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ASU professor helps lead world efforts to track extreme weather

December 13, 2016

Randy Cerveny, professor in the School of Geographical Sciences and Urban Planning, says records can teach us about our planet

It might seem hard to believe, but there recently was an ocean wave as tall as a six-story building in the north Atlantic. 

The World Meteorological Organization on Tuesday classified the 2013 rise between Iceland and the British Isles as the largest wave ever monitored by an ocean buoy, measuring taller than 62 feet (19 meters).

Randy Cerveny

It’s the latest extreme record verified by the Geneva-based United Nations agency that keeps track of world’s weather, climate and water, which Arizona State University professor Randy Cerveny helps run by leading the WMO’s confirmation group and curating the events it substantiates at ASU.

Among the oddities in the archives that Cerveny maintains: a 2.25-pound hail stone that fell in Bangladesh in 1986; and 1.25 inches of rain dropping in one minute in Maryland in 1956.  

Cerveny, a climatologist who teaches in the School of Geographical Sciences and Urban Planning, says it can take anywhere from a few months to a few years to verify an extreme event and that a lot can be learned from these records. He discusses his work with ASU Now:

Question: Why keep weather records?

Answer: First, by knowing what the extremes are we can gain a better idea of how our climate is changing over time.

But there are other reasons, such as engineering or medical concerns. Engineers need to know what the absolute strongest winds are, for example, in order to properly design buildings. Doctors need to know how hot an area can actually get to be better prepared for medical emergencies.

On a less serious note, I’ve been told some of this information has even helped settle some serious bar bets and bragging rights.

Q: What can these records tell us?

A: Basically, they give us a snapshot of how wild and violent our world can be. Extremes are the worst of the worst — the hottest, coldest, windiest and so on. So knowing them tells us how bad (or how good) the weather on our planet can be.

Q: Is there anything we can learn from the records to help us understand the dynamics of our planet?

A: Absolutely.

Knowing more about the absolute limits of our weather better informs us about all types of weather up to those limits.

In our recent evaluation of the longest-distance and -duration lightning flashes, we realized that we would have to literally rewrite one of our fundamental definitions of lightning.

The current professional definition, which dates back to the 1980s, states that lightning is an event that “lasts less than a second.” But with improved technology, we now know that lightning, in rare circumstances, can actually last many seconds.

Our investigation of lightning extremes helped to confirm that fact.

Q: From your perspective, what is among the most interesting records?

A: Probably the most interesting has been the world’s hottest temperature, as there has been a huge amount of interest in that record, and it has been cited in most encyclopedias and textbooks for more than a century. The current record for hottest temperature is 134 F, recorded on July 10, 1913, in Furnace Creek, Death Valley, California.

It also has been a very contentious record, with vocal supporters and critics around the globe.

Interestingly, our initial investigation in 2012 of what was then the record involved a life-threatening situation. Indeed, when we first discounted the original hottest temperature of 136 F back in 1922 Libya, one of our members, a Libyan meteorologist, was actually in Tripoli as the revolution in 2011 occurred. He managed to escape to the rebel side with his family while, he said, gunfire was occurring around them.

Q: What is among the most offbeat records?

A: Probably our recent determination of the longest-distance and longest-duration lightning flashes (199.5 miles in Oklahoma and 7.74 seconds in southern France, respectively).

The high-quality engineering work to determine those records is really quite impressive.

Everybody probably has experienced the static on the radio when lightning occurs. We used that idea of radio waves to accurately position exactly where and when a lightning flash starts and stops, employing a large network of very sensitive and complex radio sensors over an area.

It was a clever use of existing technology to gain clarity of a natural phenomenon.

Q: Why are we fascinated by weather extremes?

A: I think that our culture has always tended to promote the biggest, the highest, the strongest, etc., and that interest has led to great interest in the extremes of weather.

Books from organizations such as the "Guinness Book of World Records" have always captured the interest of the public.

Having been fascinated by those type of books as I was growing up, I find it interesting — and a bit humbling — to now be one of the group of experts that Guinness now calls to verify its own weather records.

Q: Will we see more records fall in the future?

A: Absolutely. Our climate has changed, is changing and will continue to change, and as part of that, the extremes of climate also will continue to change.

With the creation of the WMO’s Archive of Weather and Climate Extremes under the authority of the United Nations (and hosted through Arizona State University), we will continue to officially monitor and verify those extremes.

Top photo by Ove Tøpfer/

Director , Media Relations and Strategic Communications


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ASU archaeologist goes 'Jeep' into Mongolia

December 13, 2016

Research in the relatively unstudied region could have a big impact on our knowledge of human origins

When archaeologist Charles Perreault traveled to Mongolia for some investigative fieldwork, he didn’t bring the typical tool set of shovels and spades. Instead, he brought two all-terrain Jeeps, beginning a new project that will improve our knowledge of the early hominin groups that occupied northeast Asia, including ancient Homo sapiens, Neanderthals and a newly discovered species called Denisovans.

As an assistant professor at Arizona State University’s School of Human Evolution and Social Change, Perreault studies cultural evolution, or the way that people share cultural information like technology through social interaction. He is also an evolutionary anthropologist, meaning he looks at archaeological evidence to research the ancestors of modern humans.

