Tag: Arctic

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What is happening to arctic lakes and why should we care?

by Mingzhen Zhang

Arctic temperatures are warming more than twice as fast as the global average [1, 2], causing permafrost thaw, loss of ice and snow cover on land and over the sea. Moreover, feedbacks from these changes aggravate global warming; the phenomenon is termed Arctic amplification. These changes attract increasing public attention, which is centered at the shrinking ice-cover over the ocean, the melting ice sheets and glaciers and thawing permafrost. Increasing research interest, however, is devoted to studying arctic lakes, which make up 25% of the world’s laketotal and cover up to 50% of the Arctic terrestrial landscape [3, 4]. For the public, the nature and importance of arctic lakes has remained vague. In this post I will try to elucidate some facts based on my own experiences.

Arctic lakes make up 25% of the world’s lakes and cover up to 50% of the arctic terrestrial landscape

  1. The uniqueness of arctic lakes

Before I planned to move to Finland for my doctoral research, “arctic lakes” were just two simple words for me. I only knew that these lakes were within the Arctic Circle. (Now I also know that anything northwards the Arctic Circle is only one definition of “arctic”.) Although I had some research experience on eutrophic Chinese lakes from my Master’s program, I felt unfamiliar with arctic lakes, which are significantly different from urban lakes I investigated previously. First, in terms of physical and chemical characteristics, urban lakes usually keep relatively stable states over the year, occasionally fluctuating with extreme weather events. In contrast, due to the pronounced climate, changing snow and ice cover, and differences in size, elevation, morphometry and ways of formation, arctic lakes experience a range of seasonal fluctuations in temperature, light availability and water quality [3]. Second, considering biological communities and production, urban lakes have higher species diversity involving all kinds of bacteria, phytoplankton, zooplankton, benthic species, fish and macrophytes, together with overall high primary productivity (dense algal blooms), compared to arctic lakes which are generally characterized by few species and low productivity [5]. The above-mentioned general characteristics of arctic lakes usually refer to lakes with clear water. However, arctic lake scenery is highly variable (Fig. 1). There are thermokarst lakes formed due to local permafrost degradation, and meltwater lakes, receiving glacial runoff with large amounts of suspended silt, and their water properties are very different from the clear-water lakes. Majority of the dozens of different ways for lake formation are presented in the Arctic, giving rise to the unique and diverse properties of arctic lakes, many of which remain unstudied. Arctic freshwater ecosystems provide services for arctic people and fauna. They are also important for global biodiversity, energy balance and carbon budget, all of which are rapidly changing due to climate warming.

Figure 1. A variety of lakes in northernmost Finland. (a) Lake Saanajärvi at the altitude of 679 meters. (b) A lake surrounded by mountain birch forest at the altitude of 553 m. (c) Lake Kilpisjärvi at the altitude of 473 m. (d) An arctic lake without the official name at the altitude of 1009 m. (e) Lake Jeahkatslampi at the altitude of 930 m. (f) Lake Bahtasgohpejavri at the altitude of 776 m. Photos courtesy of Jan Weckström (a, c, d, e) and  Maija Heikkilä (b, f), Environmental Change Research Unit.

2. The impact of climate change on arctic lakes

Climate change has a multitude of direct and indirect effects on arctic lake ecosystems. Changes in air temperatures, wind and precipitation patterns affect the structure, function and biodiversity of lakes, but so do changes in freshwater, nutrient and sediment inputs from lake catchment areas. First, continuously increasing air temperatures induce increasing lake water temperatures, which can change the thermal regimes of lakes, such as variation in mixing and stratification patterns. Consequently, many biogeochemical and biological processes and species composition of the lakes are affected [6]. Second, glacier retreat and permafrost thaw lead to more nutrients, organic matter and silt flowing into lakes, potentially modifying nutrient and light conditions in the oligotrophic, clear arctic lakes and resulting in higher primary production in summer and emerging new species [3]. In addition, climate change directly affects lake ice cover. One of the earliest observed impacts of climate warming was based on the loss of freshwater ice [7]. Research evidence demonstrates later lake ice-on and earlier ice-off dates, leading to shorter annual durations of ice cover and thus changes in lake ecology [8, 9]. Although there are many factors (e.g., air temperature, wind speed, snow thickness, solar radiation) that can affect ice formation and melt in shallow and deep lakes, air temperature is the key driver [10]. Thus, lake ice phenology can serve as a useful indicator of late autumn and early spring climate change in a regional scale [11]. Additionally, lake ice plays a vital role in socio-economy such as ice roads, transportation, cultural recreation and tourism [12]. Understanding the freeze-thaw cycles of lake ice and their effects on arctic ecosystems including the human, can promote the safety of the region on many levels.

