Effects of Global Climate Change on the Acidification of the Ocean and Coastal Upwelling

Introduction

Warming, de-oxygenation, and acidification are causing changes in the world ocean and have the consequences on marine life as well as ocean-based economies (Boch et al. 1125). Global warming and climate change have been on the rise in recent years due to increasing carbon dioxide (CO2) emission from human activities alongside the burning of fossil fuels(Turley & Boot, p.1). The increasing level of CO2 in the atmosphere alters the surface oceans chemistry and increases their acidity. Ocean acidification and coastal upwelling have direct impacts on the marine system as well as the human environment. The following paper will detail the effects of global climate change on ocean acidification and coastal upwelling.

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CO2 concentration has been on the rise due to human activities like land-use change. Lenton et al. (31) highlighted that the ocean is a key player in limiting the rate of climate change as it absorbs around 30% of the annual global emissions. The absorption of the emission by the ocean alters its chemistry and thus impacts the marine ecosystem such as species composition. Ocean acidification is therefore directly induced by atmospheric emissions of CO2 (Turley & Boot, p.1).

Ocean acidification is of significant interest in areas with seasonal upwelling such as the California coast (Bakun et al., 87). Due to strong winds on the coast, the shoreline surface water is moved away from the shoreline and is replaced by colder deep water from below which is rich in nutrients. The cold water has more CO2 content and thus a lower pH and Coastal upwelling, therefore, supports marine life as it provides nutrient-rich water. Global climate change is a threat to marine life. This is because an increase in the CO2 content is expected to increase ocean acidity in these coastal upwelling regions and therefore affect the marine ecosystem (Bakun et al., 87).

Importance of the Study

The study of multiple environmental drivers and their interactive effects advances human understanding of the changing ocean conditions and its real-world consequences. According to (Boch et al. 1125). Scientists and policymakers are concerned that ocean acidification has potential implications on the marine ecosystems. As such, it is crucial to study and understand how global warming affects ocean acidification and coastal upwelling. Future ocean acidification is associated with ocean warming, among other environmental consequences (Boch et al. 1125). It is therefore vital to study and understand global climate change, and its effects as viable emission strategies can be developed to facilitate sustainable adaptation.

Impacts and Effects

An increase in the atmospheric CO2 increases the acidity of the ocean water, which consequently increases the acidity of the ocean water. An increase in ocean acidity lowers the pH value of the seawater. Many organisms in the water depend on carbonate balance, which has been affected by the onset of human activities such as industrialization. Due to ocean acidification, the pH has decreased by 30%, and there has been a 16% decrease in carbonate ion concentration (Lachkar, 90). Organisms use carbonate to make reef and shell systems and a reduction in carbonate level is a threat to these organisms. Most of these organisms are a direct source of food for human and therefore, in the future, the food security will be under threat. The marine ecosystem may also not be sustainable in the long run.

Consequences

A decrease in ocean pH has the implications that there could be loss of skeleton or shell-forming organisms in the marine ecosystem (Turley & Boot, 2). In the future, ocean acidification could affect the health, abundance, physiology, behavior, and biochemical characteristics of the marine organisms. This could also affect future food security for humans who directly feed on aquatic organisms or affects the ecosystem that supports humans. Ocean acidification impacts marine organisms due to changes in pH, increasing the partial pressure of CO2, and reduced calcium carbonate saturation level (Lachkar, 93). Deviation in the carbonate levels creates a corrosive environment for organisms such as the calcifying ones.

Past Data

A station at Hawaii observed the ocean over the last 20 years and reported an increase of CO2 in the ocean water as well as a decrease in the pH value which indicated a rise in atmospheric CO2(Turley & Boot, p.2). Before industrialization, the average ocean pH was 8.2 globally, which has today decreased by 0.1, equivalent to a 30% increase in ocean acidity (Turley & Boot, p.2). The figure below indicates the atmospheric CO2 changes recorded at a Hawaii station.

(Turley; C. M.; and Kevin Boot. "Environmental consequence of ocean acidification: a threat to food security." UNEP Emerging Issues Bulletin 2010: 01.)

Figure 2: Surface pH

(Part.B "Climate Change 2014 Impacts; Adaptation; and Vulnerability." 2014).

