1500 feet above the ground surface is where our suite of instruments normally operates, but for this flight we are taking them up higher, much higher, in fact over 20 times our normal range to 33,000 feet. Our flight plan is to repeat lines surveyed in a previous years by NASA’s Land, Vegetation Ice Sensor (LVIS) a scanning laser altimeter. LVIS has collected data as part of the IceBridge instrument suite in the past, but it was flown separately at high altitude on its own plane, in order to map large areas of both land and sea ice. This flight will refly some of LVIS’s work but using a subset of the instruments on our plane, narrow swath-scanning lidar, the digital mapping camera system, the gravimeter, and our depth radar.
At our higher elevation we will fly faster and can cover a lot of ground. The landscape of Antarctica can be hard to get ones head around – a glacier catchment is usually too big to fit into one field of view, so we see it bit by bit, and try to build up a physical picture in the same way we build up our understanding of the system – piece by piece. We have flown several missions into the Amundsen Sea region on the west Antarctic coast in the past, but this was the first time where we could really see the context of all of these different glaciers – flowing into the same embayment, forming ice shelves, calving ice bergs, and drifting northwards through the sea ice.
The flight offers views of some of the most noteworthy features in Antarctica. Pine Island Glacier, one of world’s fastest streaming glaciers, developed an 18 mile crack along its face in the fall of 2011 which spread further over the last few months. The crack will inevitably lead to breakage, dropping an iceberg which scientists have estimated will be close to 300 pound in size.
Bordering the glacier is one of two shield volcanoes we passed over during our flight. Pushing up through the Antarctic white mask, Mount Murphy diverts the ice streaming along the glacier. A steeply sloped massive 8 million year old peak, Mount Murphy pulls my thoughts back New York as it was named for an Antarctic bird expert from the American Museum of Natural History.
From Mount Murphy we continue to the second shield volcano, Mount Takahe. Ash from 7900 years ago found in an ice core from the neighboring Siple Dome has been attributed to an eruption from this volcano. This massive potentially active volcano is about 780 cubic kms in size. The volcano was named by a science team participating in the International Geophysical Year (1957-8) after the nickname of the plane providing their air support …an unusual name for a plane as its origin is that of a plump indigenous Māori bird from New Zealand which happens to be flightless! Regardless the rather round Mount Takahe soars high above the glacier as we move overtop.
From there we fly over the tongue of Thwaites Glacier as it calves icebergs into the Amundsen Sea. To read more about Thwaites check out my first blog of the season: http://blogs.ei.columbia.edu/2012/10/18/launching-the-season-with-a-key-mission-icebridge-antarctica-2012/
For more on the IceBridge project visit:
Named after Edith Ronne, the first American woman to set foot on this southern continent, the Ronne Ice Shelf is tucked just to the East of the Antarctic Peninsula on the backside of the Transantarctic Mountains. With an area measured at 422,000 square kms, this is the second largest ice shelf in Antarctica. This vast icy expanse stretches into an indentation in the Antarctic coastline called the Weddell Sea, and gained some attention this past spring when scientists identified a mechanism that will force warming ocean water up against Ronne, which over time will cause it to thin and weaken (Hellmer, H. H. et al., 2012). Ice shelves are important barriers slowing the flux of ice moving off the land into the surrounding ocean. Any weakening in the tight connection of this ice to the land, either at the bottom where the shelf freezes to the ground below or where at the edges where it is tightly fused to the continent, can have major impacts on the speed and volume (flux) of ice moving off the land and into the oceans.
The current mission is being flown to measure the flux of ice currently coming into the Ronne Ice Shelf from the surrounding Antarctic landmass. To determine this we focus on the ‘grounding line’, the area where the ice changes from being frozen solid to the land below to floating as part of the ice shelf. To understand how much ice is moving over the grounding line, we have to understand how much ice is at the grounding line, and to do this we have to fly along the grounding line (or slightly inshore of it).
In many areas of Antarctica, even knowing where the grounding line is takes a lot of work. Much of that work is done using satellite data through a process called “interferometry”. This process compares the returning radar signal from different satellite passes to determine where the ice begins to move under the influence of the ocean tides. In this scale, ice that is responding to the rise and fall of the tides is floating ice, and from this we can mark the grounding line. While technique identifies the grounding line, it does not show how much ice is moving across it; to determine that we need to collect ice thickness measurements. For today’s flight we moved just inland of the grounding line for about half of the Ronne Ice Shelf collecting ice thickness and other supporting data that will begin to fill in this important information.
Reference: Hellmer, H. H. et al. Nature, 2012. DOI:10.1038/nature11064.
For more on the IceBridge project visit:
By Ana Camila Gonzalez
“But can’t you see the rings already?” I ask, wondering why I’ve been asked to sand a sample- it sounds to me like one would damage a sample by subjecting it to the mechanical screech of a sander.
“Yes, but under the microscope they look foggy if you don’t sand them. Also, you’re looking at a black oak sample. You wouldn’t see any rings before sanding if you were looking at a Maple, for example.” Jackie responds. She shows me a maple core sample that she explains has been hand-sanded down to a 1200 grit. It’s smooth and shiny as can be; yet I can barely see what seem to be hairlines.
“Oh. That makes sense.” I secretly hope I won’t have look at another maple sample for a while.
I approach the machine. I look like a character from BioShock or a WWII soldier in the trenches, as I am wearing a respiration mask, goggles and ear muffs. Seemed a little excessive to me at first- once I turned the machine on and I saw the mushroom cloud of sawdust come off the banshee-screeching sander, however, I realized I’d be better off looking like a biohazard worker than having to bring an inhaler and hearing aid to work.