Research evidence demonstrates later ice-on and earlier ice-off dates of arctic lakes

3. Arctic lakes and past climate reconstruction

Human societies have had an increasing influence on global climate over the past centuries. Understanding natural climate changes and ecosystem responses is quintessential in preparing for future. As I mentioned above, arctic lakes are sensible to climate variability. What is more, their bottom mud or sediments, serve as a chronicle of changes over the past millennia. Lake sediments archive variations in biological and physical conditions and provide a unique temporal record of climatic change [13]. Many indicators, such as microfossils (diatoms, chrysophycean cysts, chironomids, cladocerans), biogeochemical markers (elemental and isotopic geochemistry, plant pigments, plant lipids), mineral magnetic analyses, and various sediment indices (the accumulation rates of organic carbon, nutrients, contaminants, etc.) have been developed to analyze the shifts in lake physical, chemical and ecosystem qualities [13, 14]. Therefore, a comprehensive arctic paleoclimate data network, covering various lake types in various settings, is necessary for reliable assessments of past, present and future climate patterns.

Circumpolar regions might seem isolated from the rest of the planet, but in reality, they play an integral role in the global climate system. Furthermore, these regions have been inhabited by arctic peoples for thousands of years [15], and experienced significant environmental transitions due to climate changes and human impacts. Improved understanding of northern nature and lakes and their responses to environmental changes will contribute to the sustainable development of the Arctic. It is a great honor for me to have an opportunity to participate in this research, and I hope to contribute to elevated knowledge of fascinating arctic lakes.

Mingzhen is a doctoral researcher whose research focuses on arctic lakes in northernmost Finland.

