The new study sheds light on the significant impact of excessive groundwater extraction on Earth's tilt and rotation. The relentless human demand for groundwater, which serves as a vital source of drinking water, livestock sustenance, and crop irrigation, has led to the depletion of subsurface reserves. Over a span of more than a decade, this persistent extraction has caused a noticeable shift in Earth's rotational axis, tilting it towards the east at a rate of approximately 1.7 inches (4.3 centimetres) per year.
The consequences of this axis shift extend beyond the observable changes in Earth's rotation. It also contributes to the rise in global sea levels, exacerbating the already critical issue of sea-level rise. The research, published in the journal Geophysical Research Letters, highlights the dominance of groundwater redistribution as the largest contributor to the drift of the rotational pole among climate-related causes.
Between the years 1993 and 2010, a significant amount of groundwater, exceeding 2,150 gigatons, was extracted by humans from beneath the Earth's surface. This extraction was primarily concentrated in western North America and northwestern India, as per estimates published in 2010. To provide some perspective, if this extracted groundwater were to be poured into the ocean, it would lead to a rise in global sea levels by approximately 0.24 inches (6 millimetres).
In 2016, a separate group of researchers discovered a correlation between the movement of Earth's rotational axis and changes in the mass of glaciers, ice sheets, and terrestrial liquid water reserves. Notably, any alteration in mass on Earth, including variations in atmospheric pressure, has the potential to influence its axis of rotation. In an interview to CNN, lead study author Ki-Weon Seo, a professor in the department of Earth science education at Seoul National University in South Korea, explained that axis shifts caused by atmospheric pressure changes are periodic in nature, meaning that the rotational pole oscillates and eventually returns to its previous position. Seo and his colleagues aimed to explore long-term changes to the axis, specifically focusing on how groundwater contributes to this phenomenon, which had not been previously accounted for in scientific investigations.
The study emphasises the need to address unsustainable groundwater practices and implement responsible water resource management. While groundwater pumping can provide a lifeline in regions facing water scarcity and drought due to climate change, it is essential to recognize the finite nature of subterranean water reserves and the slow rate at which they replenish. The findings underscore the unintended global consequences of excessive groundwater extraction, urging people to be aware of the impact their actions have on Earth's systems.
Furthermore, the research demonstrates the importance of incorporating groundwater data into computer models and utilising observations of Earth's rotation to understand past changes and trace the evolution of planetary systems over time. By leveraging this knowledge, scientists can better comprehend the long-term effects of climate warming on Earth's systems.
The research serves as a wake-up call, highlighting the critical need for sustainable groundwater management and increased awareness of the interconnectedness of human activities and the Earth's systems. It is crucial to strike a balance between meeting water demands and preserving the integrity of our planet's natural resources for the benefit of current and future generations.
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