I place my first sample down on the sander, but it flies off and hits the wall… I guess I can hold it tighter and push it down a little harder. I try again but this time my sample stops the belt from spinning. Definitely too hard. Eventually I get just the right amount of pressure, and I realize I can tell because my sample looks clearer every time I take it off the belt. I start humming to myself, singing something along the lines of I can see clearly now, the rings are there… As I go to higher and higher grits and my sample starts developing a cloudless luster, I realize I enjoy this a little too much.
To me, sanding is a process full of Zen. It’s a process I can focus on while still letting my mind wander, and my thoughts usually get pretty philosophical- I have this foggy, unclear sample and slowly I take off its layers and layers of disparities. What results is a core in its purest form ready to tell the story of its life, and after a few hours of sanding I’m ready to listen.
Ana Camila Gonzalez is a first-year environmental science and creative writing student at Columbia University at the Tree Ring Laboratory of Lamont-Doherty Earth Observatory. She will be blogging on the process of tree-ring analysis, from field work to scientific presentations.
One piece of our IceBridge mission focuses on sea ice here in the south. Sea ice in the northern regions has been reducing at dramatic rates over the last decade, setting a new record just this year, but the story in the south is not so clear. In fact, there has been a buzz that Antarctic sea ice extent may just be increasing while the Arctic ice is decreasing. The issue is a complex one and involves not just sea ice extent (how much surface area the ice covers) but sea ice thickness (total volume of ice). While the extent of Antarctic sea ice is increasing, we also need to understand how the thickness is varying.
One of the trickier items in measuring sea ice is making the raw measurements of thicker and thinner ice. With only satellite measurements it is hard to get the true thickness of the ice, since the surface of the ice is often covered with snow that needs to be accounted for in our calculations. Using the snow radar on the IceBridge mission we can work out how much of what the satellite is measuring is actually snow.
The Bellinghausen Sea sits just to the west of the Antarctic peninsula and in the southern winter months is generally covered with sea ice. We have flown two Bellinghausen sea missions this season – one to map out to the furthest edges and another to looks at the gradient of sea ice change as you move away from the coast or shoreline. The second Bellinghausen mission was important because in running profiles in and out from the coast it allowed us to measure how ice thickness patterns vary with distance from the shore. We need to understand these patterns of ice thickness in the southern end of the planet, how they may be changing and what connection they have to the climate system.
There has been much less study done on southern sea ice than northern sea ice because we get very few opportunities to make the measurements we need. We have two high priority flights to the Weddell Sea (on the eastern side of the Antarctic peninsula), but so far it has not been possible to fly them because of the weather. Hopefully before the end of this season we will be able to fly both these flights and fill in more pieces in the sea ice story.
For more on the IceBridge project visit:
Last year IceBridge had its first flights into East Antarctica when it flew some missions into the Recovery Glacier area. Recovery is a section of Antarctic ice that lies east of the peninsular arm of West Antarctica, tucked behind the Transantarctic Mountains, a dividing line that separates west from east. We know from Satellite data that Recovery and its tributaries have a deep reach, stretching well inland to capture ice and move it out into the Filchner Ice Shelf draining a large section of the East Antarctic ice sheet. But there is a lot we don’t know about Recovery because the remoteness of the area has limited the number of surveys.
Several recent works have showed us that this area is important. Satellite measurements of the ice surface show small patches along the trunk of the glacier that are changing elevation more than their surroundings. These patches have been interpreted as lakes that lie under the ice sheet, coined the Recovery Subglacial Lakes. The lakes appear to drain and refill over time as the surface elevation over the lakes changes. To learn more about them and what they might tell us about the behavior of the glacier, we need to look under the ice.
But there is more we need to understand about this remote area, including simply needing to know the size and shape of the channel that delivers this ice out to the ice shelf and towards the Weddell Sea. Last year’s mission gave us some data points to outline the channel, but this year will help us provide a more complete imaging of what lies below this East Antarctic ice conveyor belt.
We will fly cross sections along the lines of the retired ICESat satellite tracks, allowing us to compare the laser measurements we make of ice surface elevation to those made during the satellite mission. We will end the day flying along the Recovery channel to get another look at one of the interpreted lakes. Combining last years’ data, ICESat data and this year’s data will give us a better picture of the area that has been carved beneath the Recovery glacier, the amount of ice that can be moved through the glacier and its tributaries, and how the lakes under the ice might fit into the larger story.
After waking up in the Rupsa River in Khulna, we watched as the Vanderbilt University group studying sedimentation around Polder 32 arrived on Bachchu’s boat. They pulled up alongside and we spent some time catching up with each other’s trips before it was time to hit the road. Our last site is nearly at the northernmost tip of Bangladesh. This one is for tectonics. The 2-km high uplift block of Shillong, is roughly coincident with the Indian state of Meghalaya (Abode of the Cloud). It was the site of a M8.1 earthquake in 1897, although the exact fault that ruptured is uncertain. Our existing GPS indicate that it is moving south at ~7mm/y, but there is a suggestion that it is rotating clockwise, meaning the western end would be moving slower. Our GPS is going in Bangladesh just to the west of Shillong. However, the Brahmaputra River has eroded away the western margin and buried the remnants under sediments. We have to be far enough north to be on the Shillong-Assam block and away from the several faults on its southern side. We settled on the town of Bharungamari. It is literally the end of the road, only a few miles from the Indian border.
So we set off on a 400 km drive. Along the way, we stopped at Kushtia and visited Humayun’s childhood home and met his sister-in-law and nephew. Then lunch and across the Ganges River. At our first flat tire, we has tea in a small shop – Humayun had them pour boiling water on the glasses for us. At the second it was green cocoanuts. The driver switched to the spare tire while Sarah attracted a large crowd of locals. When we finally got to the hotel it was almost 10pm, about 12 1/2 hours after we left the Kokilmoni. At least it is one of the nicer hotels that I have stayed at in Bangladesh.