Reference

  1. Meredith M, et al. 2019. In: IPCC Special Report on the Ocean and Cryosphere in a Changing Climate. Cambridge University Press, Cambridge, UK and New York, NY, USA, 2019. 203-320. https://doi.org/10.1017/9781009157964.005.
  2. Moon TA, et al. (2021). Arctic Report Card 2021.  https://www.arctic.noaa.gov/Report-Card/Report-Card-2021
  3. Jeppesen E, et al., 2020. Ecology of Arctic Lakes and Ponds. In Thomas, DN (ed): Arctic Ecology, pp. 159-180.  https://doi.org/10.1002/9781118846582.ch7
  4. Muster S, et al., 2017. PeRL: a circum-Arctic permafrost region pond and lake database. Earth System Science Data 9: 317–348. https://doi.org/10.5194/essd-9-317-2017
  5. Christoffersen KS, et al., 2008. Food-web relationships and community structures in high-latitude lakes. In Vincent WF & Laybourn-Parry J (eds): Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems. DOI:10.1093/acprof:oso/9780199213887.003.0015
  6. Arvola L, et al., 2009. The Impact of the Changing Climate on the Thermal Characteristics of Lakes. In George, G (ed.): The Impact of Climate Change on European Lakes, 85-101. DOI: 10.1007/978-90-481-2945-4
  7. Walsh SE, et al., 1998. Global patterns of lake ice phenology and climate: Model simulations and observations. Journal of Geophysical Research: Atmospheres 103(D22): 28825-28837. DOI: 10.1029/98jd02275
  8. Magnuson JJ, et al., 2000. Historical Trends in Lake and River Ice Cover in the Northern Hemisphere. Science 289: 1743-1746. DOI: 10.1126/science.289.5485.1743
  9. Benson BJ, et al., 2012. Extreme events, trends, and variability in Northern Hemisphere lake-ice phenology (1855–2005). Climatic Change 112: 299–323. DOI: 10.1007/s10584-011-0212-8
  10. Kirillin G & Leppäranta M, 2021. Lake Ice Formation and Melt. Under-Ice Dynamics. Reference Module in Earth Systems and Environmental Sciences,
    Elsevier. https://doi.org/10.1016/B978-0-12-819166-8.00003-7
  11. Hodgkins GA., et al., 2002. Historical changes in lake ice-out dates as indicators of climate change in New England, 1850-2000. International Journal of Climatology 22: 1819-1827. DOI: 10.1002/joc.857
  12. Arp CD, 2019. Ice roads through lake-rich Arctic watersheds: Integrating climate uncertainty and freshwater habitat responses into adaptive management Arctic, Antarctic, and Alpine Research 51, 9-23. https://doi.org/10.1080/15230430.2018.1560839
  13. Korhola A, et al., 2002. A multi-proxy analysis of climate impacts on the recent development of subarctic Lake Saanajärvi in Finnish Lapland. Journal of Paleolimnology 28: 59-77. https://doi.org/10.1023/A:1020371902214
  14. Lehnherr I, et al., 2018. The world’s largest High Arctic lake responds rapidly to climate warming. Nature Communications 9: 1290. https://doi.org/10.1038/s41467-018-03685-z
  15. Kotlyakov VM, et al., (eds.) 2017.  Human Colonization of the Arctic: The Interaction Between Early Migration and the Paleoenvironment. 530 pp. https://doi.org/10.1016/B978-0-12-813532-7.01001-9
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The large-scale approach – my experience with open databanks

by Ana Lúcia Lindroth Dauner

When someone tells me that the climate is changing, I always think “Okay, but how? Where is it changing? Is it changing in the same way everywhere? How do the changes affect ecosystems and human societies?” In order to answer these types of questions, an comprehensive set of adequate, good quality data is essential. The challenge with these large-scale questions is that you cannot collect all this data within your research project – or even within your lifetime of research. For example, I am currently investigating how past changes in Arctic sea-ice cover affected lake ecosystems in the northern polar region. I cannot simply go out and collect samples from every lake in and around the Arctic.

The sampling of sedimentary records usually requires complex and expensive expeditions, with a team of scientists, especially if the sampling site is remote. For example, some lakes are located far away from roadways and electricity; so proper vehicles and carrying generators to the field are needed. After sediment cores are recovered, the sediment dating and analytical laboratory work is expensive, laborious and time-consuming. In order to analyse only one sediment record sliced into approximately 100 samples, it took me around 4 months of direct laboratory work during my PhD. So, imagine how long it would take for an army of PhD students to analyse, for example, one record from one hundred different lakes! And, even if I could sample one lake in each continent, it would not be representative of the whole region. Several factors affect the organic matter production within a lake, such as lake elevation, hydrology, the type of catchment vegetation and the distance from the coast (termed “oceanity” or “continentality”) that affects the temperature and precipitation patterns. These regional and local factors vary greatly within a large region. That being said, what is the solution? Well, one option is to use data collected by other researchers!

In order to analyse only one sediment record sliced into approximately 100 samples, it took me around four months of direct laboratory work during my PhD. So, imagine how long it would take for an army of PhD students to analyse, for example, one record from one hundred different lakes!

Even though the northern polar region is remote, high-quality scientific research has been performed in these regions for decades, and several of the published datasets are available in online databases such as Pangaea1, NOAA/WDS for Paleoclimatology2 and Neotoma Paleoecology Database3. They make available proxy information from lake sediment cores, some of which could be suitable for inferring past changes in lake production, such as the percentage of organic matter or the number of microalgal fossils. All I need to do is to download these datasets, combine the information and answer my question, right? Well, it would be fantastic if it were that fast and easy! However, that is rarely the case.

