From The University of Copenhagen [Københavns Universitet](DK) Via “Science Alert (AU)” : “Small Lakes Keep Growing Across The Planet And It’s a Serious Problem” 

From The University of Copenhagen [Københavns Universitet](DK)

Via

ScienceAlert

“Science Alert (AU)”

12.5.22
David Nield

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Small Lake From Above (Vitali Kasporski/Getty Images)

A new study has revealed that small lakes on Earth have expanded considerably over the last four decades – a worrying development, considering the amount of greenhouse gases freshwater reservoirs emit.

Between 1984 and 2019, global lake surfaces increased in size by more than 46,000 square kilometers (17,761 square miles), researchers say. That’s slightly more than the area covered by Denmark.

Carbon dioxide, methane, nitrous oxide, and other gasses are constantly produced from lakes, because of the bacteria and fungi feeding at the bottom of the water, snacking on dead plants and animals that have drifted down to the lake floor.

In total, this lake spread equates to an annual increase of carbon emissions in the region of 4.8 teragrams (or trillion grams) of CO2 – which to continue the country comparisons equals the increase in CO2 emitted by the whole of the UK in 2012.

“There have been major and rapid changes with lakes in recent decades that affect greenhouse gas accounts, as well as ecosystems and access to water resources,” says terrestrial ecologist Jing Tang, from the University of Copenhagen in Denmark.

“Among other things, our newfound knowledge of the extent and dynamics of lakes allows us to better calculate their potential carbon emissions.”

The researchers used a combination of satellite imagery and deep learning algorithms to make their assessments on lake coverage. A total of 3.4 million lakes were logged in total.

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Lake coverage across the globe, over two time periods spanning 1984-2019. (Pi et al., Nature Communications, 2022).

Smaller lakes (less than one square kilometer or 0.39 square miles) are so important to the calculation of greenhouse gases because they produce a high volume of emissions relative to their size, the team says.

These less expansive bodies of water account for just 15 percent of the total lake coverage, yet are responsible for a 45 percent of the increase in carbon dioxide output and 59 percent of the increase in methane emissions across the 1984 to 2019 period.

“Small lakes emit a disproportionate amount of greenhouse gasses because they typically accumulate more organic matter, which is converted into gasses,” says Tang. “And also, because they are often shallow. This makes it easier for gasses to reach the surface and up into the atmosphere.”

“At the same time, small lakes are much more sensitive to changes in climate and weather, as well as to human disturbances. As a result, their sizes and water chemistry fluctuate greatly. Thus, while it is important to identify and map them, it is also more demanding. Fortunately, we’ve been able to do just that.”

More than half of the increase in lake coverage over the study period is due to human activity, the researchers say – essentially, newly constructed reservoirs. The rest is mainly due to melting glaciers and thawing permafrost, caused by the warming of our planet.

The researchers are hoping that their data will prove useful for future climate models, with a significant chunk of greenhouse gasses potentially coming from lake surfaces as more melting and warming continues.

“Furthermore, the dataset can be used to make better estimates of water resources in freshwater lakes and to better assess the risk of flooding, as well as for better lake management – because lake area impacts biodiversity too,” says Tang.

The research has been published in Nature Communications.
See the science paper for instructive material with more images.

Fig. 1: Spatial distribution of global lakes.
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Lakes with maximum surface area >0.03 km^2 were mapped, showing a lake count (total number of lakes) and b lake area density (total lake area/grid area) per 1° × 1° grid cell. The longitudinal and latitudinal lake profiles summarizing (by 1°) the lake count and lake area are shown on c and d. Statistics for small (100 km^2) lakes are presented within each panel of a and b.

Fig. 2: Lake area changes across different periods (1980–1990s, 2000s, and 2010s).
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Data were aggregated into 1° × 1° grid cells. The gray areas indicate regions with insufficient satellite coverage in the early periods; these regions were excluded from the analysis. Within each panel, the changes within and outside the glacial or permafrost regions are also presented, and the contributions of natural lakes and reservoirs are illustrated.

See the full article here .

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The University of Copenhagen [Københavns Universitet] (DK)] is a public research university in Copenhagen, Denmark. Founded in 1479, the University of Copenhagen is the second-oldest university in Scandinavia, and ranks as one of the top universities in the Nordic countries and Europe.

