The Impact of Climate Change on Lake Color

Liqing Wan

Department of Biology, Franklin and Marshall College, 637 College Ave, Lancaster, PA 17603, U.S.A.

Keywords: Climate Change, Global Warming, Lake Color, Algal Boom.

Abstract: Climate change's impact on lake color is a complex and great phenomenon that significantly influences the

health and dynamics of water ecosystems. This review delves into the intricate relationship between climate

change and changes in lake color, uncovering the underlying mechanisms driving these transformations and

their broader implications. Factors associated with global warming, such as increasing temperatures,

precipitation patterns, and shifting weather dynamics, directly or indirectly affect variables like nutrient input,

algal bloom growth, and water clarity. Consequently, these factors ultimately shape the distinct colors

observed in lakes worldwide. From green algae blooms to turbidity caused by glacial meltwater runoff,

various elements contribute to alterations in lake coloration while reflecting the role played by environmental

succession processes. This review paper comprehensively explains the complex interaction between climate

change and lake color from climatology's perspective as well as hydrology's and ecology's perspectives.

Furthermore, it emphasizes proactive measures aimed at mitigating adverse effects on freshwater ecosystems.

1 INTRODUCTION

Lake color, often taken for granted as simply a

picturesque aspect of nature, holds far greater

significance in the context of the changing climate.

Lakes are important indicators of the health and

dynamics of aquatic ecosystems, reflecting a delicate

balance of environmental factors. However, with the

looming threat of global warming and climate change,

the hues of these water bodies are undergoing

profound transformations, signaling potential

disruptions to their ecological equilibrium. This shift

in lake color is not merely an aesthetic alteration but

rather a harbinger of underlying environmental

upheavals that demand attention and action.

Climate change exacerbates global warming

primarily through the emission of greenhouse gases

from human activities. The Earth warms due to the

greenhouse effect caused by these gases retaining

heat in the atmosphere. The role of climate changes

in the lake's color change remains unknown, although

recent studies indicated that the climate, spatial

distribution, and land cover contribute to the lake's

color change. Elevated temperatures alter

precipitation patterns (Oleksy et al., 2022), leading to

fluctuations in nutrient and sediment inputs to lakes

(Gardner et al., 2021). This nutrient influx can fuel

algal blooms, altering the water's color to hues of

green or brown (Leech et al., 2018). Moreover, higher

temperatures accelerate chemical and biological

processes within lakes, potentially affecting the

composition of dissolved organic matter and the

proliferation of phytoplankton, both of which

influence lake color. Thus, while not directly

instigating color changes, global warming indirectly

influences lake color through its broader effects on

climate and environmental dynamics. The color of

summer lakes exhibits five distinct types of

seasonality, which can be attributed to well-

documented patterns of phytoplankton succession

(Topp et al., 2021). The lakes' characteristics and

surrounding environments are associated with the

frequency at which transitions occur between these

categories. Lakes situated in regions characterized by

significant interannual climate fluctuations and

variations in population density within their

catchments tend to display lower stability compared

to lakes with high inflow rates and minimal seasonal

surface area variation.

Algal blooms caused by global warming can

significantly impact the transparency and color of

lakes. Algae blooms often lead to turbidity in the

water because a large number of algae cells and the

organic matter produced by the algae are suspended

in the water, blocking the penetration of light. This

phenomenon can make the water less transparent.

Wan, L.

The Impact of Climate Change on Lake Color.

DOI: 10.5220/0013843700004914

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Conference on Renewable Energy and Ecosystem (ICREE 2024), pages 23-28

ISBN: 978-989-758-776-4

Global warming accelerates the growth of

phytoplankton and stimulates a general increase in

algal blooms. Most algal blooms observed in

freshwater lakes exhibit a green coloration,

effectively covering the water surface. Consequently,

lakes experiencing algal blooms often appear green

on their surfaces. Notably, between 2000 and 2010,

there was a significant rise in the occurrence of these

blooms worldwide, with a median bloom occurrence

value showing an increase of 44% (Hou et al., 2022).

Algae such as cyanobacteria also sometimes produce

toxins that cause the water to appear green, brown, or

red (Leech et al., 2018). This situation is made worse

because the toxins can be harmful to aquatic life and

human health.

Changes in temperature can impact the lake's

coloration, as rising temperatures increase dissolved

organic matter (DOM) concentrations in soil, and

increased precipitation leads to greater soil erosion

and runoff, transporting more nutrients like nitrogen

and phosphorus into the lake (Leech et al., 2018).

These nutrients are essential for algae and other

aquatic plant growth, leading to algal blooms and

overgrowth of aquatic plants that absorb more

sunlight and nutrients, causing the water to become

cloudy with varying colors. Additionally, human

agricultural activities contribute to eutrophication by

introducing large amounts of nutrients into lakes

through fertilizers, pesticides, animal manure runoff,

etc., resulting in changes in lake coloration.