First of all, there are more than just one central database. It was almost like looking for a specific author within several libraries. Then, there was the challenge of carefully choosing the search words. If I simply looked for “lakes” in a northern hemisphere database, I received thousands of results, most of them lacking the information I was looking for. If I used too specific search words, such as “biogenic opal flux”, on the other hand, I got just a few data sets and might have missed out on valuable information. There is no magic formula here, and as generally in research, for big data science too, perseverance and patience are the keywords. One last bump on the road in the searching process was that many published datasets were not made available online. Although nowadays several journals and universities require authors to make their data openly available in one of the online databases, sometimes even before publishing the manuscript, significant amount of good datasets remain behind the authors. So, in many cases, even big data searching involves basic human connection: writing the authors asking for their data for a specific purpose, and hopefully waiting for them to respond positively.

After searching for proper databases through adequate search words, I (luckily!) found myself with lots of datasets. Yet after all that, I needed to tackle the main challenge: keeping things in order! As someone who struggles with orderliness, it was especially important to find a way to keep my research organized! Every sediment record received a unique ID and I created a spreadsheet where all the information was combined according to this unique ID. This way, I can easily check the information related to a specific record, such as the lake size or if this record has microalgae data. Another important step was to standardize the format of the datasets, so I can work with them in a more efficient way. Only after that, it was possible to start cleaning the data. After looking into various databases (or libraries), it is common to have replicas, i.e., the same data set was found in more than one library. So, they needed to be removed and the remaining data problems, such as missing data or inadequate temporal resolution and different units (e.g. temperatures in Celsius or Fahrenheit), fixed. All these filtering, cleaning and tidying steps are extremely important but can take a long time, so planning accordingly is vital!

Enough of the challenges: you want to know what happened to my data digging experiment, right? At this point, I am still dealing with the above-mentioned steps! Patiently and gradually, I will be able to proceed to the next steps: appropriate analyses and graphs to combine and compare all the information in a way that robust answers to my questions, so my compilation is not, well, “just a lot of data”. As someone who is still in the searching, cleaning and tidying step, I increasingly value the studies and the researchers that were able to extract information from several previous studies to answer a new and exciting research question.

Also, from what I have for now, I think we need more field work and lake records! Most of the studies in the online databases were performed in coastal regions and mainly in Alaska, Fennoscandia and coastal Greenland, but data from the Arctic Russia, some parts of Canada and more continental regions are still lacking. Moreover, analytical and chronological techniques and thus data resolution and proxy variety have progressed in time. In any case, I believe that the collection of published data I have compiled will be enough to start answering some the intriguing large-scale questions. Stay tuned!

_______

Ana Lúcia is a postdoctoral researcher who strangely finds joy in the crashing R.

Explore the amazing paleo data sets:

1 https://www.pangaea.de/

2 https://www.ncdc.noaa.gov/paleo-search/

3 https://www.neotomadb.org/

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How to tend to your research (and motivation) during a pandemic: our view of the past year

by Lilia Orozco

It is almost a year since the COVID-19 pandemic spread globally, but the final repercussions for science will be realized in the years to come. Travel restrictions canceled most planned fieldwork, conferences and research visits, while social distancing changed the way we communicate, plan our activities and interact. How we, as a scientific community, confront the new circumstances has been a subject of conversation from the beginning (1-3).

On March 16, 2020, the Universities in Finland were shut down. Since then, our research group has been managing projects and thesis work from a new angle. I started my PhD research on past northern lake ecosystems in November 2020, amid the exceptional situation. I was prepared for the home office and the uncertainty in field and lab work plans. It helped me to focus on what I can do rather than what I cannot. A pandemic-suited mindset might be easy to set at the beginning of a project, but how has it been for those who made their plans prior to COVID-19? I asked our group.

