Eutrophication

Eutrophication is a process by which water bodies become over-enriched with nutrients, notably nitrogen and phosphorus. These excess nutrients can come from a variety of sources, including agricultural runoff, sewage discharge, and atmospheric deposition from sources such as fossil fuel combustion. When these nutrients conjoin a water body, they can stimulate the growth of algae and other aquatic plants, leading to a condition known as an algal bloom.

The most common type of algae associated with eutrophication is cyanobacteria, also known as blue-green algae. Cyanobacteria are a type of photosynthetic bacteria that can thrive in nutrient-rich waters, particularly those that are high in nitrogen and phosphorus. When conditions are favorable, cyanobacteria can propagate rapidly, forming large blooms that can be damaging to both aquatic ecosystems and human health. In fact, a study uncovered that the increment in the water temperature due to climate changes up to the optimal temperature of 25°C can proliferate the reproduction of such bacteria. Likewise, climate change is projected to raise the global temperature by at least 1-4 degrees by the year 2100, which at that point practically makes the majority of stratified bodies of water algae-filled water that is both inedible and dilapidated to most aquatic species.

Climate change can contribute to eutrophication in several ways. Increased rainfall and flooding driven by climate change can direct more nutrient-rich runoff entering water bodies, which can cause an increase in algal blooms and other adverse effects on water quality. Warmer temperatures induced by climate change can exacerbate eutrophication as algae and other aquatic plants grow more rapidly in warm water. Warmer water can also cause oxygen levels to subside, creating favorable conditions for the growth of destructive algal blooms and other aquatic microorganisms.

Overall, eutrophication is a complex issue influenced by various factors, including climate change. Therefore, addressing eutrophication and its impacts will require a coordinated effort, including reducing nutrient inputs, managing land use practices, and addressing the root causes of climate change. You can find more about this in our countermeasure section oriented on the website. Nevertheless, it is crucial to address the eutrophication problem as it can significantly impact water quality, aquatic ecosystems, and human health.

Changing Precipitation Patterns

Climate change can influence precipitation patterns through various mechanisms. One of the most noteworthy is the increase in global temperatures due to the buildup of greenhouse gases in the atmosphere, primarily carbon dioxide. The warmer atmosphere can hold more moisture, leading to an increase in the vehemence and frequency of precipitation events. Greenhouse gases, such as carbon dioxide, methane, and water vapor, absorb some of the infrared radiation and re-radiate it back to the Earth's surface, effectively entrapping the heat in the atmosphere. This is understood as the greenhouse effect.

In addition to the direct influence of warming temperatures, climate change can also affect atmospheric circulation patterns. Transitions in sea surface temperatures and the melting of sea ice can alter the large-scale circulation of the atmosphere and ocean, leading to changes in precipitation patterns. For example, changes in the position and strength of the jet stream can alter the dispersal of precipitation over large areas.

Observations and modeling studies have delivered evidence of changes in precipitation patterns consistent with the effects of climate change. For example, a 2019 study found that the frequency of extreme precipitation events has risen in many parts of the world, particularly in high-latitude regions.

The datagram above from the research illustrates that TNn, in this case, referring to the trend of the daily minimum temperature of the warmest night of the year, indicates a rising trend, which exemplifies the shift in global temperature. This trend shows that globally, the minimum temperature of the warmest night of the year has been inflating over the past several decades, which is indicative of a broader trend of rising temperatures associated with climate change. While changes in TNn temperatures do not directly foretell changes in precipitation or weather patterns, they are an important indicator of the overall warming of the Earth's climate system, which is divined to have wide-ranging impacts on the meteorological conditions. Similarly, a 2018 study found that global warming is contributing to the increase in rainfall associated with hurricanes and typhoons.

It's important to note that while individual weather events cannot be directly attributed to climate change, the increasing frequency and severity of extreme precipitation events are consistent with the long-term trends expected from a warming climate.

Overall, the evidence suggests that climate change is impacting precipitation patterns through multiple courses, and the scientific community is in broad agreement that continued warming of the planet is likely to lead to further modifications in precipitation patterns with consequential implications for water resources, agriculture, and human societies.