Additionally, human agricultural activities can

contribute to lake eutrophication by introducing

significant nutrients into the water, changing the

lake's color. The presence of agriculture near lakes is

commonly associated with lake greening phenomena

(Leech et al., 2018). The application of fertilizers, the

use of pesticides, and the disposal of animal dung in

agricultural operations may lead to an increase in

nitrogen and phosphorus levels in aquatic habitats.

These nutrients stimulate the growth of

phytoplankton within the lake basin, leading to an

increase in algae biomass that covers the surface of

the water body. Lake eutrophication often manifests

as a "greening" effect caused by variations in algal

biomass and total phosphorus concentration (Leech et

al., 2018), which directly influence changes in lake

coloration due to alterations in water transparency

and the formation of a green or blue-green layer

composed of phytoplankton.

Understanding the intricate relationship between

climate change and lake color is imperative in

comprehending the broader repercussions of

environmental shifts on aquatic systems. The

motivation behind this research lies in the urgency to

decipher how rising temperatures, precipitation, and

altering weather patterns are influencing the optical

properties of lakes worldwide. By delving into this

phenomenon, we aim to shed light on the mechanisms

driving changes in watercolor and assess their

implications for water quality and ecological health.

To achieve this, the review adopts a comprehensive

research framework that integrates multidisciplinary

perspectives from climatology, hydrology, and

ecology. Through this interdisciplinary approach, we

endeavor to unravel the complexities of climate-

induced alterations in lake color and their cascading

effects on freshwater ecosystems.

2 FACTORS INFLUENCING

LAKE WATERCOLOR

Lake watercolor is influenced by various factors,

including climate, geology, and vegetation cover,

which interact across various scales to impact the

nature and amounts of terrestrial materials entering

the aquatic environment (Yang et al., 2022). Lakes

often exhibit distinct colors that differ from nearby

bodies of water, and while these colors are roughly

similar visually from lake to lake, there is

considerable variation. However, lakes with similar

dominant wavelengths in color profiles often share

comparable features.

2.1 Factors Influencing Blue Lake

Coloration and Regional Variations

Variations in precipitation and climate significantly

impact global glacier melt. Firstly, the rate at which

glaciers melt is accelerated by climate change,

primarily due to rising temperatures induced by

global warming. Global warming triggers the melting

of permafrost and glaciers, leading to a redistribution

of precipitation worldwide. The increasing

temperatures cause glaciers to melt more rapidly,

resulting in an initial acceleration of river flow.

However, if glaciers fail to reaccumulate, their

contribution to river flow may gradually diminish or

cease entirely as their size decreases over time,

causing a prolonged reduction in river flows.

Additionally, the increased melting of glaciers could

lead to the formation of glacial lakes (Zhang et al.,

2011). Moreover, snowfall plays a crucial role in

determining glacier mass balance and precipitation

patterns are vital for snow accumulation necessary for

glacier formation. When snow and ice accumulate

more than they melt or evaporate in alpine regions

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over time, it promotes gradual glacier formation; thus,

an increase in precipitation fosters glacier

development. Conversely, precipitation influences

the rate at which glaciers melt insufficient

precipitation can expedite melting while excessive

amounts can augment glacier bulk and decelerate the

melting process. Furthermore, surface reflectivity

modulation caused by precipitation affects glacier

melt (McGee, 2020). Thin layers of snow or ice

formed on glaciers reflect sunlight and impede

melting rates. Glacial retreats are intensified by

reduced snowfall and increased rainfall that

collectively contribute to loss of glacial mass. Rising

temperatures combined with changing patterns of

precipitation result in extensive glacier retreats that

heighten sea level rise risks while jeopardizing

coastal ecosystems and livelihoods.

Blue lake coloration is largely determined by

climatic and geomorphometric factors, which

suggests that blue lakes typically coincide with

regions of higher precipitation and cooler summer

temperatures or are deeper lakes situated at higher

elevations (Yang et al., 2022). Cooler summer

temperatures below 19°C are associated with a higher

prevalence of blue lakes, indicating a reduced

likelihood of algal growth and clearer water.

Moreover, the presence of winter ice cover is

associated with lower summer temperatures, thereby

increasing the likelihood of lakes in these regions

being characterized by a blue hue approximately

twice as much. The depth of a lake plays a crucial role

in the functioning of its ecosystem. Ice-covered lakes

are experiencing a more rapid increase in temperature

compared to ambient air temperatures, with the

deepest ice-covered lakes exhibiting particularly

accelerated warming rates (O’Reilly et al., 2015).