Most of us had to make arrangements. Maxime Courroux, a Master’s student studying sub-arctic lakes, explains:

“A Master’s thesis is a relatively short project. But within a year, I had to change my topic, re-plan my field schedule, and manage to finish everything on time. While this wasn’t a walk in the park, the shared struggle with peers has led to a lot of support. Nothing went as expected, but it was still fun.”

For Tiia Luostarinen, PhD candidate studying microscopic sea-ice organisms, the closure of universities, and even countries, meant leaving laboratory analyses at a short notice.

“When the pandemic started to spread in Europe, I was in Denmark for some lab work but was supposed to travel back home in a couple of days anyway. When the Danish government announced that they are closing their borders, I changed my flights and returned to Finland. It was hard to miss saying proper goodbyes to everyone in Copenhagen.”

Despite the boost in discoveries and publications about and COVID-19 (4, 5) in the past year, natural sciences looking into equally topical global challenges, e.g. climate change and environmental degradation, have not had that luck (6). Restrictions have forced scientists to re-think their projects and plans. The University of Helsinki closed its facilities, but we have been able to carry out essential lab work under strict regulations.

Maija Heikkilä, the principal investigator of both currently active Academy of Finland funded projects, faces these circumstances head-on:

“Getting a research project funded is always a thrill, and in all honesty, having another research project launched during the global pandemic was equally exciting. There are new questions to be answered, new people to be hired, and due to the pandemic, new implementation plans to be made. This is much easier at the very beginning of the project than in the middle of it, but we have managed all our work rather brilliantly. Our University has been strict but prioritized science where possible.”

The University of Helsinki allowed a field trip on our Master’s level course Past environmental change in January 2021, because it was held outdoors with safe distances. Senior researcher Jan Weckström giving a demonstration on sampling methods. Maxime and Lilia were teaching assistants.

Collaboration and exchange of ideas are focal to any research. The social restrictions have forced us to use different technologies (who could have imagined the now-so-routine ZOOM coffees a year ago!). The new ways of communicating are not always ideal, in particular if you have just arrived in a new country. This is the experience of Ana Lúcia Lindroth Dauner, the new postdoc researcher in the team working on integrating and combining paleoecological data. Ana has not even met everybody in the group in person.

“Besides conciliating the time between academic and domestic work, the main issue I have had in starting to work on a project in the midst of the pandemic is the lack of personal contact. The pandemic makes it difficult to get to know new people and, therefore, to share thoughts and ideas.”

Ana shared a view to her home office.

We have all coped with the situation that started one year ago in different ways. We have had to find a balance between life and work, transform our homes into offices, and accept new realities that we did not expect. For Master’s student Meri Mäkelä, whose thesis unravels past ecosystem changes in an arctic fjord, staying motivated has helped her finish her project.

“In February 2020 I definitely couldn’t predict that after a year I would still be finishing my Master’s thesis surrounded by the pandemic. No doubt that the pandemic has slowed down my thesis project, but to be honest, my enthusiasm to left no stone unturned should be blamed more. At least I have learned to make less overly optimistic timetables for my projects to come – I hope.”

Confinement is not ideal for everyone, but after a year of this reality, we have modified our practices. Tiia has learned to appreciate the time at home.

“If you would have asked me if I liked working from home a year ago, the answer would’ve been a definite no. But this situation has at least taught me to appreciate the quietness and flexibility of working from home. And obviously, the better coffee.”

Like Tiia, Maija profits from the advantages of telecommuting and stays optimistic.

“The lack of commuting and traveling has brought a new sense of tranquility to daily work tasks and challenged me to develop new ways for team building. I am positive and face challenges that are much smaller than the responsibility of an individual to take part in fighting the global pandemic.”

Indeed, while we look forward to resuming fieldwork and in-person interaction as soon as it is safe, it is good to keep things in perspective. Despite our differing experiences and perspectives from the past year, everyone has surely mastered one thing – to adapt.

—-

Lilia Orozco is a PhD student who celebrates picking the first fossil remains in her lake sediment samples.