Perreault did his master’s thesis on basketry technology in Peru, but as he worked to finish his graduate program, he often found himself being driven by questions about human evolution. Finding the answers to those questions soon required him to start looking beyond more recent archeological sites in the Americas to older, more foundational sites in Eurasia.

In graduate school, Perreault worked on the riddle of why humans first decided to live in the high-altitude environment of Tibet. But it was Mongolia that truly began to draw Perreault’s interest, particularly after archaeologists found millennia-old hominin bone fragments in a cave near the country’s shared border with Russia in 2008.

A little revolution

The Russian cave finding that inspired Perreault was significant for several reasons — first, because some bone fragments within were identified as belonging to Neanderthals. Before then, Perreault explained, scientists believed that Neanderthals were mostly limited to Western Europe. Suddenly, their range had doubled.

Second, analysis of part of a pinky bone from the cave revealed the existence of an entirely new hominin species, dubbed Denisovans after the cave where scientists found the fragment. These Denisovans — cousins of Neanderthals and modern humans — were the first species to ever be identified on ancient DNA alone.

Lastly, further analysis of other ancient bones from the site suggested that Neanderthals had interbred with Denisovans at some point in history. And by comparing the Neanderthal and Denisovan DNA samples to modern human DNA samples, scientists found that people today have genes from both groups in their DNA. This means that Neanderthals and Denisovans also interbred with ancient Homo sapiens — a finding that sheds new light on the interactions between hominin groups thousands of years ago.

photo of a cave surveyed by Dr. Perreault in northern Mongolia

One of the rock shelters surveyed by ASU assistant professor Charles Perreault in northern Mongolia. Photo by Perreault


“It led to a little revolution in our understanding of human evolution outside of Africa,” Perreault said. ­“As modern humans expanded their territories, they weren’t just colonizing some empty world. They were entering and colonizing areas populated with other hominin species … maybe with different language, clothing and culture. That’s crazy when you think about it.”

It was just crazy enough, in fact, to inspire Perreault to begin his own journey across the globe to Mongolia. Part of the appeal, of course, was the chance to do archaeology in the region of the groundbreaking Denisovan find — but the undertaking was not without its challenges.

“We have to build everything from the foundation,” Perreault said. “We know little about that part of the world, so the effort is just to get a basic understanding of [questions like], ‘When did people arrive in that region?’”

Research, risks and rocky roads

By summer 2016, Perreault found himself in the Darkhad Valley of northern Mongolia, but before he could even think about excavating, he had to first find potential archaeological sites. He and his team of two drivers, two archaeologists from the Mongolian Institute of Archaeology and two American archaeologists formed an off-road caravan. Every day, they drove for eight to 10 hours, crossing miles of mountains and rivers — hence the all-terrain Jeeps.

“The goal of the trip was to find prospective sites to go back to and do excavation. So this time around, it was just traveling, trying to find caves or rock shelters,” Perreault said. “We looked at the caves to see if there were any cultural artifacts on the surface, but we didn’t dig a single hole.”

photo of Dr. Perreault exploring a rockshelter in the southern part of the Darkhad Valley.

Perreault explores a rock shelter in the southern part of the Darkhad Valley. Photo by David B. Madsen

With a daunting amount of ground to cover and limited time to cover it, the team knew they couldn’t afford to just throw darts at a map. Instead, Perreault tried to gather as much information as possible in advance. By looking at geological maps, for example, he was able to note the locations of limestone outcrops, an ideal rock type for cave formation. He also reviewed reports and papers from other archaeology projects near Mongolia to see what others had found. He even tracked down and talked to another archaeologist who had once driven through the region 10 years prior and reported seeing a few rock shelters.

“The good type of rock is there, people have seen rock shelters, Mongolia has a deep archaeological record, and very important sites have been found in similar geological settings in Russia,” Perreault said. “Taken together, all these things suggest to us that this is an area that has some potential.”

Of course, no amount of advance research guarantees success in the field.

“It’s possible we could have gone there and found nothing,” he said. “But it went very well; it went better than I expected.”

In fact, by the end of the three weeks, Perreault’s team had found about a dozen rock shelters.

Now that the first step is done, he plans to do some test excavations next summer in the three or four more promising caves. If all goes well, a bigger team of workers and researchers will come in to do a full excavation — and with the possibility of rock-hard permafrost to dig through, that looks to be no small feat.

Photo of Dr. Perreault collecting data in front of a rock shelter in Mongolia

Perreault is shown collecting data in front of a rock shelter in Mongolia. Photo by David B Madsen

Perreault explained that in the initial stages of an archaeological project, much of the energy is devoted to excavation, with a preliminary analysis of artifacts sometimes conducted in the field. For example, students often help by cleaning and cataloging artifacts on site.

Once the team has excavated a greater portion of the site, which could be years later, the primary investigator will do a deeper analysis of the uncovered artifacts.

Perreault plans to be involved both in the excavation and the artifact analysis in later stages of the project. He is excited for the new discoveries the sites might yield. Though these archaeological ventures tend to be long affairs, he welcomes the challenge.

“Hopefully, there’s enough stuff there to keep me busy for the next 10 years or so,” he said.

Mikala Kass

Communications Specialist , ASU Knowledge Enterprise