Furthermore, deeper lakes consistently exhibit a

higher likelihood of appearing blue when compared

to shallower lakes. Projections indicate that the

ongoing warming trend and potential loss of winter

ice cover may result in fewer blue lakes, especially in

regions characterized by higher levels of precipitation.

Typically, blue lakes are located in high-elevation,

steep watersheds with little vegetation and colder

yearly averages. These factors lead to a limited supply

of terrestrial nutrients in the lake, which reduces

productivity and decreases water clarity. Lake

morphology and basin area heterogeneity can also

influence lake coloration. For instance, even in cold

regions (with an average annual temperature below

4.5°C), green/brown lakes may occur if they are

shallow (with an average depth less than 2.5 m) and

have a large drainage area (greater than 12.5

)(Oleksy et al., 2022). This is because small,

shallow lakes generally exhibit higher productivity

levels than deep lakes.

A study showed a similar pattern of blue lake

color, in which increased temperature and

precipitation are the important factors of bluer lake

color (Cao et al., 2023). However, the study indicated

that warming and wetter climates are the key

characteristics linked with deep and clear lakes

becoming bluer (Cao et al., 2023), in contrast to Yang

et al.'s finding that the bluer lake was usually found

in wetter and colder settings. The dominant

wavelength of a lake in the same region can vary

significantly; a yellow or brown lake may be adjacent

to a blue lake. These regional variations imply that

other non-spatial factors might also contribute to lake

color changes (Yang et al., 2022).

The differences in the study results could be

explained by the multifactors that contributed to the

change in the color of lake water. The lakes in eastern

China, which are mostly cultivated and urban, are

shallow, cloudy, and eutrophic, and their color is

mainly green and yellow (Cao et al., 2023). The cold,

high-altitude regions of northern China are affected

by climate change, as melted glacial water flows into

lakes and increases their size. At the same time, the

increase in precipitation caused by climate change not

only increases the flow rate of water but also

increases the clarity and decreases the greening rate

of lakes at cold and high altitudes due to the lack of

vegetation cover in the watershed (Cao et al., 2023).

2.2 Seasonal Variation in Lake Color

Regional drivers caused the long-term seasonal

change in lake color. In recent decades, lakes in the

United States' western Pacific area have tended to

decrease the dominant wavelength and become bluer

in color (Topp et al., 2021 & Cao et al., 2023). A

study that focused more on seasonal variations

investigated the periodic seasonality of the lake color

changes. Four separate phenological groups were

identified based on the summer color phenological

characteristics of over 26,000 lakes in the United

States between 1984 and 2020 (Topp et al., 2021).

The median dominant wavelength of spring greening

lakes is significantly lower than that of other lake

types. Spring greening appears green at the beginning

of summer and gradually shifts towards the blue end

of the spectrum during summer and fall. From May to

August, the Summer greening lake turns green before

returning to a blue hue in winter. Bimodal lakes have

color distribution between blue and green on the

spectrum, experiencing two distinct phases of color

change yearly. Aseasonal lakes show no significant

The Impact of Climate Change on Lake Color

seasonal color patterns with their color distribution

remaining in the green part of the spectrum (Topp et

al., 2021).

2.3 Impact of Agricultural Activities

and Lake Turbidity on Lake Color

This section discusses the influence of agricultural

activities on lake turbidity and coloration, drawing

parallels between the United States and eastern China.

It highlights the role of land cover and land use

patterns in altering lake ecosystems, with agriculture

often associated with lake greening and wetlands

linked to lake turbidity. Additionally, it examines the

impact of agricultural runoff, particularly nitrogen

and phosphorus fertilizers, in stimulating

phytoplankton growth and contributing to lake color

changes. Furthermore, the section explores

meteorological factors, such as temperature and wind

speed, and their influence on cyanobacteria blooms in

Chinese lakes, emphasizing the intricate interplay

between environmental variables and lake dynamics.

The United States exhibits a higher proportion of

agricultural activities in its green and turbid lake

watershed (Leech et al., 2018), mirroring the similar

pattern observed in eastern China, where these

watersheds are predominantly found around areas of

agriculture or urbanization (Leech et al., 2018 & Cao

et al., 2023). Despite geographical differences, the

shared cultural environment contributes to the

turbidity of lakes, resulting in their predominant

green or brown appearance. The number of blue lakes

in the continental United States fell between 2007 and

2012. while the number of turbid lakes increased.

This change may be attributed to alterations in land

cover and land use patterns surrounding the lakes.

The widespread presence of agriculture in lake

watersheds is typically associated with lake greening,

while the prevalent existence of wetlands is often

linked to lake turbidity. The increasing discharge of

fertilizers, including phosphorus and nitrogen from

farms, may act as a catalyst for the growth of

phytoplankton, especially the blue-green algae that

blanket the surface of lakes (Leech et al., 2018). The

absence of dissolved oxygen in wetlands significantly

hinders the breakdown of organic materials. As a

result, adjacent lakes often receive higher organic

matter inputs from wetlands, making the water a rich

brown color.

