Study: Human activity more deadly to species than natural climate change

October 22, 2015

ASU researcher, team examine fossil evidence from Caribbean sinkhole

An underwater fossil hoard discovered in the Caribbean has revealed that people have done more to deplete animal species than the shift of the last ice age.

A study co-authored by Janet Franklin, Regents’ Professor in the School of Geographical Sciences and Urban Planning at Arizona State University, and published this week in the Proceedings of the National Academy of Sciences deals with the relative impacts of climate change and direct human activity on animal-species extinction.

Sawmill Sink, a flooded sinkhole cave or “blue hole” on Abaco Island in the Bahamas, yielded 95 species of ice-age vertebrates, the most ever found on any Caribbean island. Thirty-nine of those species no longer exist on Abaco Island.

The warmer, wetter climate and rising sea levels that occurred from 15,000 to 9,000 years ago during the transition from the last ice age to the present climate probably led to the disappearance on Abaco of at least 17 species of birds — species characteristic of open habitats like pine woodlands and grasslands found on cooler, drier, larger ice-age Bahamian islands.

Although the 17 species of birds didn’t survive the ice age, 22 species of reptiles, birds and mammals did.

But they didn’t survive human beings. When people appeared on the island about 1,000 years ago and used fire to clear land for farming, those 22 species disappeared. Island species are particularly vulnerable to habitat loss because of the limited land area.

A woman sits on a wooden platform over a Caribbean sinkhole

ASU Regents’ Professor Janet Franklin sits at
Sawmill Sink, where fossils of 95 ice-age
species were found. Top: The Bahama or
rose-throated parrot, which has lived on
Abaco since the last ice age.

Photos from Janet Franklin

Franklin was surprised how many species — especially of birds — stuck around the island even as the climate warmed and the islands shrank at the end of the ice age.

“We expected that there would be cooler-climate, open-country birds there in the last ice age that subsequently disappeared (went extinct or moved north), and we found that,” she said. “So that is a really cool finding, but we predicted it.

“It was dismaying to also find that, of those many species that are so adaptable they can live in the glacial or interglacial Bahamas, a whole bunch of them could not stand the pressures that accompanied people who arrived 1,000 years ago — namely the big changes in habitat that happen when people burn to clear land for farming.”

One of the biggest challenges is the speed of human-driven change. Natural climate change, such as the Earth warming from a passing ice age, takes thousands of years — a span of time that allows species to adapt, Franklin said.

“But human-caused climate change, caused by fossil-fuel burning and other greenhouse gasses emissions, only started in the 19th century and is really fast compared to natural climate change,” she said. “Species do not have a thousand years, or 10 or 100,000 years, to adjust, migrate, evolve.

“The same temperature changes are happening in 50 to 100 years, and on a planet where land is fragmented by farms, cities, etc. This makes it difficult for wildlife to adjust by migrating. How do they get there? Unless they can fly. Habitat connectivity is important in conservation planning.”

Fossil bones from the extinct green sea turtle (Chelonia mydas) and shells with bite marks from the extinct Cuban crocodile, found by local resident Perry Maillis at one of the fossil sites on Abaco Island in the Bahamas.

Janet Franklin/ASU

The scientific value of the fossils found in the caves has contributed directly to the establishment of a new protected area. South Abaco Blue Holes National Park now protects the system of flooded caves where many fossils have been found, including Sawmill Sink. The area supports pine woodland rich in native flora and fauna. Here, David Steadman and Julie Ripplinger are shown birdwatching.

Janet Franklin/ASU

A tortoise shell in remarkable condition is recovered from Sawmill Sink, pictured with project lead author Dr. David Steadman of the University of Florida and collaborator Nancy Albury of the National Museum of the Bahamas. Steadman is an expert on bird fossils; Albury is a vertebrate paleontologist.

Janet Franklin/ASU

The hairy woodpecker (Picoides villosus) has now been indentified from fossils as occuring in the Bahamas at least since the last ice age.

Janet Franklin/ASU

The fossil evidence from the Caribbean sinkhole the team studied shows how much more of an impact human presence had in a vastly shorter time.