Changes in Water Availability

Climate change has profound implications for water availability, as it can alter the delicate balance of the global water cycle. One way that climate change can affect water availability is by altering precipitation patterns mentioned earlier. As temperatures increase, the amount and intensity of precipitation events are likely to change. Such increment is introduced as the warmer air interacts with moisture in the atmosphere. Warmer air can retain more moisture than cooler air, which means that as temperatures increase, the atmosphere can harbor more water vapor. This can lead to more intense rainfall events when precipitation does transpire because there is more moisture available to be discharged in the form of rain. However, warmer air can also lead to changes in atmospheric circulation patterns, which can affect the distribution of precipitation.

For example, in some regions, warmer temperatures may cause atmospheric circulation patterns to shift, leading to changes in the location and frequency of precipitation events. In other regions, warmer temperatures may lead to raised evaporation rates from the land and water surfaces, which can diminish the amount of moisture available for precipitation, possibly leading to a prolonged drought. This could lead to more frequent and severe floods in some regions, while other regions may experience longer and more severe droughts. For example, research has shown that the Mediterranean region is projected to experience decreased precipitation in the future, which could lead to harder water accessibility to the local population.

Another way that climate change can affect water availability is by changing the timing and amount of snow and glacier melt. Snow and ice melt can be an important source of water for many regions, particularly in mountainous areas. However, as temperatures rise, snow and ice melt can occur earlier in the year, leading to receded water availability later in the summer months. Shrinking glaciers can also reduce the amount of water available for human use. For example, research has exhibited that the Himalayan glaciers are rapidly melting, which could have significant impacts on water availability for millions of people in the region. In fact, Himalayan glaciers have been forfeiting more than 8 billion tons of ice annually since the year 2000, according to a 2019 study that was released in the journal Science Advances. This is a two-fold increase in melting from 1975 to 2000.

The above graph represents the cumulative mass balance of major sites of glaciers found worldwide. As you can see, it is on a decline in the span of sixty years.

Nevertheless, the study also discovered that by the end of the century, the Himalayan glaciers had possibly lost more than one-third of their overall ice mass. The study also denoted that if such a rate were to continue, millions of people who rely on these glaciers as a source of water for drinking, irrigation, and hydropower generation would be substantially affected.

Additionally, climate change can affect water availability by increasing evaporation rates from surface water bodies. Warmer temperatures can cause increased evaporation rates, which can reduce the amount of water available for human use. This can be particularly problematic in regions that rely on surface water sources for irrigation or drinking water. For example, research has shown that the Aral Sea in Central Asia has significantly decreased in size due to increased evaporation rates caused by rising temperatures.

In conclusion, climate change can have significant impacts on water availability, and these impacts are likely to be felt differently in different regions. The complex interactions between climate, water, and human systems make it challenging to predict the exact nature and magnitude of these impacts, but scientific research has shown that they are likely to be significant. Understanding these impacts is crucial for developing effective strategies to adapt to and mitigate the effects of climate change on water availability.

References

De Raus Maure, E., Terauchi, G., Ishizaka, J., Clinton, N., & DeWitt, M. R. (2021). Globally consistent assessment of coastal eutrophication. Nature Communications, 12(1), 6142. https://doi.org/10.1038/s41467-021-26391-9

European Commission. (n.d.). Marine and coastal environment. https://environment.ec.europa.eu/. https://environment.ec.europa.eu/topics/marine-and-coastal-environment_en

Lucarelli, E. (n.d.). European Sustainable Phosphorus Platform - Eutrophication significantly increases greenhouse emissions. https://phosphorusplatform.eu/. https://phosphorusplatform.eu/scope-in-print/news/2075-eutrophication-significantly-increases-greenhouse-emissions

National Oceanic and Atmospheric Administration [NOAA]. (2023, January 30). What is eutrophication? https://oceanservice.noaa.gov/. https://oceanservice.noaa.gov/facts/eutrophication.html

O’Neil, J. M., Davis, T. W., Burford, M. A., & Gobler, C. J. (2011). The Rise of Harmful Cyanobacteria Blooms: The Potential Roles of Eutrophication and Climate Change. Harmful Algae, 14, 313–334. https://doi.org/10.1016/j.hal.2011.10.027