The next morning was a more leisurely 8am departure. For breakfast, we were joined by Atiqulla, one of Humayun’s fourth year students who is from Bhurungamari. He scouted the site and would lead us there, the local hospital. We squeezed the extra person into the van and headed north. We got there late morning, scouted out the roof and located a site for the antenna and for the receiver. Getting there meant walking through a hallway with beds containing patients at the hospital. It seems we have had two modes during this trip, either start very early and then have breakfast at noon, or have breakfast first and then have lunch after 4pm. This was the latter. You could tell we were getting worn out. We were having more trouble keeping track of some of the small screws and tools we needed. We started running out of anchors for attaching cables to the wall. Still, we got it done, although it is not our prettiest site.. However, Humayun did a great job with the grounding rod, having a channel cut in the concrete apron around the building, running the wire through a conduit and then recementing over it.
By the time we were done, it was 3:30 and the hospital administrator and some of the staff came to see the site. By the time Humayun finished explaining th purpose of the GPS, we were more than ready to get some lunch. What I didn’t know was that we were invited to Atiqulla house for lunch. We went to the house of his extended family, parents, siblings and nieces and nephews where we were served a feast. The five of us ate while the family and a large group of neighbors looked on and chatted with us. We had chicken, squab and beef along with boiled and pilao rice, paratha (bread), vegetables, dal (lentils), and cucumbers. A veritable feast and a good ending for the last GPS installation.
We stuffed our selves and headed back to Dhaka, staying overnight at Bogra, 4 hours away. Along the way we passed celebrations of Durga Puja, the largest Hindu festival in Bangladesh, and lots of cattle and other animals being transported for Eid ul-Azha, the feast of the sacrifice, to be celebrated this weekend. After arriving in Bogra, we celebrated with a beer at the first bar I’ve ever seen in Bangladesh.
We sailed out of the small channel we were anchored in to the Sibsa River and then to the south. We passed the western side of Polder 32 with a good view of the embankment that protects the island then passed into the Sundarbans forest with mangrove trees on either side of the wide river. Hiron Point is close to the mouth of the river where it empties into the Bay of Bengal. Perhaps empties is not quite the right word as the river is tidal, flowing both ways. Moreover, the mud that maintains the Sundarbans probably comes from the sea. The sediment discharged by the combined Ganges-Brahmaputra-Meghna Rivers is swept westward along the coast and some of it is carried inland by tides and storms. How much is still a topic of research. We prepared the equipment in the bow while watching for tigers along the shore. We reached our anchorage after about 8 hours and enjoyed a BBQ on the top deck. Then, at last, an early night.
Just after 6AM we loaded the launch and headed into the channel with the forest station after watching the sunrise. We were accompanied by two armed guards, required in the Sundarbans, although we don’t expect tigers at the ranger station. The first thing we passed was the tide gauge, the reason we are putting the GPS as this particular location. It is well known and its data is available in a global repository for tide gauge data. We landed at the third dock belonging to the forest service. The path to the ranger station proudly announced the Sundarban as a World Heritage Site and through in a couple of caged tiger statues as well. We met the forest ranger and were told that there is no cell phone service, contradicting what we had been told. During the winter there is a weak signal. That was going to be a problem for downloading the data. We headed to the roof and for once, the ladder was already in place.
The roof had a low brick wall around its perimeter. Brick is much weaker than reinforced concrete and not considered stable enough for GPS. Our two foot threaded rod was long enough to get us 5” into the concrete is we drove the long drill bit all the way to the chuck. It would have to do. The GPS went into a secure room with communications equipment. By now our experienced team split into our familiar tasks. Sarah figured out a way to get the cables to the roof by tying them to a rope after going through the wall. After some effort, I managed to drill the wall to the maximum depth. With the poor to nonexistent cell signal, we set up a yagi directional antenna and pointed towards the closest cell phone tower some 60 km away.
We got everything set up, but the cellular connection didn’t work. Next step is to hope that we can establish a connection in the winter and be able to seasonally download the data. Having to return regularly to download the data or come back to set up a radio link would be expensive, although the Sundarbans is a wonderful place. We said our goodbyes and headed back to the M/V Kokilmoni without having seen either a tiger or a crocodile, although we saw a lot of mudskippers, a personal favorite of mine while leaving.
We weighed anchor and headed back north to Khulna. The crew spotted a crocodile, but I missed it while uploading blogs. Going north, we had left the calm of the Sundarbans and returned to the modern electronic world of cell phones and internet. One more GPS to go, but it is in far northern Bangladesh, a 380 km drive from Khulna where we get off the boat tomorrow.
When we finally got to Khulna, the second largest city in Bangladesh, Bachchu, who organized the boat, met us and led us down country roads to where we met our boat, the M/V Kokilmoni, our home for the next few days. It is very large for the four of us and Bacchu, but faster and safer when there is still a risk of cyclones, as hurricanes are called in the Indian Ocean. Luckily the forecast is for 10 days of clear sky and 90° weather. When we got to the dock (ghat in Bangla), a crew from the ship was there with the launch to ferry us and our loads of equipment to the ship. After stowing it all away, dinner at a reasonable time.
The Kokilmoni sailed down the channel to near the location we will install our GPS on Polder 32. Back in the 1960s, Bangladesh (then East Pakistan) constructed embankments or polders around much of the low-lying coastal region. The region is crisscrossed by numerous interconnecting rivers separating the land into islands. The government built embankments around many of them to protect them from flooding. However, they also prevented the sedimentation necessary to maintain the land. Without either flooding or sediment, the sediments compacted and the land subsided so that it is now 3-4 feet below the land outside the polders that continue to get sedimentation. This set the stage for Cyclone Aila in 2009 and the storm breached the embankment in multiple places. Initial repairs did not hold and the island was submerged for most of two years. What should be done for the poldered areas in the face of continued sea level rise is a major question. Our GPS will provide much needed data on the rate of subsidence.
