Anthropogenic eutrophication, acidification, and climate change Interest in paleolimnology eventually shifted from esoteric questions of lake ontogeny to applied investigations of human impact. Torgny Wiederholm and Bill Warwick, for example, used chironomid fossils to assess the impacts of increased, human-caused nutrient loading (anthropogenic eutrophication) on lake communities. Their studies revealed pronounced changes in the bottom fauna of North American and European lakes as a consequence of severe oxygen depletion. From 1980 to 1990 the primary focus of paleolimnologists  efforts shifted to understanding the role of human impacts (e.g., acid rain) versus natural processes (e.g., soil leaching) as drivers of pH change in northern lakes.Battarbee, R. W. 1984. Diatom analysis and the acidification of lakes. Philosophical Transactions of the Royal Society of London 305: 451–477. The pH-sensitivity of diatom communities had been recognized as early as the 1930s, when Friedrich Hustedt developed a classification for diatoms  based on their apparent pH preferences. Gunnar Nygaard subsequently developed a series of diatom pH indices. By calibrating these indices to pH, Jouko Meriläinen introduced the first diatom-pH transfer function. Using diatom and chrysophyte fossil records, research groups were able to clearly demonstrate that many northern lakes had rapidly acidified in consequence of increased industrialization and emissions . Although lakes also showed a tendency to acidify slightly during their early (late-glacial) history, the pH of most lakes had remained stable for several thousand years prior to their recent human-driven acidification. In recent years paleolimnologists have recognized that climate is a dominant force in aquatic ecosystem processes, and have begun to use lacustrine records to reconstruct paleoclimates. Sensitive records of climate change have been developed from a variety of indicators, including, for example, paleotemperature reconstructions derived from chironomid fossils, and paleosalinity records inferred from diatoms. Recent studies in the Arctic show that changes in biodiversity are largely due to arctic warming rather than other associated factors  such as human alteration and acidification. In the Himalayan water bodies are not only affected by the anthropogenic disturbances but also impacted by the different types of pollutants that are transferred to the area from a longer distance . Therefore, it is vital to understand all the associated factors acting on the aquatic biodiversity, while analyzing the impact of climate change over the years  with the help of lake sediments.Sharma, C.M; Sharma, S; Gurung, S; Bajracharya, R.M; Jüttner, I; Pradhan, N.S (2009). "Global Climatic Change and High Altitude Lakes: Impacts on Aquatic Biodiversity and Pollution Status". Natural Resources Management: Reviews and Research in the Himalayan Watersheds. 44 (977): 103–122. It is also important to consider that the impact and intensity of climate-change effects varies depending on an ecosystem's sensitivity to change  when assessing climate change from a paleolimnological perspective.
Anthropogenic eutrophication, acidification, and climate change Interest in paleolimnology eventually shifted from esoteric questions of lake ontogeny to applied investigations of human impact. Torgny Wiederholm and Bill Warwick, for example, used chironomid fossils to assess the impact of increased, human-caused nutrient loading (anthropogenic eutrophication) on lake communities. Their studies revealed pronounced changes in the bottom fauna of North American and European lakes as a consequence of severe oxygen depletion. From 1980 to 1990 the primary focus of paleolimnologists ' efforts shifted to understanding the impact human activity had (e.g., acid rain) versus natural processes (e.g., soil leaching) as drivers of pH change in northern lakes.Battarbee, R. W. 1984. Diatom analysis and the acidification of lakes. Philosophical Transactions of the Royal Society of London 305: 451–477. The pH-sensitivity of diatom communities had been recognized as early as the 1930s, when Friedrich Hustedt developed a classification for diatoms , based on their apparent pH preferences. Gunnar Nygaard subsequently developed a series of diatom pH indices. By calibrating these indices to pH, Jouko Meriläinen introduced the first diatom-pH transfer function. Using diatom and chrysophyte fossil records, research groups were able to clearly demonstrate that many northern lakes had rapidly acidified in consequence of increased industrialization . Although lakes also showed a tendency to acidify slightly during their early (late-glacial) history, the pH of most lakes had remained stable for several thousand years prior to their recent human-driven acidification. In recent years paleolimnologists have recognized that climate is a dominant force in aquatic ecosystem processes, and have begun to use lacustrine records to reconstruct paleoclimates. Detailed records of historical climate change have been developed from a variety of indicators, including, for example, paleotemperature reconstructions derived from chironomid fossils, and paleosalinity records inferred from diatoms. Recent studies in the Arctic show that changes in biodiversity are largely due to warming, rather than other associated factors , such as human alteration and acidification. In the Himalayas, bodies of water are not only affected by the anthropogenic disturbances but also impacted by the different types of pollutants that are transferred to the area from afar . Therefore, it is vital to understand all the associated factors acting on aquatic biodiversity, while analyzing the impact of climate change over the years , with the help of lake sediments.Sharma, C.M; Sharma, S; Gurung, S; Bajracharya, R.M; Jüttner, I; Pradhan, N.S (2009). "Global Climatic Change and High Altitude Lakes: Impacts on Aquatic Biodiversity and Pollution Status". Natural Resources Management: Reviews and Research in the Himalayan Watersheds. 44 (977): 103–122. It is also important to consider that the impact of climate-change varies depending on an ecosystem's sensitivity to change , when assessing climate change from a paleolimnological perspective.
R
impacts
impact
A
'
R
role of human impacts
impact human activity had
A
,
D
and emissions
R
Sensitive records of
Detailed records of historical
R
arctic warming
warming,
A
,
R
Himalayan water bodies
Himalayas, bodies of water
R
a longer distance
afar
D
the
A
,
D
and intensity
D
effects
A
,