The University of Alabama

Caving for Climate


Niue Island as shown by Google Earth

Niue Island as shown by Google Earth

Dr. Paul Aharon

Dr. Paul Aharon

A 10,000-year-old weather report? Come on. That’s going a tad deep into the archives, isn’t it? Yet, that’s the untold story that caves on a South Pacific island are expected to reveal to a group of University of Alabama geologists beginning this week.

Led by Dr. Paul Aharon and funded by the National Science Foundation, the UA scientists (including Dr. W. Joe Lambert and doctoral student Hillary Sletten) will spend July 8-Aug. 5 on the island of Niue (pronounced new-ay). The stalagmites in the island’s caves contain about 10,000 years of rainfall records driven by El-Niño that can be revealed through laboratory analysis. The UA group is looking to verify the impact the El-Niño/La Niña patterns have had historically on climate change. This could provide the scientists with more insight as to how our global weather patterns may continue changing.

Group members will periodically blog about the research adventure during the next month.

The Moment of Truth – August 8, 2011

Hillary Sletten

Annual layers are visible in the stalagmites from Ulupaka Cave, (Photo by Hillary Sletten)

Dr. Joe Lambert looks on as Henry Skorek splits a piece of a stalagmite. (Photo by Hillary Sletten)

I am holding my breath as I stand next to island craftsman Henry Skorek. He is leaning low and carefully, guiding one of our stalagmites through his tile saw, diligently slicing the first of our samples in half. The engine starts whining – it is a much larger load than what it is used to handling. This will be the revealing moment. Will the sample show distinct annual growth layers and be unaltered? Will there be a high amount of void space in the calcite that could debunk our data? Has all of our work been for nothing?

Henry nears the end of the first slice and finally pulls the pieces away from the blade, and there, to our sheer joy and utter amazement, are thin, clearly visible layers … each holding the information we will need to construct one of the longest rainfall records for this part of the world.

Hillary Sletten holds a piece of a stalagmite cut in half by Henry Skorek. (Photo by Joe Lambert)

I jump from the ground and give Henry a hug. It’s funny how things work out, but out of all the people, this Polish expatriate was the only person on Niue who was able to tell us we had pulled the right samples out of the cave. The key was his wet saw with a diamond tipped blade … and his knack for making a good cup of Polish coffee.


It takes two mornings to get through all of the samples, and when things are finally done, we make arrangements for Henry to also construct wood boxes and shipping crates. Now commences the task of going through the Department of Agriculture, Forestry and Fisheries, as well as the Customs Department, to get the proper paperwork for our precious cargo … an interesting chore in a remote and foreign country.

While this is in the works, Joe and I busy ourselves with one last visit to Ulupaka Cave to conclude our dripwater sampling and mapping. We also work on preparing sampling manuals for the meteorological staff who will be sampling on their own every month for the next year.

Dr. Joe Lambert hands out rulers from The University of Alabama Department of Geological Sciences to staff and students at the Niue High School . (Photo by Adorra Misikea)

The following day, we had the opportunity to share with high-school students what we do as geologists and why our research on Niue is important. After we arrive at the school and set up our presentation, a crowd of shy, smiling 17-year-olds stumble into the classroom. They all sit in the back row, eyeing me and Joe in our matching labs shirts. Maybe we looked somewhat familiar to them. Joe and I had been interviewed the week before by TV Niue Broadcasting News for a segment airing on the evening news. The news only runs twice a week, so it’s viewed by the majority of the islanders.

Not too long into our presentation I ask the students how many of them have been to a cave on the island, and just as we might have guessed, only two students raise their hands. So, this turns into an even greater opportunity to share with them the amazing and important resources they have right below their feet.

Hillary Sletten and Dr. Joe Lambert bid farewell to Niue. (Photo by the Niue Honey Man)

The week wraps up, and not long after I get my last photos on Niue, I am holding my breath once again, but this time in the New Zealand Biosecurity Customs queue. We are patiently waiting to see if all of our samples will be let into the country. Our turn finally comes around, and, again, I can exhale with relief. We are through. Last stop – the USA!