Polder 32 is a main focus site of a large project funded by ONR, the Office of Naval Research. This project looks at not just the physical side of the balance of sea level rise, subsidence and sedimentation, but also the local population’s interaction with the environment and their potential response to disasters, such as temporary or permanent migration. In fact, social scientists make up the most of the project. The lead institution of this project is Vanderbilt University and there is a group of them here at Polder 32, too. Unfortunately they are on the opposite side of the island, so we were unable to meet up. Neither of us had the few hours to spare to sail over to the other.
Anyway, we again prepared the GPS equipment into the night, then work up early to install the GPS. At least on the Kokilmoni, there was tea and cookies to help us cope with the 6AM start. Plus we had a crew to help carry everything to the site, including a very heavy diesel generator to provide power for the drill. They dropped us off at a dock connected by a bamboo bridge to shore, then moved to a place where they could offload the equipment. They insisted on carrying everything for the 1-kilometer walk to the elementary school we will use.
In May, Dhiman and Steve did an elevation survey of the entire polder and set up a reference station at the school. Then they left the GPS there to get a head start on collecting data with a temporary “campaign” set up. When we got to the roof, we saw the installed antenna, but the GPS had failed. The flimsy portable solar panel could not hold up to the monsoon. Still the data for May and June it go will be valuable and the antenna is already installed. After a discussion with the headmaster about where to put the receiver, we put it in their computer room (solar powered). Just outside is a statue of the Hindu goddess of education as this village is almost entirely Hindu.
We went to work, with our now experienced team splitting up the tasks, with Sarah doing the most technical parts. I drilled the holes in the roof and bolted the solar panel down and secured the antenna cable to the roof. When it was done, we headed back to the ship to head to Hiron Point in the Sundarbans, the world’s largest mangrove forest and nature preserve that is home to 350-400 tigers. And we finally got to eat a lunch at a reasonable time. As a Sundarban tourist boat, the Kokilmoni has very good food.
We spent the entire day traveling to get to Khepupara, not far from the Bay of Bengal. We had heard that there were problems at Mawa Ghat, the ferry crossing of the Padma River immediately south of Dhaka due to siltation on one side and erosion on the other. We decided to head west to Aricha, the shorter ferry ride near the confluence where the Ganges and Brahmaputra meet to become the Padma. Unfortunately, the traffic to get out of Dhaka on the western side was so bad, that it and the longer route lost us more time than using Mawa. We didn’t arrive at Khepupara until after dark even though we started before 6AM. At least after the ferry, we had beautiful scenery of rice fields and forests. I am always glad to get away from Dhaka traffic.
Khepupara is a site where a long tide gauge record shows a very rapid rise of water level implying sinking of the land. However, tide gauges are not designed to be stable over decades, so I don’t trust the rate. We are putting a GPS here to get our own subsidence rate in a few years time. Humayun arranged for it to be installed at the Bangladesh Meteorology Department (BMD) weather radar station. We stayed in their guesthouse, pretty basic accommodations, but it suited us just fine. We walked to a local restaurant for some delicious Bangladeshi food then started preparing the equipment to save time. That took us up to about 11:30 PM with a few short power outages. Then we crashed.
The next morning we started at 6AM to install before breakfast. We went to meet the officials and check out the suitability of the roof of their headquarters building, once a ladder was found. It was reinforced concrete, but the two good corners of the highest roof had a weather vane and anemometer installed. The two back ones had their sky view blocked by a water tank. We went back to the guesthouse and decided that its roof was the better option and had to carry everything back. By the time we finished installing the antenna, the solar panels to power it, grounding rods and lightning protectors, etc. and Sarah checked that everything was working, it was 11AM. Breakfast became brunch for our famished group.
This site took longer, in part, because it will have cellular communications. The three coastal sites we are doing are very remote, particularly the other two that can only be reached by boat. We decided to use cellular modems. Every day UNAVCO in Boulder, CO will be able to call up the GPS and download the day’s data. It will only have to be visited if it stops working. Using solar panels with 2 car batteries to store power, the system is very self contained.
Two down. Next, we drive northwest to get on a boat to take us to Polder 32. An inland island whose embankments to protect the area from flooding failed during Cyclone Aila leaving it underwater for most of two years. Our late finish meant abandoning two secondary items on our agenda. Visiting our compaction meter site to download the GPS data and installing a replacement GPS at Khulna University to replace the one that is no longer working. Humayun will come down here in November to do it himself. While they are close to on our way, we don’t reach the boat until after dark. It is the M.V. Kokilmoni, the boat that I lived on for two weeks last year when we did a month-long seismic cruise on the rivers throughout Bangladesh.
October 2012 IceBridge Antarctica resumes … Mission goal…monitoring the polar regions…Mission target… determine changes in ice cover and thickness, refine models for future sea level rise…Mission instruments…airborne geophysics. Good luck team.
The crews have spent the last few weeks in Palmdale, where the DC8 is based, for instrument installation and test flights prior to our move down to Punta Arenas, our home base for IceBridge Antarctica.
Instrument Run Down: We are flying with the same instrument suite as last year allowing us to see above, below and through the ice. Laser altimetry, for surface ice measurements, measured by the NASA Airborne Topographic Mapper, visible band photography, to allow for draped imagery, from NASA’s DMS (Digital Mapping System), three radar systems from Cresis to measure the ice thickness, composition and bed imagery (MCoRDS, Snow and KU band) and gravity to refine what is under the ice with Lamont using Sander Geophysics’ AIRGrav gravimeter.
ATM and the gravimeter both require GPS base stations on the ground throughout the deployment. Combined with the GPS receivers on the plane these allow very precise positioning of the aircraft, and the sensors on board, which is critical to all the measurements we make. Setting up the GPS stations is one of the first jobs in Punta Arenas.
