Air Adalah Kehidupan, Seberapa Besarkah Cadangan Air Tanah Kita?

Summary

A groundbreaking study reveals the global volume of modern groundwater, crucial for energy, food security, and ecosystem health. Using tritium from nuclear tests as a tracer, researchers estimate 23 million cubic kilometers of groundwater in the upper crust, with only 0.1 to 5.0 million cubic kilometers being less than 50 years old and potentially renewable. However, this modern groundwater, equivalent to a 3-meter deep layer over continents, is a limited resource that must be managed wisely in the face of climate change and increasing demand.

Takeaways

• 🌍 Earth has a vast amount of underground water that could theoretically flood continents to a depth of 180 meters or raise global sea levels by 52 meters.
• 💧 The percentage of renewable water reserves on a human timescale is small and was previously unknown.
• 🔍 A study published in Nature Geoscience in 2015 by researchers from the University of Victoria in Canada shed light on the global volume and distribution of modern groundwater.
• 🕰️ The age of groundwater is significant for geological processes, including chemical weathering, ocean eutrophication, and climate change, with ages ranging from months to millions of years.
• 💣 The use of radioactive tritium, a by-product of thermonuclear weapon testing, has helped in dating groundwater to the last 50 years, indicating modern groundwater.
• 📊 Tom Glison and colleagues analyzed nearly 3800 groundwater samples to map the abundance of modern groundwater at various depths.
• 📈 The research concluded that the upper crust contains about 23 million cubic kilometers of groundwater, with less than 6% being modern and potentially renewable.
• 🌊 Modern groundwater, although a small fraction, is equivalent to a 3-meter deep layer spread across continents and is considered a potentially renewable resource.
• 🚨 The study emphasizes that modern groundwater should be viewed as a potentially renewable resource, but its replenishment is not guaranteed in the future.
• 🌱 Soils and groundwater play a crucial role in sustaining ecosystems and supporting human adaptation to climate variability and change.
• 🌡️ Climate change is expected to increase the demand for groundwater due to more frequent climate extremes, impacting water and food security.

Q & A

What is the potential impact of Earth's underground water on sea levels?

Earth's underground water is capable of raising sea levels around the planet by 52 meters.

What is the significance of renewable water reserves in managing water resources?

Renewable water reserves are important for governments to manage water resources in the face of increasing demand, especially for energy and food security, human and ecosystem health.

Why was the size of renewable water reserves unknown until recently?

The size of renewable water reserves was unknown because the global volume and distribution of groundwater that is less than 50 years old had not been studied until the research conducted by hydrogeologists.

What method did researchers use to estimate the age and volume of groundwater?

Researchers used radioactive tritium, a by-product of testing thermonuclear weapons, to estimate the age of groundwater and map its abundance at different depths.

What is the significance of the research published in Nature Geoscience in 2015?

The research published in Nature Geoscience in 2015 provided the first comprehensive study on the global volume and distribution of modern groundwater, which is crucial for understanding renewable water reserves.

What is the estimated total volume of groundwater in the upper crust of Earth?

The upper crust of Earth contains almost 23 million cubic kilometers of groundwater.

What percentage of the total groundwater is considered modern and potentially renewable?

Less than 6% of the total groundwater is modern, with only 1.5% being potentially renewable on a human timescale.

How much of the total groundwater volume is less than 50 years old?

Between 0.1 to 5.0 million cubic kilometers of groundwater are less than 50 years old.

Why is it important to know the location of modern groundwater?

Knowing the location of modern groundwater is important for sustainable water management and to adapt to climate variability and change.

What challenges does climate change pose to groundwater resources?

Climate change can lead to more frequent climate extremes, intense droughts, and flooding, which increase the variability in rainfall, soil moisture, and surface water, affecting the sustainability of groundwater resources.

How does the lack of groundwater observations limit our understanding of its role in climate systems?

The lack of groundwater observations limits our understanding of the dynamic relationship between groundwater and climate systems, making it difficult to assess the impact of climate on groundwater and vice versa.