The journey has been enlightening, educational and productive. We came with a plan, and despite several challenges along the way, we mastered the plan. This work could not have been possible without the help of numerous people – both in the States and on Niue – and to all of them I am extremely grateful. I am now at the beginning of a whole new journey as I venture into a different type of unknown … the process of earning a Ph.D.

Drip, Drip, Click, Click – July 29, 2011

Hillary Sletten

Stalactites on the ceiling of Ulupaka Cave. (Photo by Hillary Sletten)

Hillary Sletten assisting with cave measurements at Ulupaka Cave. (Photo by Mellisa Douglas)

I lean back with my head crooked up, snapping photos of different cave formations at Ulupaka Cave.

There are too many to humanly count or take pictures of; however, I can’t help but try to capture a few tiny pieces of this fascinating underground world through my lens and selective eye.

I try to take pictures of things that make me ask questions. For instance, why would this stalactite grow sideways when all the other ones around it are being good little soldiers and dripping down like the rest? Is it even considered a stalactite?

Did it skip school one day and miss the lesson on how to conform to gravity? These are the types of things reeling through my head as I click, step and wiggle through the dark, somewhat slippery, passageways.

As I make my way toward the cave’s center, I hear the voice of Joe, along with those of Adorra Misikea and Mellisa Douglas, staff members from the meteorological station. This is our third visit to the cave since our decision to use Ulupaka for our study.

After many days of investigations and negotiations, we have gained permission from the cave’s owners to conduct our work here. We are hopeful the cave has been a vigilant recorder of changes in rainfall amount through time. We will know when we cut open the two stalagmites we have collected from Ulupaka.

Hillary Sletten chisels away at the base of a stalagmite in Ulupaka Cave. (Photo by Joe Lambert)

I round a corner and see the group nestled in the room where the majority of our work is taking place. They are standing near the location where, last week – with chisel, hammer and muscle – we removed the second of two stalagmites.

This was a fairly easy task with multiple hands helping. We removed one stalagmite about 1.5 m tall at this location, and 2 m away we collected another one about 0.75 m tall. Collecting two samples will allow us to do a comparison study of two different formations in the near-same environment.

As I approach the group, they are discussing how to install one of our dripwater collection stations. Joe and I have worked on multiple designs for this station, and we think we have finally found one that works. I look over at the first station, which is already assembled, and see water dripping into our collection bag. We will sample this water in a few hours once we have enough water for our bottle set.

Using these water samples, we will run chemical analyses at The University of Alabama Stable Isotope Laboratory to calculate the ratios of carbon, hydrogen and oxygen. We will then correlate these values to the ratios of carbon and oxygen in the powdered samples of the stalagmites. This is one of a handful of techniques we use to link rainwater to the stalagmites.

Dr. Joe Lambert, Adorra Misikea, and Mellisa Douglas measuring the pH of the dripwater at Ulupaka Cave. (Photo by Hillary Sletten)

A few final decisions are made, and plans for the drip water collection stations are complete. We are onto a quick lunch in the “master bedroom” – the name Adorra has given the biggest chamber in the cave. After lunch, we conduct some simple measurements of the cave dimensions. No one has mapped this cave before, so we are attempting to get rough estimates of the size of the rooms and passageways so that we can sketch maps to better understand the cave system.

As I pull the measuring tape across one of Ulupaka’s many rooms, I shine my light into a crevasse that has never seen daylight. I never cease to be amazed at how many different ways we are exploring Niue.

With a few hours of mapping under our belts, we return once again to the “master bedroom” where Joe and I oversee Adorra and Melissa as they sample and distribute the dripwater from the first station into the bottle set.

For the next year, they will conduct monthly sampling of the dripwater for which they will also document parameters such as the pH of the water, water temperature and air temperature. They will ship us dripwater samples, along with rainwater samples from the meteorological station, every three months. Adorra and Mellisa have been quick understudies to our field methods, and we are very grateful for their partnership.