Our First Mission for 2012 is Thwaites Glacier – Going Straight to the Heart of the Changes. On our way out of Punta Arenas, out past the airport, I noticed this feature in the landscape:
It appears to be the paleo-shoreline from the last interglacial (~80,000 yr BP), when sea level was higher than present. The very flat terrain results in any sea level change causing a large shoreline retreat. Evidence like this of changing shorelines, is one method scientists use to determine past sea level under a different climate. As we study different areas around the world, we must account for the local changes in how the land has risen or fallen. Changes in sea level can be a combination of an adjusted world/ocean wide (eustatic) sea level and the more local response from the rebounding (isostatic ) of the land that was previously depressed under a glacier as local ice is unloaded during deglaciation. Here the history of the shoreline was governed by a combination of changes in eustatic sea level and the isostatic response to deglaciation of the local ice load (De Muro et al. 2012). Putting together information from around the world we eventually build up a picture of the global changes that have occurred in sea level. Changes in sea level are directly connected to our work monitoring polar ice.
When we fly over the ice, we are monitoring how the ice sheets are changing at present, and learning how to understand the complicated interactions between the atmosphere, the ocean and the ice. Studying this helps us to understand which ice bodies are most likely to contribute to sea level, how quickly they changed in the past, and how quickly they might change in the future. It’s good to get this reminder as we head out on our first flight – especially as it is to survey the area where the glacier switches from being frozen to the land below [the bed] to where it goes afloat, called the ‘grounding line’.
Our first flight of the season will be along the Thwaites Glacier. Thwaites and Pine Island Glacier are two ‘glaciers of interest’, both large outlet glaciers that serve as conduits out of the ice mass of the West Antarctic Ice Sheet (WAIS), moving ice off the land into the surrounding ocean, and long considered its Achilles heel. Thwaites glacier has a very wide region of fast ice flow over its grounding line, and a relatively small change in that width has the potential to greatly increase the flux of ice into the ocean. Through the radar and gravity measurements collected on previous IceBridge missions we have been able to get a sense of the bed shape tipping downward as you move inland from the ice edge, and where pockets of water lie under the icesheet. Our goal today is to collect enough data to develop a more complete image of what lies under the ice in this area.
2009 Operation IceBridge surveyed a grid in front of Thwaites grounding line and identified a ridge in the rock of the sea floor. In the last few months a large section of Thwaites glacial tongue broke off just seaward of that ridge. This mission will fly back and forth along nine lines parallel to the grounding line of Thwaites glacier. In combination with flights from previous years, this will give us a map of the grounding zone at 2.5 km spacing.
We are hoping to learn more about goes on underneath this icy reach of the Earth each time we take flight.
I’m back in Bangladesh for the fourth time in the last two years, my eighth trip overall. It is the first time I’ve been here in October. It is about 90° and sunny. The monsoon is over, but water levels are still high. I have come to install more GPS around the country. With me is Sarah Doelger, an engineer from UNAVCO, an organization that provides technical support for research involving GPS. A number of out GPS stations in Bangladesh are systems on loan from UNAVCO. She has come along because we are establishing stations in remote areas and will use the cell phone system to call the receivers and download the data. I am also traveling around with Humayun Akhter, my partner for many years from Dhaka University, who keeps our network running, and his student Fayazul Kabir. The four of us will be traveling around the country by van and boat to install the stations to monitor tectonics and land subsidence.
As usual, we arrived at 4 AM after a full day or traveling and had to hit the ground running. After a short rest and shower at our hotel, we spent the day unpacking, preparing the equipment and buying the last few items.
Yesterday, was our first installation. We drove east to Comilla University sitting on the last exposed hill of the foldbelt. At a little over 100 ft high, it may not seem like much, but it stands out in a country where half the land is less than 10 ft above sea level. Thanks to bad traffic, it took 4 hours to get there, including a stop for breakfast on an island in the Meghna River. We met with the registrar over tea and cookies, then finally got to work about noon. This site fills a gap in our coverage of the Burma Arc foldbelt, a continuation of the same plate boundary as Sumatra, site of the 2004 M9.3 earthquake and tsunami. Here, the subduction zone is colliding with the largest delta in the world, folding the sediments into a broad set of folds.
Our GPS is measuring the rate of shortening of the foldbelt as strain builds up, possibly towards an earthquake. The antenna was attached to a 2-ft steel rod we cement into the roof of a reinforced-concrete University building. This is our preferred method for a country with almost no solid rock. The receiver, electronics and backup battery were installed in the control room of the large solar panel array just below the antenna. The only hiccup was tapping into their electric system for power and meshing their 2 wire system to our 3 wire system. Their system is not grounded, as we discovered when Sarah got shocked connecting our battery. He fingers have stopped tingling. It took a while to understand what we wanted and in the end we had to ground our system into the lightning protection grounding that we set up. It was all done in about 3 hours and stopped for a well-deserved lunch at about 4 PM on the way home, further hampered by traffic jams.
This morning we packed all our stuff in a large van and are working our way through the traffic to get to SW Bangladesh for the next 3 stations. I am really looking forward to getting out of the city and its traffic and into the calmer countryside.
By Ana Camila Gonzalez
My feet are soaking wet and I’m playing a game of Marco Polo, but I’m nowhere near a pool. It’s my second day on the job. It’s my second week of college. I have no idea what to expect.
I’m a first year undergraduate student at Columbia University, and I just began to work at the Tree Ring Lab at the Lamont-Doherty Earth Observatory after being told by a few upperclassmen that the Lamont campus “just isn’t for freshmen”.
On Friday, September 21st, several members of the lab headed to New Paltz, NY to do some field sampling for a project aiming to uncover particularly major ecological events in the Eastern United States in the past three hundred years. I had just started to understand the basic concepts of differing tree rings. When I was told we’d be coring trees and identifying them, I smiled and nodded my head enthusiastically. You should see my poker face.
