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What is climate change? Climate change refers to enduring alterations in temperature and meteorological patterns. These shifts may arise from natural causes, such as variations in solar activity or significant volcanic eruptions. Since the 19th century, anthropogenic activities have been the principal catalyst for climate change, primarily attributable to the combustion of non-renewable resources such as coal, oil, and natural gas. The combustion of fossil fuels results in greenhouse gas emissions, which function as a thermal insulator, enveloping the Earth, confining the sun's warmth, and elevating temperatures. The primary greenhouse gases responsible for climate change are carbon dioxide and methane (UN, 2021).

The mean temperature of the Earth's surface has increased by approximately 1.1°C compared to the late 1800s, which was before the industrial revolution. This temperature rise surpasses any recorded temperature in the past 100,000 years. The decade from 2011 to 2020 has been documented as the warmest on record. Furthermore, the preceding four decades have exhibited higher temperatures than any other decade since 1850 (UN, 2021). It is a common misconception that climate change primarily entails increased temperatures. However, the temperature increase is merely the matter's initial aspect. As the Earth functions as a complex system, any alterations in one domain can impact changes in all other domains.

The current ramifications of climate change encompass a range of issues, such as heightened periods of drought, limited access to water resources, extensive wildfires, elevated sea levels, flooding, the melting of the polar ice caps, destructive storms, and a reduction in biodiversity. Research on the correlation between climate change and water resources has primarily centered on surface water. Conversely, there is limited knowledge regarding the potential effects of climate change on groundwater (Costa et al., 2021). This bias primarily stems from the visibility and accessibility of the subject, which allow for relatively straightforward observation, measurement, and investigation of its component characteristics and interactions. Groundwater is often overlooked, possibly due to its subterranean location (Nkhonjera & Dinka, 2017). 

As mentioned earlier, limited studies have been conducted on the correlation between climate change and groundwater. Groundwater is a crucial natural resource that sustains life on Earth. It constitutes nearly 96% of the Earth's freshwater and accounts for 33% of total water withdrawals globally. Groundwater plays a vital role in sustaining various ecosystems, facilitating agricultural activities, and meeting the water requirements of human populations. According to Nourani et al. (2023), climate change's effects could significantly impact groundwater's availability, quality, and durability. The lack of research on the correlation between groundwater and climate change was succinctly described in the IPCC's Fourth Assessment Report. The report stated that there needed to be more research on the effects of climate change on groundwater and the impact of climate change on the interconnection between surface waters and hydraulically connected aquifers (Amanambu et al., 2020).

Below are listed the multifaceted impacts of climate change on groundwater. It is imperative to implement adaptation and mitigation strategies to preserve this invaluable resource for future generations.

1.       Alterations in precipitation patterns

Climate change has been observed to cause disturbances in precipitation patterns, resulting in alterations in the intensity and distribution of rainfall. This modification has an impact on the process of groundwater recharge, which involves the infiltration of water into the soil to replenish underground aquifers. Areas currently undergoing a rise in precipitation levels may experience an amplification in recharge rates, which could result in excessive groundwater depletion and pollution due to runoff and swift infiltration. On the other hand, regions subjected to extended periods of drought encounter a decrease in recharge, leading to a depletion of groundwater levels and subsequent water scarcity.

2.       Sea-level rise and saltwater intrusion

The increase in global temperatures results in melting glaciers and ice caps, which subsequently contribute to rising sea levels. This phenomenon presents a substantial risk to the reserves of coastal groundwater. The phenomenon of saltwater intrusion occurs due to rising sea levels, leading to the infiltration of saline water into freshwater aquifers, thereby rendering them unfit for utilization. Coastal communities that depend heavily on groundwater are encountering elevated salinity levels, threatening their water supply and agricultural activities. To address saltwater intrusion, it is essential to implement mitigation measures such as constructing seawater barriers or adopting managed aquifer recharge.

3.       Changed temperature patterns

Climate change has also been observed to cause disturbances in temperature patterns, which in turn have a negative impact on groundwater quality. Additionally, these changes adversely affect ecosystems that rely on groundwater. Elevated temperatures expedite the evaporation process, increasing the concentration of dissolved solids in groundwater. This reduces the water quality, rendering it unsuitable for human consumption and agricultural irrigation. In addition, alterations in temperature can disturb the intricate equilibrium of subterranean-based aquatic ecosystems, leading to the depletion of habitats and a reduction in biodiversity.

4.       The rise in occurrences of severe weather conditions

The impact of climate change is evident in the increased frequency and severity of extreme weather phenomena, including but not limited to hurricanes, floods, and droughts. These occurrences carry substantial consequences for groundwater resources. Water inundation can lead to the introduction of pollutants, sewage, and other hazardous substances into the groundwater, compromising its safety for human use. Furthermore, high-intensity precipitation events result in swift surface water flow, constraining the process of water infiltration and diminishing recharge rates. On the other hand, extended periods of drought result in a reduction in groundwater availability, which in turn leads to heightened competition and disputes over scarce water resources.

5.       Feedback loops and compounding effects

Feedback loops and compounding effects intensify the impacts of climate change on groundwater. An example of the impact of reduced snowfall in mountainous regions is the decrease in groundwater recharge during spring melt, which ultimately reduces water availability downstream. The limited availability of resources impacts natural ecosystems and human endeavours such as agriculture and hydropower generation. In addition, climate change-induced deforestation and land-use alterations exacerbate soil erosion, leading to a decline in groundwater recharge and quality.

In conclusion, due to climate change, groundwater, one of nature's most essential resources, faces significant challenges. The potential outcomes encompass modified precipitation patterns, rising sea levels, temperature fluctuations, and severe weather occurrences. These factors collectively affect the accessibility, quality, and long-term viability of groundwater resources. Efforts to adapt to and mitigate the effects of climate change on groundwater necessitate integrated measures, such as enhanced water management practices, sustainable land-use policies, and infrastructure investments. The prioritization of protecting and preserving groundwater is imperative to safeguard the well-being of ecosystems, communities, and future generations. By implementing sustainable practices and addressing the issue of climate change, we can ensure the preservation of this invaluable resource and establish a more resilient future for all.

References

1. Amanambu, A.C., Obarein, O.A., Mossa, J., Li, L., Ayeni, S.S., Balogun, O., Oyebamiji, A., Ochege, F.U. (2020). Groundwater system and climate change: present status and future considerations. Journal of Hydrology, 589, 125163. https://doi.org/10.1016/j.jhydrol.2020.125163.

2. Costa, D., Zhang, H., Levison, J. (2021). Impacts of climate change on groundwater in the Great Lakes Basin: a review. Journal of Great Lakes Research, 47, 1613-1625. https://doi.org/10.1016/j.jglr.2021.10.011.

3. Nkhonjera, G.K., Dinka, M.O. (2017). Significant of direct and indirect impacts of climate change on groundwater resources in the Olifants River basin: a review. Global and Planetary Change, 158, 72-82. http://dx.doi.org/10.1016/j.gloplacha.2017.09.011.

4. Nourani, V., Tapeh, A.H.G., Khodkar, K., Huang, J.J. (2023). Assessing long-term climate change impact on spatiotemporal changes of groundwater level using autoregressive-based and ensemble machine learning models. Journal of Environmental Management, 336, 117653. https://doi.org/10.1016/j.jenvman.2023.117653.

5. United Nation (UN). 2021. https://www.un.org/en/climatechange/what-is-climate-change.