Before I know it, we are stepping out of Ulupaka back into the afternoon sun and breeze. It is such an instant relief to feel the wind pass over me. Palm and coconut trees scattered among the rocky bush welcome us with their swaying leaves. I lean back, snap a photo, and hold onto the moment.

Life on ‘The Rock’ – July 25, 2011

Hillary Sletten

Sunset from Alofi, Niue. (Photo by Hillary Sletten)

Sunset from Alofi, Niue. (Photo by Hillary Sletten)



Large spiders are scary surprises when walking in the bush. From tip to tip, this one found in the Huvalu Forest Conservation Area measured about 10 cm (4 inches). (Photo by Joe Lambert.)

In between our investigating, planning and field work, there have been opportunities to experience the beauty and culture of Niue. We are surrounded by these intertwined aspects of the island on a daily basis, both openly and subtly. I need not step but a foot out the door of our bungalow and see the lush foliage and blue sky to know I am in a special place.

Within a short walk or drive, my eyes can rest easy on a sunset over the South Pacific; my ears can hear the crashing surf, the rustle of palm leaves from the constant breeze, and the cries of roosters in the distance. When I walk into the bush I can smell heated earth; I can see creatures that make my breath stop short.

By many western standards, life on “The Rock” is simple. It is a country with 12 main villages, connected by narrow two lane roads, a lot of bush and some smaller dwelling areas in between. Homes are no larger than necessary, and luxuries are rare. There are no such things as master bedrooms with private bathrooms, billiard rooms tucked in the basement, or garages full of unused items. Families have a washing machine, but no dryer – clothes are hung on the line. Cars are not thought of as items to routinely replace when you get tired of the leather seats; cars get you from point A to point B. When you need to talk to someone, you set a time and go see them in person instead of emailing or texting. The list goes on and on.

In general, family is a strong value here. One way this is seen is in the division of land, in which every Niuean is given a portion of family land to farm and build on. This has instilled a culture where all of the family members living on the island know how to plant, harvest and eat off the land to supplement what they buy in the store. Being connected to the Earth in these ways, along with education, has given rise to better awareness about weather and global climate.

Dr. Paul Aharon and Hillary Sletten beside a billboard in front of the Niue Meteorological Service station. (Photo by Joe Lambert)

Concerns about climate change impacts were specifically amped in 2004 when a Category 5 tropical cyclone called Heta hit the western coast of Niue. This event brought storm surges over 40 meters high, destroying most of the capital city of Alofi and causing over NZ$85 million (in New Zealand currency — about $73.6 in today’s American dollars) in damage. Islanders had never experienced such a severe storm. Although the people recovered, a few signs of Heta are still visible today. Many homes damaged from the winds and surge, for instance, are still amidst villages. Cyclone Heta has also caused residents to keep a closer eye on signs of climate change and their effects on the island. The Niue Meteorological Service station now has a program dedicated to climate change with staff that attends meetings throughout the South Pacific Islands related to climate change and hazard preparedness.

Last Saturday, Joe and I got the chance to experience a different type of climate. We were able to witness how the Niueans celebrate and entertain by attending the Alofi South Show Day. In comparison, this might equate to a town festival or county fair back home in the States. Each month a different village hosts a show day, and a good portion of the island attends each one. Festivities kicked off at about 7 a.m. Booths with traditional foods, crafts and fundraising games circled the central yard at the primary school. The highlight was the musical and dance performances given by a variety of different age groups. However, the most surprising performance was when the entire village suddenly stormed into the open space on the field to dance in unison to Michael Jackson’s “Thriller.” Priceless!

Life here is not perfect, of course, but it is, for the most part, simple. It is in this simplicity that there is beauty, and, for a visitor like myself, my time here is not only serving for professional reasons but also as a reminder of what really matters in life. It is a reminder that we are not Americans, New Zealanders, Tongans or Niueans. We are all people, and we each have a human experience to live.