We get to the town of New Paltz and drive right through the center, heading towards Minnewaska State Park.
After a deceivingly easy one mile hike on road-like paths, we get to the entrance point for the plot that was pre-designated Jackie, Dario, and Neil earlier in the spring. From that point on, I get to witness the transition from a suburban hike to what seems to be the set of Jurassic Park. We’re heading into the area surrounding a ravine, and my feet remind me that I’m not wearing waterproof boots. At some points I feel like I’m in a maze, and I start yelling MARCO! At that point I start remembering that I took the job because I wanted some hands-on experience in the field of environmental science. Grabbing the four-foot fern in front of me, I feel that I’ve made the right choice.
After some strolling, climbing and maneuvering, we finally reach the plot. Here I finally get to see what the overall project is really about.
While some forest ecosystems in the Western United States recycle nutrients and move through successional cycles at fairly large scales through natural and necessary fires, these processes are much slower and do not seem to occur at larger scales in the temperate forests of the Northeast. Trees experiencing suppressed growth only receive the necessary sunlight, water, and nutrients to experience quicker growth when surrounding competing trees perish, either through logging, disease, windstorms, or similar ecological processes. One can see this change as a drastic change in the width of tree rings: once a previously suppressed tree becomes dominant, the increased growth results in relatively wider tree rings.
When this drastic change is seen not only in the rings of one or two trees but across an entire forest ecosystem, a major ecological event is likely the cause. This project is aiming to find the causes of a few suspected major ecological events in the Eastern United States.
In New Paltz in particular, this project encountered a roadblock- some people believed our study forest in Minnewaska State Park was an old-growth forest, but so far the samples brought back have found evidence of logging in the late 1800s. The first samplings, using plots with a radius of 20 meters, returned few older trees that would be useful to the project. The radius was thus increased to 30 meters, and only trees with diameter greater than 40cm were cored past the 20 meter mark. After this adjustment, the second sampling returned double the amount of older trees. The real science can begin.
So here I am, learning all of this for the first time, and I’m fascinated. Another new student and I learn to core a tree, and we realize how physically strenuous it is, laughing about having to lift weights to get in shape for future fieldwork. Like that’s ever going to happen. We’re introduced to a few different tree species during the process, and we begin to learn how to identify them. For the past few days I’ve walked around trying to identify every tree in Morningside Park.
At the end of the day, I’m feeling pretty fulfilled. The way back to the trail isn’t as cinematic as my entrance through Jurassic Park, but I still feel like I won’t get up after sitting down in the car.
That night, I got a rare chance to talk to my cousin, a botanist in Cuba. I told him about my day and he told me that if I start beginning to enjoy science, and the general act of finding answers to questions others might not have thought of asking, it becomes an obsession. He told me I wouldn’t be able to get away from it. I think I’m starting to get a sense of that. I was hoping to land a job at the LDEO that would just let me begin to get my feet wet in environmental science. So far they’ve gotten soaked, but I have a feeling I’ve only started to dip my feet in the water.
This is the first in a series of guest posts by Ana Gonzalez, a first-year environmental science and creative writing student at Columbia University. Ana is a research assistant at the Tree Ring Laboratory of Lamont-Doherty Earth Observatory who will be blogging on the process of tree-ring analysis starting off with the joys of field work.
2012 is turning out to be an exceptional year in the eastern US. Starting out with what was essentially a #YearWithoutaWinter, followed by a heat wave in March, a hot summer, Macoun and Cortland apples coming in 2-3 weeks early, and the continuation of a severe drought in the Southern US that expanded into the Midwest and Northeast, this year’s climate doesn’t appear ‘normal’. From a 500-year perspective, this year’s drought in the northeast should actually feel like an exception for 58.2% of its people. While there have been droughts in the Northeast over the last 44 years, trees informed us that, as of 2011, we were living one of the wettest 43-year periods since 1531. It is shocking to see towns flood or covered bridges float away during tropical storms in the northeast. But, our new record suggests that the buildup of soil moisture prior to these storms might make these unusual[?] storms the norm.
Immediately preceding this epic pluvial (a period of increased precipitation) was the 1960s drought, one of the most intense droughts of the last 500 years. Having lived only during this epic pluvial, I cannot fathom this drought. Pluvial is my norm. So, every time I lead a hike or lab tour on campus, like during Lamont’s great Open House, I always ask if someone was alive during the 1960s drought. Heads tilt back, eyes come alive, and the stories pour out. People talk about tough times and odd events like a landfill catching on fire. I then congratulate them for surviving one of the worst droughts of the last 500 years. Then I have to say, “Uh, but it has been worse. Much worse.”
Often when looking deeper into Earth history, we see things that send shivers up our spine. For those who lived through the 1960s drought, our new record should send shivers up your spine. Our lab’s first study showed the 1960s drought to be the worst since 1700. However, when looking back almost another 200 years, we can say things like, “Yeah, the 1960s drought was bad, but it was only six years in duration.” [six years of below average conditions in our new record] Six years of drought is tough. It must have felt like a decade. But, how might we feel about 23 years of drought? How might a 23-year drought feel when the preceding 11 years had only a few years of average to above average precipitation? [shivers].
The current epic pluvial caps a 150-year wetting trend for the Northeastern US. This trend, however, is not limited to the Northeast. Much of the entire Eastern US has become wetter over the last 150 years. Only the Deep South has trended towards drought over the last 20-30 years.
For more on the development of our new record and some of the implications of what we found, go here. The rest of this post focuses on the contribution of biodiversity and broadleaf species to the new record.