The above figure (fig.2) illustrates that the surface ocean pH has been on the decline since the industrial revolution started. From the above figure, it is evident that the ocean CO2 concentration has been on the increase, reflecting an increase in atmospheric CO2. There has been a decrease in the pH value as the acidity increases.

In supporting the fact that the CO2 levels have increased, the figure below (fig.3) illustrates historical oxygen changes in the ocean.

Figure 3: historical ocean oxygen content change

(Part; B. "Climate Change 2014 Impacts; Adaptation; and Vulnerability." 2014).

Current Data and Future Prediction

The estimation of the future ocean acidification can be based on different circumstances. With the current CO2 emissions, the next prediction is that the global pH will have a 0.3 units decrease by the end of 21 century which is equal to 150% increase in the acidity levels(Turley & Boot, 2).

Figure 4: future scenarios for climate change for the 21 century

(Part; B. "Climate Change 2014 Impacts; Adaptation; and Vulnerability." 2014).

From the above figure (fig.4), we depict that global warming is expected to be on the rise to the end of the century. As such, there will be more emission of CO2 and consequently increased ocean acidification.

Effect on Marine Ecosystems

Ocean acidification could affect the shellfish, which is ecologically and economically important. The California oysters, for example, are of significant commercial value and most importantly, the key organisms in the marine ecosystem (Garcia-Reyes et al., 2015). Ocean acidification would make such species susceptible to the adverse effects of the acidity, reducing the carbonate needed for early development in building hard structures and shells.

Ocean acidification could also affect the coral reefs, which depend on the carbonate in the water to form internal skeletons. Acidification reduces the pH, which decreases their ability to create and keep their hard composition (Garcia-Reyes et al., 2015). Further, ocean acidification also impacts on animal behavior. Animals such as clownfish stay close to their home base under normal pH levels. However, increasing acidity moves then away from their homes, which expose them to a higher risk to predators (Garcia-Reyes et al., 2015).

Effect on Humans

Human depend on the marine organisms for their food. Increasing the acidity of the ocean water destroys habitats for marine animals, which leads to reducing food levels and security for humans. Increasing the acidity discourages the development of organisms such as shellfish due to diminishing amounts of carbonate, which leads to a substantial decline of these organisms. As a source of income for many, the considerable loss in the amount of shellfish subsequently reduces the revenues incomes.

Example of a Geographical Region

An example of a geographical region is given for California. Lachkar (90) highlighted that California is one example of an upwelling area with highly productive marine ecosystems, and they naturally experience low calcium carbonate minerals. This is since the deep water that is depleted of the carbonate ion is upwelled to the surface alongside organic matter respiration believed to release CO2 and intake carbonate. The intensity of the ocean acidification is projected to increase in the future in areas such as California due to an increase in atmospheric CO2 levels (Lachkar, 90). The intensification of upwelling favorable winds has been suggested over the decade for Eastern Boundary Upwelling Systems (EBUS) California included. The strengthening of the upwelling has been attributed to global warming and is expected to increase in the future. Climate change has been credited for the increase in upwelling facilitating winds over natural variability (Lachkar, 90).

Works Cited

Bakun, Andrew, et al. "Anticipated effects of climate change on coastal upwelling ecosystems." Current Climate Change Reports 1.2 (2015): 85-93.

Boch, Charles A., et al. "Effects of current and future coastal upwelling conditions on the fertilization success of the red abalone (Haliotisrufescens)." ICES Journal of Marine Science 74.4 (2017): 1125-1134.

Garcia-Reyes, Marisol, et al. "Under pressure: Climate change, upwelling, and eastern boundary upwelling ecosystems." Frontiers in Marine Science 2 (2015): 109.

Lachkar, Zouhair. "Effects of upwelling increase on ocean acidification in the California and Canary Current systems." Geophysical Research Letters 41.1 (2014): 90-95.

Lenton, Andrew et al. "Effects Of Climate Change On Ocean Acidification Relevant To The Pacific Islands." Reliefweb.Int, 2018, https://reliefweb.int/sites/reliefweb.int/files/resources/3_Ocean_Acidification.pdf. Accessed 24 July 2019.

Part, B. "Climate Change 2014 Impacts, Adaptation, and Vulnerability." (2014).

Turley, C. M., and Kevin Boot. "Environmental consequence of ocean acidification: a threat to food security." UNEP Emerging Issues Bulletin (2010): 01.