Alofi women play and sing traditional songs at the Alofi South Show Day (Photo by Hillary Sletten)

Alofi villagers groove some moves as they dance to Michael Jackson's "Thriller" at the Alofi South Show Day. (Photo by Hillary Sletten)

Sleuthing Like Nancy Drew – July 18, 2011

Hillary Sletten

Hillary Sletten in Avaiki Cave, Niue.  (Photo by Joe Lambert.)

Hillary Sletten in Avaiki Cave, Niue. (Photo by Joe Lambert.)

Palaha Cave is an example of a flank-margin cave on the west coast of Niue.  (Photo by Joe Lambert)

Palaha Cave is an example of a flank-margin cave on the west coast of Niue. (Photo by Joe Lambert)

I have come to realize that the Niuean caves are the wild frontier of the island. They are beautiful, mysterious and dangerous, and they are what make Niue geologically unique among the South Pacific islands.

Niue is a former atoll, or coral island, that once enclosed a lagoon, which was submerged up until about 5 million years ago. It was then uplifted to its current height of 20-60 meters above sea level. The exact cause of the uplift is uncertain and subject to debate, but it was likely caused by a combination of the island residing over a now dormant volcanic hot spot, as well as mid-ocean basin plate motion. Because Niue was once a reef and lagoonal system, it is composed mostly of carbonate rock. After millions of years of rainfall, dissolution of the carbonate rock has created a karst environment that is riddled with both ancient and modern cave systems.

The caves are where the majority of our field research takes place. The trick has been to figure out which cave will be the best one for our study of past climate. We are looking for a cave with stagnant air and lots of active stalagmites. A prize stalagmite will hopefully allow us to link the isotopic composition of the rainfall we collect at the meteorological station with the isotopic composition of the carbonate stalagmite and the dripwater from which it forms. This connection is what will allow us to derive a rainfall record extending up to 10,000 years ago and will help better determine El Niño/La Niña patterns during that time period. This may also help distinguish natural variability of climate change from manmade causes.

A member of the family who owns Ulupaka Cave guided us through the cave along with a staff member of the meteorological station in Alofi.  (Photo by Hillary Sletten)

A member of the family who owns Ulupaka Cave guided us through the cave along with a staff member of the meteorological station in Alofi. (Photo by Hillary Sletten)

We have spent the last week talking with several people to find out about the caves and get permission to visit them. We are learning that there is a lot of uncertainty about where many of them are located, particularly in the bush, and that only local family members know where the entrances are. This is surprising to me considering that many people live their whole lives on Niue, and it only takes 3 hours to drive around the entire island, but life is life.

The bush simply becomes a part of the backyard for many people. Since much of the history about the caves is scattered, our conversations have occurred at places such as the meteorological station, at the dinner table of locals, where we dined on fresh sushi and watermelon, in the middle of the bush, at the ice cream shop, where you can buy an albacore tuna and rent Indiana Jones all at once, and at the local dive shop run by a family from Australia. I feel like Nancy Drew on a mystery adventure with Paul and Joe, who are posing as the Hardy Boys. It’s quite the detectives’ chase.

Hillary Sletten sampling dripwater at Avaiki Cave, Niue for chemical analysis. (Photo by Joe Lambert)

Hillary Sletten sampling dripwater at Avaiki Cave, Niue for chemical analysis. (Photo by Joe Lambert)

Despite our sleuthing for a cave for our climate study, we have also explored a few caves that are easy to understand and access. These are the flank-margin caves that occur on the western coast. They were once formed inland and are now being cut into by shoreline wave action. The caves help mark the history of the island and of changing sea level, such that the caves at the highest points on the coast are the oldest when sea level was higher and the island lower. The lowest visible caves are the youngest, as they are being cut away by the ocean today. Most of these caves, such as Avaiki and Palaha, are open to the general public. Since arriving on Niue, Joe and I have collected dripwater from Avaki to compare its chemistry to that of samples collected by Paul and his former student, Michael Rasbury, in 2002.