Its establishment sanctioned by Pope Sixtus IV, the University of Copenhagen was founded by Christian I of Denmark as a Catholic teaching institution with a predominantly theological focus. After 1537, it became a Lutheran seminary under King Christian III. Up until the 18th century, the university was primarily concerned with educating clergymen. Through various reforms in the 18th and 19th century, the University of Copenhagen was transformed into a modern, secular university, with science and the humanities replacing theology as the main subjects studied and taught.

The University of Copenhagen consists of six different faculties, with teaching taking place in its four distinct campuses, all situated in Copenhagen. The university operates 36 different departments and 122 separate research centres in Copenhagen, as well as a number of museums and botanical gardens in and outside the Danish capital. The University of Copenhagen also owns and operates multiple research stations around Denmark, with two additional ones located in Greenland. Additionally, The Faculty of Health and Medical Sciences and the public hospitals of the Capital and Zealand Region of Denmark constitute the conglomerate Copenhagen University Hospital.

A number of prominent scientific theories and schools of thought are namesakes of the University of Copenhagen. The famous Copenhagen Interpretation of quantum mechanics was conceived at the Niels Bohr Institute [Niels Bohr Institutet](DK), which is part of the university. The Department of Political Science birthed the Copenhagen School of Security Studies which is also named after the university. Others include the Copenhagen School of Theology and the Copenhagen School of Linguistics.

As of October 2020, 39 Nobel laureates and 1 Turing Award laureate have been affiliated with the University of Copenhagen as students, alumni or faculty. Alumni include one president of the United Nations General Assembly and at least 24 prime ministers of Denmark. The University of Copenhagen fosters entrepreneurship, and between 5 and 6 start-ups are founded by students, alumni or faculty members each week.

History

The university is a member of the International Alliance of Research Universities (IARU), along with University of Cambridge (UK), Yale University, The Australian National University (AU), and University of California, Berkeley, amongst others. The 2016 Academic Ranking of World Universities ranks the University of Copenhagen as the best university in Scandinavia and 30th in the world, the 2016-2017 Times Higher Education World University Rankings as 120th in the world, and the 2016-2017 QS World University Rankings as 68th in the world. The university has had 9 alumni become Nobel laureates and has produced one Turing Award recipient.

The University of Copenhagen was founded in 1479 and is the oldest university in Denmark. In 1474, Christian I of Denmark journeyed to Rome to visit Pope Sixtus IV, whom Christian I hoped to persuade into issuing a papal bull permitting the establishment of university in Denmark. Christian I failed to persuade the pope to issue the bull however and the king returned to Denmark the same year empty-handed. In 1475 Christian I’s wife Dorothea of Brandenburg Queen of Denmark made the same journey to Rome as her husband did a year before. Unlike Christian I Dorothea managed to persuade Pope Sixtus IV into issuing the papal bull. On the 19th of June, 1475 Pope Sixtus IV issued an official papal bull permitting the establishment of what was to become the University of Copenhagen.

On the 4th of October, 1478 Christian I of Denmark issued a royal decree by which he officially established the University of Copenhagen. In this decree Christian I set down the rules and laws governing the university. The royal decree elected magistar Peder Albertsen as vice chancellor of the university and the task was his to employ various learned scholars at the new university and thereby establish its first four faculties: theology; law; medicine; and philosophy. The royal decree made the University of Copenhagen enjoy royal patronage from its very beginning. Furthermore, the university was explicitly established as an autonomous institution giving it a great degree of juridical freedom. As such the University of Copenhagen was to be administered without royal interference and it was not subject to the usual laws governing the Danish people.

The University of Copenhagen was closed by the Church in 1531 to stop the spread of Protestantism and re-established in 1537 by King Christian III after the Lutheran Reformation and transformed into an evangelical-Lutheran seminary. Between 1675 and 1788 the university introduced the concept of degree examinations. An examination for theology was added in 1675 followed by law in 1736. By 1788 all faculties required an examination before they would issue a degree.

