituto Antárctico Argentino. The research was the first to link the dust to increases in temperature, McConnell said.

The increased dust may also be affecting the nearby biological activity.

Phytoplankton feed on the iron deposited by the atmospheric dust on the ocean surface, which affects all ocean life.

Scientists have attributed relatively high surface water chlorophyll near James Ross Island in Antarctica to Patagonian dust composition, according to the report.

McConnell said it is unknown how much the atmospheric dust has contributed to warming on the Antarctic Peninsula.