The more challenging caves to find are the ones closer to the center of the island that have been formed by freshwater dissolution at the water table. These caves are not open to the sea and often have the characteristics we are looking for. Last Thursday we were granted permission to visit Ulupaka Cave on the eastside of the island, and, to our wonderful relief, we found stable air conditions and several stalagmites that will work nicely for our study. The cave itself is rugged and nearly every centimeter is covered in speleothems (including stalagmites and stalactites). I’ve never seen anything quite like it. One of the interesting features of this cave is the black soil deposit coating nearly the entire cave. We have yet to discover or talk to anyone who knows why Ulupaka has developed this way. My Nancy Drew investigations will have to continue.

Preparing for Research, Seeking a Cave – July 12, 2011

Hillary Sletten

Kololi Guesthouse

Kololi Guesthouse (photo by Joe Lambert)

I am sitting on the front porch at the main building at our guesthouse called Kololi. I am gazing out at a row of palm trees and they are gleaming in the early morning sun in front of a backdrop of brilliant blue sky and white clouds. The temperature is perfect as I sit here reading a book called “The Oceans and Climate” by Grant R. Bigg. I am reading about the Coriolis effect, which is produced by the motion of the solid earth and the revolving atmosphere moving at slightly different rates. I set my book down for a moment to ponder this phenomenon and, just as I do so, a strong breeze ruffles through the row of palms.

The Coriolis effect is what sets our near-surface winds in a westerly direction, resulting in the powerful Trade winds that legends of early explorers are made of. This simple yet expansive interaction of earth and atmosphere driving the momentum of air masses is also what brings us rain. For the island of Niue, like many other places around the world, rain is a life blood to survival. Niue has a unique hydrogeology that allows a large fresh groundwater lens to sit above the ocean water several meters below the center of the island’s ground surface, which was once an ancient lagoon. The only way this lens is recharged is though rainfall.

Since it is austral winter here, we are in the dry season. However, the first night we stayed on the island, I awoke to the roaring sound of rain at 4 a.m. I wish we had had our rain gauge set up at that time to start collecting the rainwater. This is an important part of our project. We will be collecting rain from Niue for the next year and analyzing the chemistry of the water, particularly the oxygen and hydrogen isotopes. We will be using this modern data to calibrate our data from the past to construct a climate record that we hope will extend up to 10,000 years.

Hillary Sletten installing the rain gauge with the assistance of Rossy Pulehetoa, Niue Climate Change Project Coordinator, and Shawn, a station staff member.

Hillary Sletten installing the rain gauge with the assistance of Rossy Pulehetoa, Niue Climate Change Project Coordinator, and Shawn, a station staff member. (photo by Joe Lambert)

As lovely as it would be, my team and I will not be able to lounge around paradise to simply collect rainwater, so we have collaborated with the staff at the Niue Meteorological Service to assist us with this task. On Monday morning we met with the director of meteorology and climate change, Sionetasi (Tasi) Pulehetoa, and his staff to explain and demonstrate our research objectives. It was quite exciting to meet Tasi and start making these connections. With the shake of a hand, it seemed our work instantly became official. Tasi and his staff are a wonderful and helpful group of people. To our delight, at the end of our meeting, we simply screwed our rain gauge onto a post at the station and we were open for business. Step one of our project was initiated.

Step two – finding a good cave to conduct our sample collection – is taking a bit more time and finesse. We think that one of the more private caves will be more promising for our study than one of the open-air sea caves that are visited by the public. We are waiting to see if we can gain access to these private caves. In the meantime, we brainstorm, visit the ocean, test our equipment, and make connections with the locals. We do a lot of thinking.

Dr. Paul Ahron presents an Alabama Stable Isotope Laboratory shirt to Sionetasi (Tasi) Pulehetoa, Director of Meteorology and Climate Change at the Niue Meteorological Service station.

Dr. Paul Ahron presents an Alabama Stable Isotope Laboratory shirt to Sionetasi (Tasi) Pulehetoa, Director of Meteorology and Climate Change at the Niue Meteorological Service station. (photo by Joe Lambert)

Hillary Sletten installing the rain gauge at the Niue Meteorological Service station next to the Hanan Aiport in Alofi.