Furthermore, it is believed that wind speed and

temperature have a significant meteorological impact

on cyanobacteria blooms in Chinese lakes. The study

revealed that approximately 80% of cyanobacteria

blooms occur in areas with calm waters, where wind

speeds are below 3 m/s and temperatures exceed 16°C

(Wang et al., 2023). Temperature exerts an impact on

the enzymes within algae cells, facilitating their

growth. Conversely, when wind speeds surpass 3 m/s,

strong winds effectively hinder the accumulation of

algae on the water's surface.

2.4 Effects of Turbidity on Planktonic

Organisms and Radiation

Absorption

Compared to blue and brown lakes, the biomass ratio

of zooplankton to phytoplankton is smaller in green

and turbid lakes (Leech et al., 2018). The increase in

the turbid lake's color did not inhibit plankton growth.

Although light attenuation is reduced due to increased

turbidity (Olson et al., 2018). However, the mixing

layer becomes lighter as the color increases, allowing

the phytoplankton's photosynthetic cells to be still

exposed to light in surface water. In green and turbid

lakes, there is an average of 60% blue-green algae,

which is a type of phytoplankton that forms matting

on the lake's surface (Leech et al., 2018). Decreased

zooplankton to phytoplankton biomass ratios may

result from the presence of blue-green algae and

elevated microcystin toxin concentrations in green

and turbid lakes, thereby impeding zooplankton's

access to food resources and reducing their ability to

consume phytoplankton. However, blue and brown

lakes have more algae that zooplankton can feed on.

Zooplankton in these lakes may have more algae

available for consumption, increasing their ability to

consume phytoplankton, resulting in a higher

biomass ratio of zooplankton to phytoplankton.

The consequence of glacier melting induced by

global warming often results in turbid meltwater.

Murky lakes, which are nourished by glaciers, can be

found worldwide and significantly impact planktonic

life. Glacial flour, referring to mineral-suspended

particles, is consistently present in glacier-fed lakes.

Glacial flour is formed when ice scrapes across

bedrock, resulting in a fine powder composed of silt

and clay-sized particles. Planktonic organisms are

adversely affected by glacial flour due to its various

characteristics. The abundance of glacial flour in the

lake hinders planktonic species that rely on filter-

digesting systems from obtaining food effectively.

This hindrance arises from the lake ecosystem's

overlapping sizes between organic and glacial

particles. Furthermore, planktonic life may also

consume a substantial concentration of glacial flour

alongside organic particles as their source of nutrition.

Consequently, significant levels of glacial flour can

be found within the digestive tracts of planktonic

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animals, altering their ability to absorb organic matter

while reducing their energy requirements for growth

and reproduction (Sommaruga, 2015).

Turbidity has a major effect on radiation

absorption and transmission, especially when it

comes to light radiation. Over the visible spectrum

and at UV wavelengths, it reduces light intensity.

Moreover, turbidity influences the ability of attached

algae to defend themselves against high levels of

radiation. Turbidity, for example, can protect attached

algae against the negative effects of light radiation,

particularly UV radiation, by blocking light

penetration. This occurrence reduces their exposure

to light radiation and potentially mitigates damage to

their photosystem. In lakes fed by glaciers where

turbidity levels correlate with increased rates of light

attenuation, this protective effect becomes notably

apparent (Olson et al., 2018). Attached algae exhibit

enhanced resistance to elevated levels of radiation in

situations characterized by concentrated turbidity

through regulating the absorption and dissipation of

light. Consequently, in areas with high levels of

radiation, turbidity serves as a transient defense

mechanism for adherent algae (Nicolás and Balseiro,

2014).

3 CONCLUSION

The findings presented in this paper emphasize the

significance of comprehending the correlation

between climate change and lake color to elucidate

broader patterns in freshwater ecosystems. In

conclusion, climate change has a multifaceted impact

on lake color due to the complex interplay of

environmental factors. The rising temperatures and

changing precipitation patterns driven by global

warming have resulted in altered nutrient and

sediment inputs to lakes, promoting algae blooms and

modifying watercolor. Furthermore, human

agricultural activities contribute significantly to the

eutrophication phenomenon by introducing a

substantial amount of nutrients into the lake, which

further affects its coloration. Regional variations in

lake color reflect the influence of diverse climatic,

geological, and anthropogenic factors. Typically,

blue lakes are associated with lower temperatures and

nutrient levels; whereas green and turbid lakes

primarily result from farmland runoff and wetland

discharge. A comprehensive understanding of these

intricate relationships between climate change and

lake color is crucial for comprehending the broader

impacts on freshwater ecosystems as well as guiding

effective management strategies amidst ongoing

environmental changes.

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