In 1807 the British Bombardment of Copenhagen destroyed most of the university’s buildings. By 1836 however the new main building of the university was inaugurated amid extensive building that continued until the end of the century. The University Library (now a part of the Royal Library); the Zoological Museum; the Geological Museum; the Botanic Garden with greenhouses; and the Technical College were also established during this period.

Between 1842 and 1850 the faculties at the university were restructured. Starting in 1842 the University Faculty of Medicine and the Academy of Surgeons merged to form the Faculty of Medical Science while in 1848 the Faculty of Law was reorganised and became the Faculty of Jurisprudence and Political Science. In 1850 the Faculty of Mathematics and Science was separated from the Faculty of Philosophy. In 1845 and 1862 Copenhagen co-hosted nordic student meetings with Lund University [Lunds universitet] (SE).

The first female student was enrolled at the university in 1877. The university underwent explosive growth between 1960 and 1980. The number of students rose from around 6,000 in 1960 to about 26,000 in 1980 with a correspondingly large growth in the number of employees. Buildings built during this time period include the new Zoological Museum; the Hans Christian Ørsted and August Krogh Institutes; the campus centre on Amager Island; and the Panum Institute.

The new university statute instituted in 1970 involved democratisation of the management of the university. It was modified in 1973 and subsequently applied to all higher education institutions in Denmark. The democratisation was later reversed with the 2003 university reforms. Further change in the structure of the university from 1990 to 1993 made a Bachelor’s degree programme mandatory in virtually all subjects.

Also in 1993 the law departments broke off from the Faculty of Social Sciences to form a separate Faculty of Law. In 1994 the University of Copenhagen designated environmental studies; north–south relations; and biotechnology as areas of special priority according to its new long-term plan. Starting in 1996 and continuing to the present the university planned new buildings including for the University of Copenhagen Faculty of Humanities at Amager (Ørestaden) along with a Biotechnology Centre. By 1999 the student population had grown to exceed 35,000 resulting in the university appointing additional professors and other personnel.

In 2003 the revised Danish university law removed faculty staff and students from the university decision process creating a top-down control structure that has been described as absolute monarchy since leaders are granted extensive powers while being appointed exclusively by higher levels in the organization.

In 2005 the Center for Health and Society (Center for Sundhed og Samfund – CSS) opened in central Copenhagen housing the Faculty of Social Sciences and Institute of Public Health which until then had been located in various places throughout the city. In May 2006 the university announced further plans to leave many of its old buildings in the inner city of Copenhagen- an area that has been home to the university for more than 500 years. The purpose of this has been to gather the university’s many departments and faculties on three larger campuses in order to create a bigger more concentrated and modern student environment with better teaching facilities as well as to save money on rent and maintenance of the old buildings. The concentration of facilities on larger campuses also allows for more inter-disciplinary cooperation. For example the Departments of Political Science and Sociology are now located in the same facilities at CSS and can pool resources more easily.

In January 2007 the University of Copenhagen merged with the Royal Veterinary and Agricultural University and the Danish University of Pharmaceutical Science. The two universities were converted into faculties under the University of Copenhagen and were renamed as the Faculty of Life Sciences and the Faculty of Pharmaceutical Sciences. In January 2012 the Faculty of Pharmaceutical Sciences and the veterinary third of the Faculty of Life Sciences merged with the Faculty of Health Sciences forming the Faculty of Health and Medical Sciences and the other two thirds of the Faculty of Life Sciences were merged into the Faculty of Science.

Cooperative agreements with other universities

The university cooperates with universities around the world. In January 2006, the University of Copenhagen entered into a partnership of ten top universities, along with the Australian National University (AU), Swiss Federal Institute of Technology in Zürich [ETH Zürich] [Eidgenössische Technische Hochschule Zürich](CH), The National University of Singapore [Universiti Nasional Singapura] (SG), Peking University [北京大学](CN), University of California Berkeley , University of Cambridge (UK), University of Oxford (UK), University of Tokyo {東京大学](JP) and Yale University. The partnership is referred to as the International Alliance of Research Universities (IARU).

The Department of Scandinavian Studies and Linguistics at University of Copenhagen signed a cooperation agreement with the Danish Royal School of Library and Information Science in 2009.