Hillary Sletten installing the rain gauge at the Niue Meteorological Service station next to the Hanan Aiport in Alofi. (photo by Joe Lambert)

Getting There – July 9, 2011

Hillary Sletten

Welcome to Niue

Arrival at the Niue Airport in Alofi (capitol of Niue). (photo by Joe Lambert)

I am flying at 534 miles per hour at an altitude of 40,000 feet, the temperature outside is minus 67 degrees, and all I can see through my tiny window is a black abyss.  For a moment I catch myself thinking of that dark space and how foreign it is to be in it.  I am reshaping the definition of “lonely planet” in my head.  I have flown many times before, but never have I flown across the equator, the International Dateline, and the South Pacific.  Never before have I been in transit to an island in the middle of the ocean that probably 99.9 percent of Americans have never even heard of – one called Niue.  I’m curious to discover if this sense of loneliness will fade amidst Niue’s palms, sea caves and ocean views, or if it will linger far into my month-long adventure.

Dr. Paul Aharon, who is leading our expedition, is sitting on my left sleeping amidst the 300 or more passengers on the plane.  Dr. Joe Lambert, fellow geologist and field work organizer, is in front of me watching a DVD on his computer.  The plane is surprisingly quiet and I have just woken from several hours of rest.  I switch on the cartoon plane on my personal screen and watch it track our course across the Pacific Ocean.  I’m amazed at how slowly we are creeping across the ocean of this seemingly boundless world.  This is the 13-hour leg of our 56-hour journey to Niue.

I have read many things about Niue.  It became a country in 1974 and is the smallest democracy in the world.  It is in free association with New Zealand, making the New Zealand dollar the legal currency.  The island is 259 square kilometers and has a population of about 1,600 people.  I know that the island is struggling to survive and keep its young residents from moving to New Zealand and elsewhere.  What I have not read is whether or not I will be able to shed parts of my American self and become a part of Niuean life for a while.  I am excited for the challenge.

Baggage Claim

Hillary standing on left at the luggage carousel in the Auckland International Airport. (photo by Joe Lambert)

Before I know it, the flight crew is delivering a hot breakfast.  It is now 6 a.m. local time in Auckland.  My stomach has no idea what time zone it is in, but it knows good food when it gets it – eggs over an English muffin, roasted mushrooms, spinach, tomato, sausage and fruit.  We arrive in New Zealand at about 8 a.m. to find it rainy with winds up to 60 kilometers per hour.  Winter.  After making our way through over lit, intensely organized Duty Free stores and the customs desks, our group heads to baggage claim.  I watch the other blurry-eyed passengers as much as I watch the bags swirl around the conveyor. Every so often my attention is pulled away by a customs officer who is weaving in and out of people’s luggage with a small bloodhound.  Finally, I hear a sigh from Joe.  He has spotted the first of our three field containers.  He has spent two months preparing the field equipment for this trip and figuring out how to transport data loggers, pH solutions, drill bits and many odd things to a foreign island more than 6,519 miles away from home. I see the relief melt from his shoulders as he puts the last crate on the luggage cart.  We each grab our suitcases and we are on our way.

We all know what winter is like, but we are each shocked by the stark drop in temperature outside compared to the balmy heat of the Southeast and our climate controlled cabins.  I think we are all secretly happy we are only in Auckland for 24 hours before our flight to “The Rock”.

On our flight to Niue, I giggle out loud as I watch an Air New Zealand safety briefing hosted by Richard Simmons in which the flight crew is bouncing around in hot pink and turquoise spandex and leg warmers showing us how to use our air masks.  Apparently American culture has mixed itself into some of the strangest markets.  A score of Chris Brown, Fleet Foxes and Emmylou Harris sails me along.  My foot is tapping away.

My sunglasses are stowed in my checked bag, but I do my best to ignore the bright burst of light as I step off the plane onto the runway.  Waves of enchanting native music float to me from the band playing nearby to welcome us at the airport.  I catch myself grinning freely and start walking into a beautiful unknown.