List of references:

  1. Clay RA (2020, March 19). Conducting research during the COVID-19 pandemic. http://www.apa.org/news/apa/2020/03/conducting-research-covid-19
  2. Pain E (2020, April 17) How early-career scientists are coping with COVID-19 challenges and fears. Science Careers.
  3. Kupferschmidt K (2020, February 26). A completely new culture of doing research. Coronavirus outbreak changes how scientists communicate. Science News. 
  4. Science in the Wake of the Pandemic: How Will COVID-19 Change the Way We Do Research? (2020). Molecular cell 79:9–10. https://doi.org/10.1016/j.molcel.2020.06.024
  5. Palayew A, Norgaard O, Safreed-Harmon K, Andersen TH, Rasmussen LN, Lazarus JV (2020). Pandemic publishing poses a new COVID-19 challenge. Nature Human Behaviour 4:666-9. https://doi.org/10.1038/s41562-020-0911-0
  6. Bian SX, Lin E (2020). Competing with a pandemic: Trends in research design in a time of Covid-19. Plos One 15:e0238831. https://doi.org/10.1371/journal.pone.0238831
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Brief overview of current projects

Beyond the shore: sea-ice change and lake ecosystems in the Arctic (SLEET)

The land and the sea are quintessentially tied together via the global hydrological cycle and atmospheric circulation patterns, yet significant disconnect persists in both research and management of land and marine ecosystems. Future intensification of the hydrological cycle in the Arctic and the increased interaction of the sea surface with the atmosphere will further enhance ecosystem interaction across the land-sea boundaries. The overarching objective of this project is to develop an understanding of the natural, long-term coupling of arctic sea-ice cover and lake ecosystem functioning on adjacent land in complementary spatial scales. The project will explore the atmospheric mechanism of this link by reconstructing moisture balance trends and probing their linkages to the quantity and quality of production. (Academy of Finland 2020-2024)

Arctic sea-ice proxies: from seasonal processes to improved reconstructions

Sea-ice decline is one of the most striking consequences of recent climate-driven changes in the Arctic. The short observational time series and current climate models are inadequate in explaining the natural variation and foreseeing responses of arctic marine ecosystems, highlighting the urgent need to exploit natural archives (proxies). Protists abundantly stored in the seafloor of the Arctic Ocean are widely applied proxies for past sea-ice reconstruction, notwithstanding that little is known of their relationships to the ice ecosystem. This project will investigate seasonal processes that result in the formation of proxy archives and apply this knowledge in ecosystem modelling and reconstruction of pre-anthropogenic sea-ice conditions. The results will improve our understanding of the seasonal behaviour of arctic marine ecosystems in the long term. (Academy of Finland 2016-2022)

CAPTURE Consortium Work Package 3: Past and present lake carbon dynamics

The Arctic environment is undergoing marked changes in climate conditions and terrestrial feedbacks that are prone to investigation under the multidisciplinary framework of CAPTURE. The interactions among climate, C and Arctic ecosystems are complex, and there are substantial risks of unexpected feedbacks and rapid transformations. One of the main originalities of the CAPTURE consortium is assessing the C processes in the Arctic across spatial and temporal scales, in order to advance our understanding of C dynamics, climate variability and the risks of unwelcome C-cycle feedbacks.

WP3 investigates the quantity and quality of lake C in present conditions and over the major climatic fluctuations of the late Holocene. In collaboration with WPs 1, 2, and 4, WP3 will assess the lateral C flow between terrestrial and aquatic ecosystems. C quality will be of special interest, since parsing contributions of C sources are essential to understanding lake aquatic C cycling and burial efficiency WP3 focuses on lake sediment records for three principal reasons. First, while many long-term records signify the role of lake
sediments as global C sink, they consider average C accumulation over long time periods and are hence not adequate for observing responses of C burial to rapid climate changes. Second, the role of changing C sources over past climate intervals and the long-term persistence of C sink are largely unknown. Third, most studies focus on temperate and boreal lakes, while contrasting controls of C cycling are at play in the Arctic. (Academy of Finland 2016-2020)

Author: Maija Heikkilä