Biodiversity, Broadleaf Species, & Tree-ring Reconstructions in Humid Regions
An interesting result of our study was that the use of a greater number of species can improve a tree-ring based reconstruction (for more examples, see here, here, here, here). Reconstructions have been made using multiple species in humid regions like southeastern NY State since the beginning, so the use of multiple species in not groundbreaking. But, our initial analysis indicates that using 10 records drawn from 10 species outperforms the 10 best chronologies regardless of species (best is defined as the strongest correlation to the climate data used for reconstruction). It seems biodiversity is not only good for life, it can be good for reconstructions of past climate.
We are not exactly sure why increased diversity might improve reconstructions. My pet hypothesis is that each species has a different sensitivity to its environment and that by combining multiple species, differing responses are filtered out, resulting in a more accurate common signal. Some of this is driven by genetics. Some of it could be driven by the ecology of the sites where trees live. Think of it in human terms: some people can eat whatever they want and never gain weight. Some of us look at a banana split and gain two pounds. We might disagree on what we want for dessert, but when offered a fine blueberry pie, or for us sweet tooths – maple cream pie, we can generally agree if it is righteous. I imagine trees have a similar response.
“Remember 1972? Wow, that was a good water year!”
“ Yes, that was a good year, but I really liked 1989.”
“Oh yeah, that was a good year. But what about 1833?”
All 27 records chime in chorus, “Most righteous. Water. Ever!!”
These findings bode well as tree-ring scientists move into new regions of study – say the rich, temperate, broadleaf forests of Asia, for example. Regions with a vast array of tree species could be a boon for the future of dendroclimatology (the reconstruction of climate from tree rings).
Thinking about how we can improve reconstructions is important. Many scientists are exploring new statistical techniques to extract a chorus of solidarity from trees. From a biological perspective, though, the rate of extinction (literal and functional) is a real threat to our science. Hemlock woolly-adelgid is wiping out hemlock trees, a stalwart species and one of the backbones of the North American Drought Atlas. The loss of hemlock and other important species will thus diminish future reconstructions. Replacements species are needed.
Of the 12 species used in our study, eight are broadleaf species. We found that tuliptree or tulip-poplar (Liriodendron tulipifera) is one of the best species to replace hemlock*. Not only is it drought-sensitive, it has shown to be long-lived: a 512 years old specimen was recently found. Amazingly, only about half of its radius was recovered, as the tree was hollow. I would guess this species can live 600 to 700 years, if not more.
Our study also found other broadleaf species suitable for dendroclimatic research. These species include: black birch (for Yanques, but sweet birch for Southerners; Betula lenta), pignut and shagbark hickory (Carya glabra and Cary ovata, respectively), and northern red oak (Quercus rubra). While these trees do not live as long as hemlock or tulip, they are proving to live longer than expected. Continued exploration of species in the diverse eastern North American forest for maximum ages and climatic sensitivity should help dendroclimatological research as species are lost.
* Tuliptree is quickly becoming one of my favorite trees. It great longevity is a real treat. It is now the tallest documented tree in eastern North America now, too. But, it is how it handles drought that is so fun. Tuliptree is a drought-deciduous species, meaning that, during drought, it cannot close its stomata as well as other species to staunch the loss of water from its leaves. Therefore, it drops leaves to reduce water loss. If you paid attention to this tree in 2012, you would have noticed yellow leaves in July, a more common leaf color in September.
The really, really cool thing about this species, however, is that it also has indeterminate growth. This means that, unlike many temperate trees, its growth is not limited or set prior to the growing season. I once saw tuliptrees putting on new leaves in September following a dry August. This plasticity is awesome. It also suggests that September Song is not necessarily mournful for tuliptrees.
What is the meaning of water? In my everyday life, water is a given. Even this year, when at least one quarter of the US has been stricken by drought, water continues to flow from the tap and my family is unaffected by its scarcity. I remember the California droughts of the 1970s, when my brother and I shared bathwater, I learned not to flush so much, and water was rationed. Even still, our very sustenance, our wealth was not threatened by the lack of water. In Mongolia, as in many other developing countries, people depend on water not just to slake their thirst but to sustain their livelihoods. Mongolian herders must bring their animals to a water body daily. In times of drought, most lakes dry up, leaving only a few “permanent” lakes available to dozens of herders and thousands (hundreds of thousands?) of animals. Steppe lakes also serve as virtual “gas stations” for migratory birds and waterfowl – they are hotspots of diversity. Without water, animals perish, food disappears, and people and ecosystems suffer. In a semi-arid region like the steppe, water allows people and ecosystems to transform solar energy into a mobile and flexible product via photosynthesis and primary consumption by livestock. In Mongolia, water is energy.
As part of our new project, we will be collaborating with Avery Cook-Shinneman (University of Washington) to use lake sediments to reconstruct the ecology of lakes and livestock during the Mongol Empire. Lake sediments can provide a broad array of proxies for past ecosystems. We plan to use some of these proxies to estimate past water quality and a relatively new proxy, Sporormiella, to assess the numbers of livestock present during the Mongol Empire. This summer, my student John Burkhart and I visited a number of lakes near the Orkhon Valley, seat of the Mongol Empire, to recon possible sample sites. In the process, we learned to appreciate the role of permanent lakes in Mongol herders’ livelihoods.
Before leaving for Mongolia, we had worked with Avery to identify more than a dozen lakes to recon. We were going to collect water and surface sediment samples from each lake to assess their potential. But upon our arrival in the Orkhon region, we quickly learned that those lakes no longer existed. The decade-long drought that might be only ending in 2012 had left only a few permanent lakes; we noticed much standing water along the highway compared to 2010. Though the large lakes we identified on Google Earth were starting to fill up again, the fact that they had dried up during a recent drought suggested they had dried up in the past, leaving only an intermittent record of past ecology. We began visiting local herders homes (“gers”) to inquire about permanent lakes.