“The … arrival of people probably depleted more animal populations than the dramatic physical and biological changes associated with the (ice age),” the paper’s authors wrote. They concluded that, even though human-caused climate change in the 21st century is much more rapid than natural glacial-interglacial cycles, “[f]or the species that remain, we believe that direct human activity threatens their immediate future more than climate change.”

Franklin’s research is focused on the impacts of human-caused landscape change, like forestry and urbanization, on the environment.

“Planning for biodiversity conservation should consider all ways humans use the land, in addition to human-caused climate change,” she said. “That is why it is so gratifying that the Bahamas has just established several new marine and land protected areas, including a national park that protects the caves where the fossils were found because of their scientific value.”

The Sawmill Sink team included:

Lead author Dr. David Steadman, University of Florida, an expert on bird fossils. He assembled the group of experts needed to correctly identify almost 100 species from tiny bones.
Brian Kakuk, another coauthor and expert cave diver who recovered most of the fossils. “Without his unique skills and fearlessness, we would not have such an amazing array of fossils to study,” Franklin said.
Nancy Albury, vertebrate paleontologist with the National Museum of the Bahamas who has been working at the site for more than 10 years and facilitated the research in the Bahamas.

The Sawmill Sink project was sponsored by the National Science Foundation. NSF support also will allow the team to return to the Bahamas later this year to explore island caves, further researching how human presence affected survival of species.

The School of Geographical Sciences and Urban Planning is a unit of the ASU College of Liberal Arts and Sciences.

Scott Seckel

Reporter, ASU News

Life doesn't stop for ASU online students who want to better themselves

An ASU student interacting with an online course

Editor's note: This feature is part of a series profiling different slices of ASU's diverse population. Find more stories here.Students finishing a college career later in life have a lot to contend with. Many have full-time jobs. Others have family obligations. ASU Online student Tony Bothwell has to juggle both, and also watch out for the occasional freeze ray attack.Bothwell spends part of his...

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Life doesn't stop for ASU online students who want to better themselves

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ASU online students enhancing their education on their own timetable

Editor's note: This feature is part of a series profiling different slices of ASU's diverse population. Find more stories here.

Students finishing a college career later in life have a lot to contend with. Many have full-time jobs. Others have family obligations.

ASU Online student Tony Bothwell has to juggle both, and also watch out for the occasional freeze ray attack.

Bothwell spends part of his days keeping an eye on his 3-year-old son, Lucas, whom he describes as “a fussy toddler,” while his wife is at work. That has led to something of a non-traditional soundtrack to his educational career.

“This semester so far, statistics and (web site design) have been to the tune of ‘Hotel Transylvania’ and ‘Alvin and the Chipmunks’ …” Bothwell said, referencing the popular children’s films. “Psychology 101 and graphic communications were both Spring A session, I remember those specifically always had either ‘Frozen’ or ‘Despicable Me’ in the background.”

Hence the freeze rays A photo of Felonius Gru, from the Universal Pictures Movie Despicable Me In the Universal Pictures movie "Despicable Me," the freeze ray is the signature weapon of a character named Felonius Gru. It causes the people it is used upon to be temporarily frozen in their tracks. , which, during imagination time, Lucas will sometimes employ upon his unsuspecting father, causing a delay in studying.

“It’s worked out though,” Bothwell said with a laugh.

It continues to work out for Bothwell.

He’s a senior solution developer for Kaiser Permanente, a health maintenance organization, in Sacramento, California. At age 39 he decided to complete his undergraduate work. Now he is the equivalent of a junior, earning his degree in graphic information technology online.

A picture of Tony Bothwell and his son, Lucas, in their California home

Tony Bothwell with his son,
Lucas.

Photo courtesy Tony Bothwell

Bothwell is very successful — he writes highly valued automation software for Kaiser — but the lack of a bachelor’s degree has put a ceiling on his career trajectory.

“Not having a degree is literally the stopping point,” he said. “That will be a roadblock everywhere I turn from this point.”

