[MCN] 3 on climate impact on the state of the lakes

[Lance Olsen]

First, this related update:

World's biggest investors, in control of $41 trillion, attack fossil fuels  <https://news.google.com/articles/CBMic2h0dHBzOi8vdGhlaGlsbC5jb20vY2hhbmdpbmctYW1lcmljYS9zdXN0YWluYWJpbGl0eS9jbGltYXRlLWNoYW5nZS81NTgwMzEtd29ybGRzLWJpZ2dlc3QtaW52ZXN0b3JzLWluLWNvbnRyb2wtb2YtNDHSAXdodHRwczovL3RoZWhpbGwuY29tL2NoYW5naW5nLWFtZXJpY2Evc3VzdGFpbmFiaWxpdHkvY2xpbWF0ZS1jaGFuZ2UvNTU4MDMxLXdvcmxkcy1iaWdnZXN0LWludmVzdG9ycy1pbi1jb250cm9sLW9mLTQxP2FtcA?hl=en-US&gl=US&ceid=US%3Aen>
More than 400 investors, who collectively hold a third of the world's assets, are demanding governments end their support of fossil fuels and make significant strides in cutting carbon emissions in the next decade.

The Hill June 11, 2021

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NASA  December 15, 2015
Study: Climate change rapidly warming world's lakes

Opening paragraphs : Climate change is rapidly warming lakes around the world, threatening freshwater supplies and ecosystems, according to a new NASA and National Science Foundation-funded study of more than half of the world's freshwater supply.

Using more than 25 years of satellite temperature data and ground measurements of 235 lakes on six continents, this study — the largest of its kind — found lakes are warming an average of 0.61 degrees Fahrenheit (0.34 degrees Celsius) each decade. The scientists say this is greater than the warming rate of either the ocean or the atmosphere, and it can have profound effects.

The research, published in Geophysical Research Letters, was announced Wednesday at the American Geophysical Union meeting in San Francisco.

The rest of the story:
https://climate.nasa.gov/news/2378/study-climate-change-rapidly-warming-worlds-lakes/

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Nature Communications Published 19 April 2021
Phenological shifts in lake stratification under climate change
R. Iestyn Woolway <https://www.nature.com/articles/s41467-021-22657-4#auth-R__Iestyn-Woolway>, Sapna Sharma <https://www.nature.com/articles/s41467-021-22657-4#auth-Sapna-Sharma>, […] <>Eleanor Jennings <https://www.nature.com/articles/s41467-021-22657-4#auth-Eleanor-Jennings> 

OPEN ACCESS pdf
https://www.nature.com/articles/s41467-021-22657-4.pdf
Abstract
One of the most important physical characteristics driving lifecycle events in lakes is stratification. Already subtle variations in the timing of stratification onset and break-up (phenology) are known to have major ecological effects, mainly by determining the availability of light, nutrients, carbon and oxygen to organisms. Despite its ecological importance, historic and future global changes in stratification phenology are unknown. Here, we used a lake-climate model ensemble and long-term observational data, to investigate changes in lake stratification phenology across the Northern Hemisphere from 1901 to 2099. Under the high-greenhouse-gas-emission scenario, stratification will begin 22.0 ± 7.0 days earlier and end 11.3 ± 4.7 days later by the end of this century. It is very likely that this 33.3 ± 11.7 day prolongation in stratification will accelerate lake deoxygenation with subsequent effects on nutrient mineralization and phosphorus release from lake sediments. Further misalignment of lifecycle events, with possible irreversible changes for lake ecosystems, is also likely.

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Nature Published: 02 June 2021 <https://www.nature.com/articles/s41586-021-03550-y#article-info>
Widespread deoxygenation of temperate lakes
https://www.nature.com/articles/s41586-021-03550-y
Stephen F. Jane <https://www.nature.com/articles/s41586-021-03550-y#auth-Stephen_F_-Jane>, Gretchen J. A. Hansen <https://www.nature.com/articles/s41586-021-03550-y#auth-Gretchen_J__A_-Hansen>, […]Kevin C. Rose <https://www.nature.com/articles/s41586-021-03550-y#auth-Kevin_C_-Rose> 

Abstract
The concentration of dissolved oxygen in aquatic systems helps to regulate biodiversity1 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR1>,2 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR2>, nutrient biogeochemistry3 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR3>, greenhouse gas emissions4 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR4>, and the quality of drinking water5 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR5>. The long-term declines in dissolved oxygen concentrations in coastal and ocean waters have been linked to climate warming and human activity6 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR6>,7 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR7>, but little is known about the changes in dissolved oxygen concentrations in lakes. Although the solubility of dissolved oxygen decreases with increasing water temperatures, long-term lake trajectories are difficult to predict. Oxygen losses in warming lakes may be amplified by enhanced decomposition and stronger thermal stratification8 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR8>,9 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR9> or oxygen may increase as a result of enhanced primary production10 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR10>. Here we analyse a combined total of 45,148 dissolved oxygen and temperature profiles and calculate trends for 393 temperate lakes that span 1941 to 2017. We find that a decline in dissolved oxygen is widespread in surface and deep-water habitats. The decline in surface waters is primarily associated with reduced solubility under warmer water temperatures, although dissolved oxygen in surface waters increased in a subset of highly productive warming lakes, probably owing to increasing production of phytoplankton. By contrast, the decline in deep waters is associated with stronger thermal stratification and loss of water clarity, but not with changes in gas solubility. Our results suggest that climate change and declining water clarity have altered the physical and chemical environment of lakes. Declines in dissolved oxygen in freshwater are 2.75 to 9.3 times greater than observed in the world’s oceans6 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR6>,7 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR7> and could threaten essential lake ecosystem services2 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR2>,3 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR3>,5 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR5>,11 <https://www.nature.com/articles/s41586-021-03550-y#ref-CR11>.

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