We had used this approach before to look for old trees but Mongolians are no better than Americans at identifying old trees. They always point you to the biggest, most beautiful tree and claim it’s the oldest – when in fact the scraggliest, ugliest tree is usually much older (Editor’s note: Beauty is in the eye of the beholder). But in the case of lakes, these Mongolian herders were true scholars. Ask any old herder about where to find permanent lakes, and they will tell you in detail the characteristics of all lakes in their region – when they thaw, when they freeze, what kind of plants grow around it and in it, and how likely it is to dry up. I should not have been surprised – their life and livelihood depends on their knowledge and careful management of these lakes.
This kind of ecological knowledge is not new. Mongolians have cultivated knowledge of lakes for millennia. The first permanent lake we visited was less than 5km away from an Uyghur fortress dating to the 8th century.
We have just made it back to Ulaanbaatar after 11 days of in-country travel and field work. While being a bit field worn from working on a lava field for 6 days, we are simultaneously thrilled and in good spirits. It is a bit too early to say, but it seems that Summer 2012 in Mongolia was a success*. It certainly felt like a success to me on the day we came full circle from 2010.
Amy, John, and Sanaa were a day ahead of us and, with John being down with a case of Chinggis’ revenge, Amy and Sanaa spent a full day on the lava field revisiting and re-visioning how we would sample over the following week. The hopeful goal was to collect enough wood to push the chronology near 2000 years in length while having enough samples over the last 1000 years to be able to say something with statistical significance. Sanaa and Amy intensely studied where to find wood and what pieces might be from an earlier era. They accomplished this while collecting 24 cross-sections of deadwood. It was an impressive and hugely helpful first day.
It was necessary to study the characteristics of the deadwood and its geographic distribution across the lava field because, honestly, our first discovery is pretty much the definition of, “a blind hog will find an acorn every once in a while“. During Amy’s and Sanaa’s first day of discovery in 2012, Sanaa came up with the term ‘ocean’ for the large, open areas of lava that are virtually devoid of trees. Because the ocean as a whole can be considered a kind of desert, we found that term ‘ocean’ was correct: this part of the lava field truly resembled a desert. Thus, over the course of our fieldwork, the first verse and drifting characteristics of A Horse with No Name came to mind. The heat was hot. There were plants and birds and rocks and things. Oh yeah, there were a few rocks.
Together we learned that it was on the margins of these oceans that we could find what appeared to be ancient wood. It wasn’t until the penultimate day, however, that we had any sense of what we had accomplished.
Being 5 days in and having collected ~150 pieces of deadwood, we were all a bit burnt, literally and figuratively. Though we had sunscreen and hats, it wasn’t quite enough. We all looked a bit beety. We were also running on fumes. Constantly hiking on jumbled and sharp pieces of lava jars the body and mind. So, on Day 5 we set out for a low-pressure ‘cleanup’ of the lava field. Almost anything we collected that day would be bonus material.
We decided to head towards some of the sample locations from 2010 to see if we could find some of the oldest pieces. Many of the oldest pine cross-sections from 2010 were not GPS’ed due to time, energy, and the afterthought nature of that collection. So, on Day 5 in 2012 we wandering an area we mostly missed in 2012 while at the same time trying to recollect the hazy afternoon in 2010.
About 45 minutes to an hour in, we had our first success. We re-discovered ‘The Logo Tree’. While the day on the lava field in 2010 is still very hazy in my mind (due to my state of being in day 3 of undiagnosed and untreated tonsillitis), the sharpest memory of that day is The Logo Tree.
In 2010 The Logo Tree symbolized the potential for this site. We had spotted some Siberian pine trees, a species I did not see during my first brief visit to this site in 1999 with Gordon Jacoby, Baatarbileg Nachin, and Oyunsanaa (Sanaa) Byambasuren. This tree, though dead, captures many of the characteristics of old trees (charismatic megaflora) while also having the weathered, ‘stressed’ form of trees living on the edge of survival. These trees are often the ones tree-ring scientists use to reconstruct past climate. The Logo Tree screamed, “I, and many other pines like me, are ancient. You might better pay attention. This area could be filled with xylemite.”
So, it was with great joy that on Day 5 of 2012 The Logo Tree was re-discovered. Many picture were taken. Champagne corks were unleashed (in the form of taking the top off our water bottles and taking a swig of water). It certainly lifted me to a higher energy state.
We then spent much of the next few hours scouting for more samples from 2010 and passing through what can be considered a pine graveyard, an area filled with much deadwood and ancient, stunted pine trees.
A specific goal on Day 5 was to locate the oldest piece from 2010, a sample dating to the middle portion of the first millennium of the Common Era. Having not yet found it as the day was drawing to a close, we decided to narrowly focus on finding that piece. We wandered. We scratched our heads. We saw a horse with no name. And then…and then, we hit an area with signs of our past chainsaw work.
Could it be? Might that be The One?
Yes, it had to be. See, that sample, The Eldest of 2010, sits near my desk. It is within arm’s reach in case of impromptu lab tours. I know that sample. The Elder is a bit oval with a characteristic hole that makes it easier to carry or hold up with two fingers. This seemed to be it.
The joy and shock of this confirmation, of coming full circle, was that this log didn’t look as old or as weathered as many of the pieces we had collected over the prior 4.75 days. It didn’t look exceptional. It nearby cousin, cut 2/3rds of the up a dead stem, was equally unimpressive. Yet, The Elder’s cousin dates to the late-1200s.
This particular re-discovery floated us for the remainder of the day and trip back to Ulaanbaatar. We cannot yet say with any certainty, but it seems we really hit our research goal. In fact, we are now concerned that we might have some pieces so old that they will not date – they might actually predate any long chronology we might build from this site. But, if this is a problem, we wish this kind of problem to all of our colleagues.
Now, to some scenes from the field:
*No living trees were harmed in the creation of this post