In a couple of semesters that roadblock will be cleared for Bothwell.

ASU Online clears many roadblocks for its students. The program now has more than 19,000 students enrolled, and offers more than 100 degreesThe top degrees in the ASU Online program are psychology, criminal justice, electrical engineering, organizational leadership and health sciences..

"As a university, we're committed to helping learners everywhere achieve a quality education, said Phil Regier, University Dean for Education Initiatives at ASU and CEO of EdPlus. "We've designed our digitally-enabled courses and degree programs with the student experience in mind, ensuring that students have the tools they need to succeed from anywhere in the world.”

Those digitally-enabled courses place reading, videos, tutorials and coursework online in an easily accessible environment for students. Assignments typically are due once per week, giving students in various places — and timezones — plenty of time to complete each task no matter their personal schedules.

The flexibility is key. For Bothwell it means being able to work on his couch with his son nearby.

For Mi Young Lee, the flexibility allows her to balance the 12-hour shifts that come with a busy nursing job on a military base. She logs into ASU Online from Seoul, Korea, 16 hours ahead of Bothwell on the clock.

Lee, who is 38, is a nurse at the Brian Allgood Amry Community Hospital on the Yongsan Garrison, an American military installationBecause of its location, the hospital in which she works is considered a combat hospital. Should shots ever be fired on the Korean peninsula, it would be the main hospital for U.S. troops..

She is Korean and earned her nursing degree in her home country. But her goal is to become a nurse practitioner.

A photograph of Mi Young Lee, at the hopsital in which she works, in Seoul, Korea.

For Mi Young Lee, the flexibility of online classes allows her to balance the 12-hour shifts that come with a busy nursing job on a military base. Photo courtesy Mi Young Lee.

“We don’t have that program in Korea,” she said. As a result, her degree won’t get her into American nurse practitioner programs.

“This is my stepping stone so I can get ready and prepare myself.”

Because of the varied hours of a nurse, ASU Online allows her to work when she is free to do so. And Lee is not limiting herself to nursing classes. While enrolled at ASU, she is challenging herself to take full advantage of the breadth of offerings online, including a class she took this summer on world faiths.

“It helps me open my eyes to understand different religions,” said Lee, who is Buddhist.

A typical ASU Online student — if there is such thing — is not as physically far away as Lee. Forty-six percent of ASU Online students are in Arizona; another 25 percent live in California. There are more women than men enrolled (a roughly 60/40 split) and about a quarter are working on graduate degrees.

Jerome Tennille plans to become one of them — right after he finishes his undergraduate degree this fall.

For Tennille, a Navy veteran and ultra marathoner who usually starts his day with a 5 a.m. run, ASU Online allows him the flexibility to get his education while serving a community for whom he has a passion.

He’s in line for a degree in operations management from ASU Online, and he’s already using the skills from his virtual classroom in his day job: coordinating volunteer efforts for a Washington, D.C.-based organization called TAPS, which helps what they call military survivors — the loved ones and friends of service members who have died while serving in the military.

“You can be a battle buddy, you can be a sibling, a fiancé, a spouse …” Tennille, 29, said. “We provide the services beyond the standard issuance of life insurance that a family might get from the government. We provide the emotional service.”

A draining job, to be sure.

But after his day at work, he digs into his class assignments — this semester he’s taking a quality assurance class and working on his senior project — and sustains his focus for another couple of hours.

Jerome Tennille is a Navy veteran and ultra marathoner who usually starts his day with a 5 a.m. run. ASU Online allows him the flexibility to get his education while serving a community for whom he has a passion. Photo courtesy Jerome Tennile.

He admits that that can be tough, but he knows something about tough. Tennille postponed his studies to join the Navy three years after 9/11, at age 19.

After eight years in the military, including two deployments to the Persian Gulf aboard the USS Iwo Jima, Tennille turned, as many veterans do, to ASU for his college education.

“I wanted to be a part of a school that valued veterans …” Tennille said. “They embrace us, and I want to be a part of a school that would understand the culture and embrace that and provide the education that I wanted.”